Written by: Jagdish Reddy
Sources: University Extension Programs, Horticulture Research Publications
Last Updated: April 2026
Quick Answer
Companion planting works by using natural plant relationships to repel pests, attract beneficial insects, fix soil nitrogen, and improve overall crop yields. The most effective companion planting rules are based on plant chemistry, root behaviour, and growth habit — not folklore. Growers who apply these rules consistently see fewer pest problems, reduced fertiliser needs, and healthier harvests across all climate zones.
What Is Companion Planting?
Companion planting is the practice of growing two or more plant species in close proximity to achieve mutually beneficial results. These benefits can include pest deterrence through volatile chemical compounds, nitrogen fixation through legume root nodules, improved pollination by attracting beneficial insects, and physical benefits like shade, wind protection, or structural support.
It is one of the oldest forms of Integrated Pest Management (IPM) and is widely recommended by extension services, organic certification programmes, and the FAO for small-scale and commercial growers alike. Research-based guides such as this companion planting in home gardens guide further explain how plant partnerships improve garden productivity.
Why Companion Planting Rules Actually Matter
Understanding companion planting rules can be the difference between a garden that fights itself all season and one that manages its own pest pressure.
Many gardeners place plants wherever space allows — and then spend the whole season dealing with aphid explosions, unexplained leaf curl, and stunted growth.
The rules of companion planting give growers a clear framework before anything goes in the ground. In warm climates like tropical Southeast Asia or subtropical India, these rules manage pest pressure that builds fast under heat and humidity.
In cooler temperate regions across Europe and North America, the same principles help maximise a short growing season. These 15 rules are drawn from field observation, crop science, and grower experience across USDA hardiness zones (commonly used global climate reference) 3 through 11.
Quick Summary: What You Will Learn
- The science behind why certain plants help or harm each other
- Which vegetable combinations consistently produce better results
- Practical examples can also be seen in this companion plants guide
- Common companion planting mistakes beginners make
- How to apply these rules across different climate zones
- A companion planting chart covering 12 major vegetables
- How spacing, timing, and soil type affect companion planting outcomes
15 Companion Planting Rules Every Vegetable Gardener Should Know
Rule 1: Use the Three Sisters System for Maximum Space Efficiency
The Three Sisters — corn (Zea mays), beans (Phaseolus vulgaris), and squash (Cucurbita spp.) — represent one of the most documented companion systems in agricultural history.
Corn provides a trellis for climbing beans. Beans fix atmospheric nitrogen (N) into the soil through root nodules, feeding the high nitrogen demands of corn. Squash spreads along the ground, suppressing weeds and retaining moisture.
Multi-season garden trials show this trio works well in USDA hardiness zones (commonly used global climate reference) 4–10 and performs especially strongly in warm continental climates with long, dry summers.
Rule 2: Always Plant Basil Near Tomatoes
Basil (Ocimum basilicum) is one of the most widely used companions for tomatoes. Growers interested in cultivation methods can also refer to this basil growing guide. The volatile aromatic oils — particularly linalool and estragole — deter aphids, whitefly, and spider mites.
Many growers notice fewer thrips infestations when basil is interplanted at 30–45 cm (12–18 inch) spacing between tomato rows.
The benefit is strongest in warm climates above 20°C (68°F), where both plants thrive simultaneously. Pinch basil flowers regularly to maintain high essential oil concentration in the leaves.
Rule 3: Never Plant Fennel Near Most Vegetables
From field observation, fennel (Foeniculum vulgare) is one of the most allelopathic vegetables in the garden. Its roots and decomposing foliage release compounds that inhibit the growth of tomatoes, beans, peppers, and lettuce.
Very common problem — beginners often plant fennel in the main vegetable bed without knowing this. Grow it in an isolated bed or container at least 1 metre (3 feet) away from other crops.
The one exception: fennel attracts beneficial predatory wasps. Positioning it near the garden perimeter captures that benefit without allelopathic damage to neighbouring crops.
Rule 4: Use Marigolds as a Living Pest Barrier
French marigolds (Tagetes patula) produce thiophenes from their roots — sulphur-containing compounds toxic to soil nematodes (Meloidogyne spp.). Continuous marigold planting suppresses root-knot nematode populations over one or more growing seasons.
In tropical and subtropical regions where nematode pressure is high, border-planting marigolds around tomato, pepper, and bean beds produces measurable results.
Happens in hot weather: marigolds also deter whitefly and aphids through their foliar scent throughout summer. Easy to grow, low maintenance, and effective across most climate zones.
Rule 5: Let Legumes Build Nitrogen for Heavy Feeders
Beans and peas fix atmospheric nitrogen through symbiotic Rhizobium bacteria in root nodules. Grower trials suggest planting beans alongside brassicas, corn, or leafy greens significantly reduces the need for supplemental nitrogen fertiliser.
For organic systems, this is one of the most important companion planting rules. After harvest, cut legume stems at soil level rather than pulling roots.
The root nodules continue releasing fixed nitrogen as they decompose — providing a slow-release N boost of up to 100–200 kg N/ha depending on the variety and season length.
Rule 6: Keep Alliums Away From Beans and Peas
Onions, garlic, leeks, and chives (Allium spp.) release sulphur-based compounds that interfere with the nitrogen-fixing Rhizobium bacteria in legume root nodules.
Common beginner mistake: planting garlic borders around bean beds thinking it will protect against aphids, without realising nitrogen fixation is being disrupted.
Keep all alliums at least 50 cm (20 inches) away from any legume crop. Alliums are excellent companions for brassicas, tomatoes, and roses — just not legumes.
Rule 7: Interplant Shallow and Deep Rooters
Matching plants by root depth is one of the most practical but underused companion planting rules. Shallow-rooted vegetables like lettuce, spinach, and radish can be interplanted with deep-rooted crops like carrots, parsnips, and tomatoes without significant competition.
In raised bed gardening — especially common in urban settings — this allows two harvests from the same bed simultaneously.
Drip irrigation benefits this combination particularly well, as each root zone can be targeted independently without overwatering the shallow layer.
Rule 8: Use Nasturtiums as Trap Crops
Nasturtiums (Tropaeolum majus) are among the most effective trap crops for the home garden. Aphids — particularly black bean aphid and peach-potato aphid — strongly prefer nasturtiums over most nearby vegetable crops.
Many growers notice aphid populations cluster almost entirely on nasturtiums when planted at garden edges or between rows. Allow them to gather, then cut and remove the infested plants.
Or introduce beneficial predators like ladybirds and lacewings directly onto the nasturtium colonies. In cooler climates, nasturtiums self-seed reliably and return each year with minimal effort.
Rule 9: Dill and Carrots Need Careful Timing
Young dill (Anethum graveolens) benefits carrots by attracting predatory wasps and hoverflies that prey on carrot fly larvae. However, mature dill produces allelopathic compounds that inhibit carrot root development if both plants flower at the same time.
From field observation: plant dill as a seedling near young carrot rows, then harvest it before it bolts. This timing detail is easy to miss for beginners who sow both from seed together.
Dill also cross-pollinates with carrots and fennel, affecting seed purity. Keep dill well away from fennel to avoid hybridisation if saving seed.
Rule 10: Grow Brassicas With Aromatic Herbs to Confuse Pests
Cabbage white butterfly (Pieris rapae) locates brassica crops primarily through volatile host-plant scent. Interplanting brassicas with dill, thyme, sage, or mint disrupts this process, reducing eggs laid directly on leaves.
This is a well-documented IPM strategy recommended by extension services in the UK, Australia, and North America.
In warm climates where brassica pest pressure is continuous, aromatic herb borders need refreshing every 4–6 weeks as essential oil concentration drops in high heat. Nothing unusual — in temperate zones, a single thyme border often protects the full brassica season.
Rule 11: Respect Nightshade Family Boundaries
Tomatoes, peppers, aubergines, and potatoes all belong to the Solanaceae family. Grouping them together significantly increases shared disease risk — especially late blight (Phytophthora infestans), tobacco mosaic virus, and fusarium wilt.
Many growers place potatoes next to tomatoes assuming similar water and fertility needs. In practice, any disease outbreak spreads between Solanaceae plants very rapidly.
Maintain a minimum 1–1.5 metre (3–5 feet) separation. In small gardens, use crop rotation — never follow one Solanaceae crop with another in the same bed for at least two seasons.
Rule 12: Chives Improve Carrot Flavour and Repel Pests
Chives (Allium schoenoprasum) planted alongside carrots help reduce carrot fly (Psila rosae) attack — a common problem in temperate European and North American gardens. The sulphur compounds in chive foliage mask the carrot scent the fly uses to locate host plants.
Extension observations indicate this works best when chives are allowed to flower slightly — the flowers also attract pollinators and beneficial hoverflies.
Some growers in continental climates report improved carrot sweetness when chives are interplanted, though the mechanism is not yet fully established scientifically.
Rule 13: Chamomile Benefits Almost Everything Nearby
German chamomile (Matricaria chamomilla) is sometimes called the ‘physician plant’ by experienced growers. It accumulates calcium and potassium from deeper soil layers, which become available to neighbouring shallow-rooted plants as the plant decomposes.
Chamomile also attracts hoverflies, parasitic wasps, and lacewings — all of which prey on common garden pests.
In cooler regions, it self-seeds freely and establishes a permanent presence with minimal management. Very common practice in biodynamic and organic growing systems across central Europe.
Rule 14: Sunflowers Attract Pollinators and Beneficial Predators
Tall sunflowers (Helianthus annuus) planted on the northern border of a vegetable garden provide multiple benefits without shading the main crop. Their large open flower heads attract bumblebees, honeybees, and solitary bee species that improve pollination for cucurbits, beans, and peppers.
Sunflower stems also host lacewing eggs and provide overwintering habitat for predatory beetles.
Field observations show that even three or four sunflower plants along a 10-metre (33-foot) bed edge measurably increases pollinator activity in cucumber and squash rows nearby.
Rule 15: Apply Companion Planting Within Your Climate Zone
Not every companion planting combination works equally well across all climates. In tropical regions (USDA zones 10–12), pest cycles are continuous year-round, so companion choices must account for a permanent pest population.
In arid climates, companion plants that compete for water — even beneficial ones — can reduce overall crop yield when irrigation is limited.
In Mediterranean climates with dry summers, aromatic herbs produce higher essential oil concentrations, making herb companions especially effective. In cooler zones (3–6), companion plants must establish quickly and deliver benefit within 8–14 weeks. Always adapt these rules to local conditions.
Companion Planting Chart: 12 Common Vegetables
- Basil – Repels aphids and improves flavour
- Marigold – Deters nematodes and pests
- Carrot – Loosens soil and saves space
- Parsley – Attracts beneficial insects
- Garlic – Repels spider mites
- Borage – Deters tomato hornworm
- Potato – Shares blight disease
- Fennel – Releases growth-inhibiting chemicals
- Corn – Attracts shared pests like earworm
- Brassicas (Cabbage, Broccoli) – Compete for nutrients
- Radish
- Beetroot
- Swiss Chard
60–90 cm (24–36 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Carrot – Slow root development; shares bed space without competing overhead
- Parsley – Steady beneficial insect attractor throughout main crop cycle
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Strong
Major pests reduced:
- Aphids
- Nematodes
- Spider Mites
- Tomato Hornworm
- Basil – Repels aphids and improves flavour
- Marigold – Deters nematodes
- Nasturtium – Trap crop for aphids
- Borage – Deters hornworm and attracts pollinators
- Potato – Shares blight disease
- Fennel – Inhibits growth
- Brassicas – Nutrient competition
- Radish
- Lettuce
- Spinach
45–60 cm (18–24 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Nasturtium – Full trap-crop function once vining mid-season
- Borage – Flowers mid-season; peak pollinator and hornworm deterrence
Protection strength: Strong
Major pests reduced:
- Aphids
- Nematodes
- Tomato Hornworm
- Basil – Classic pairing for flavour and pest control
- Marigold – Controls soil nematodes
- Garlic – Repels aphids and spider mites
- Carrot – Good space companion
- Potato – Shared blight risk
- Fennel – Growth inhibitor
- Corn – Attracts shared pests
- Beetroot
- Radish
60–90 cm (24–36 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Weak
Major pests reduced:
- Aphids
- Spider Mites
- Horseradish – Repels Colorado potato beetle
- Beans – Fix nitrogen in soil
- Marigold – Deters nematodes
- Cilantro – Attracts beneficial insects
- Tomato – Shared blight and disease risk
- Cucumber – Increases disease vulnerability
- Squash – Compete for nutrients
- Fennel – Inhibits potato growth
- Sunflower – Stunts potato plants
- Lettuce
- Spinach
- Radish
30–38 cm (12–15 in) apart, rows 75–90 cm (30–36 in)
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
Late season companions:
- Horseradish – Roots harvested in autumn; pest deterrence lasts all season
- Cilantro – Bolts to flower late; beneficial insect habitat after crop harvest
Protection strength: Moderate
Major pests reduced:
- Colorado Potato Beetle
- Nematodes
- Thyme – Repels whiteflies
- Summer Savory – Deters pests
- Marigold – Controls nematodes
- Dill – Attracts beneficial insects
- Squash – Compete aggressively for space
- Sunflower – Shades out vines
- Okra
- Beans
30–45 cm (12–18 in) apart, rows 0.9–1.2 m (3–4 ft)
Mid-season companions:
- Thyme – Spreads steadily; repellent effect strongest mid-season
- Summer Savory – Steady pest deterrence through the growing season
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
Protection strength: Moderate
Major pests reduced:
- Whiteflies
- Tomato – Loosens soil and saves space
- Rosemary – Repels carrot fly
- Sage – Repels carrot fly
- Onion – Mutual pest protection
- Leek – Repels carrot fly and onion fly
- Lettuce – Ground cover companion
- Dill – Cross-pollinates and inhibits growth
- Parsnip – Competes for space and nutrients
- Fennel – Inhibits carrot growth
- Radish
- Spinach
- Beans
5–10 cm (2–4 in) apart, rows 30 cm (12 in)
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
Late season companions:
- Rosemary – Perennial; provides carrot-fly and pest repellency into fall
- Sage – Perennial; repellent benefits continue after main crop peaks
- Onion – Bulbs mature late summer; deters pests through main crop season
- Leek – Hardy into fall; continues onion-fly deterrence late season
Protection strength: Moderate
Major pests reduced:
- Carrot Fly
- Onion Fly
- Radish – Deters cucumber beetles
- Nasturtium – Trap crop for aphids
- Beans – Fix nitrogen in soil
- Dill – Attracts beneficial insects (plant away from mature cucumbers)
- Sunflower – Provides trellis and shade
- Potato – Increases disease susceptibility
- Sage – Inhibits cucumber growth
- Fennel – Stunts growth
- Melon – Competes and shares pests
- Lettuce
- Corn
- Beets
90–150 cm (36–60 in) for bush; 30 cm (12 in) for vining on trellis
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Corn – Grows alongside; provides windbreak and structure mid-season
Late season companions:
- Sunflower – Continues providing windbreak and beneficial habitat after crop matures
Protection strength: Moderate
Major pests reduced:
- Cucumber Beetles
- Aphids
- Nasturtium – Repels squash bugs and aphids
- Borage – Deters squash vine borer
- Marigold – Repels pests
- Beans – Fix nitrogen
- Corn – Three Sisters companion
- Potato – Competition and shared diseases
- Fennel – Inhibits growth
- Pumpkin – Cross-pollinates, competes for space
- Lettuce
- Spinach
- Radish
60–90 cm (24–36 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Borage – Flowers mid-season; peak pollinator and hornworm deterrence
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Moderate
Major pests reduced:
- Aphids
- Squash Bugs
- Squash Vine Borers
- Borers
- Corn – Provides shade and windbreak
- Beans – Fix nitrogen; classic Three Sisters
- Nasturtium – Repels squash bugs
- Marigold – Pest deterrent
- Potato – Competition and disease
- Fennel – Inhibits growth
- Brassicas – Compete aggressively
- Radish
- Lettuce
1.5–1.8 m (5–6 ft) apart; vines need 5–9 sq m (50–100 sq ft)
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Corn – Grows alongside; provides windbreak and structure mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
- Nasturtium – Full trap-crop function once vining mid-season
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
Protection strength: Moderate
Major pests reduced:
- Squash Bugs
- Nasturtium – Trap crop for aphids
- Borage – Deters vine borers
- Marigold – Pest control
- Beans – Nitrogen fixation
- Fennel – Inhibits squash growth
- Potato – Shared disease risk
- Corn
- Radish
- Spinach
60–90 cm (24–36 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Borage – Flowers mid-season; peak pollinator and hornworm deterrence
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Moderate
Major pests reduced:
- Aphids
- Squash Vine Borers
- Borers
- Corn – Windbreak and shade
- Beans – Three Sisters nitrogen fixer
- Nasturtium – Pest deterrent
- Marigold – Repels pests
- Potato – Disease competition
- Fennel – Growth inhibitor
- Sunflower – Competes for nutrients
- Lettuce
- Radish
0.9–1.5 m (3–5 ft) apart; vines spread widely
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Corn – Grows alongside; provides windbreak and structure mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
- Nasturtium – Full trap-crop function once vining mid-season
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
Protection strength: Moderate
No specific pests identified from companion data.
- Carrot – Good soil companion
- Cucumber – Compatible nutrient needs
- Squash – Classic Three Sisters pairing
- Corn – Three Sisters support
- Radish – Deters bean beetles
- Strawberry – Mutual benefit
- Onion – Inhibits bean growth
- Garlic – Stunts beans
- Fennel – Growth inhibitor
- Beets – Inhibit each other
- Tomato
- Lettuce
- Spinach
10–15 cm (4–6 in) apart for bush; 15–20 cm (6–8 in) for pole
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Corn – Grows alongside; provides windbreak and structure mid-season
Protection strength: Weak
Major pests reduced:
- Bean Beetles
- Carrot – Companion root and leaf contrast
- Cucumber – Good nutrient compatibility
- Radish – Deters Mexican bean beetle
- Squash – Space efficient combination
- Onion – Inhibits bean germination and growth
- Garlic – Stunts bush beans
- Fennel – Growth inhibitor
- Lettuce
- Spinach
- Tomato
10–15 cm (4–6 in) apart, rows 45–60 cm (18–24 in)
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Cucumber – Simultaneous fruiting window with many warm-season crops
Protection strength: Weak
Major pests reduced:
- Bean Beetles
- Corn – Classic Three Sisters; corn provides trellis
- Squash – Three Sisters ground cover
- Radish – Deters bean pests
- Carrot – Root and leaf companion
- Onion – Inhibits bean growth
- Garlic – Stunts beans
- Beets – Mutual inhibition
- Sunflower – Competes for trellis and light
- Lettuce
- Tomato
15–25 cm (6–10 in) apart; needs 1.8–2.4 m (6–8 ft) trellis
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Corn – Grows alongside; provides windbreak and structure mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Protection strength: Weak
No specific pests identified from companion data.
- Carrot – Classic companion; complementary roots
- Radish – Pest deterrent and space efficient
- Lettuce – Shade tolerant companion
- Spinach – Cool season partners
- Turnip – Good cool-weather pairing
- Mint – Repels aphids (plant in containers)
- Onion – Inhibits pea growth
- Garlic – Stunts peas
- Fennel – Inhibits growth
- Leek – Inhibits peas
- Cucumber
- Beans
- Corn
5–10 cm (2–4 in) apart; needs trellis
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
- Turnip – Quick 45-day harvest; vacates bed for main crop
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Mint – Vigorous mid-season; keep contained to prevent takeover
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Moderate
Major pests reduced:
- Aphids
- Beans – Fix nitrogen and use corn as trellis
- Squash – Ground cover suppresses weeds
- Cucumber – Benefits from corn windbreak
- Sunflower – Provides additional windbreak
- Melon – Good space companion
- Tomato – Shared tomato fruitworm/earworm pest
- Celery – Inhibits corn growth
- Fennel – Inhibits growth
- Radish
- Lettuce
- Peas
23–30 cm (9–12 in) apart, rows 75–90 cm (30–36 in)
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Peas – Cool mid-season nitrogen fixer before warm crops take over
Late season companions:
- Sunflower – Continues providing windbreak and beneficial habitat after crop matures
Protection strength: Limited protection
No specific pests identified from companion data.
- Basil – Repels aphids and improves vigor
- Carrot – Space-efficient companion
- Marigold – Deters pests
- Onion – Pest deterrent
- Tomato – Compatible growing needs
- Fennel – Inhibits growth
- Brassicas – Attract shared pests
- Beans – Beans may inhibit pepper growth
- Squash
- Radish
- Lettuce
45–60 cm (18–24 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Carrot – Slow root development; shares bed space without competing overhead
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Moderate
Major pests reduced:
- Aphids
- Basil – Deters aphids, improves flavour
- Marigold – Pest control
- Carrots – Compact companion
- Tomato – Compatible heat-loving partners
- Fennel – Growth inhibitor
- Brassicas – Compete and attract pests
- Onion
- Garlic
- Squash
45–60 cm (18–24 in) apart
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Weak
Major pests reduced:
- Aphids
- Basil – Pest deterrent and flavour enhancer
- Marigold – Deters soil pests
- Carrot – Good root companion
- Tomato – Compatible growing requirements
- Fennel – Inhibits growth
- Brassicas – Competition and pest issues
- Apricot trees – Stunts peppers
- Onion
- Garlic
- Beans
35–45 cm (14–18 in) apart
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Carrot – Slow root development; shares bed space without competing overhead
- Beans – Fixes nitrogen actively while main crop is fruiting
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
No specific pests identified from companion data.
- Basil – Repels aphids and spider mites
- Marigold – Pest control
- Tarragon – Repels pests broadly
- Beans – Nitrogen fixation
- Catnip – Repels flea beetles
- Fennel – Inhibits growth
- Potato – Shared Colorado beetle and blight
- Corn – Attracts shared earworm pests
- Spinach
- Lettuce
- Squash
45–60 cm (18–24 in) apart
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Moderate
Major pests reduced:
- Aphids
- Spider Mites
- Flea Beetles
- Marigold – Repels cabbage worms
- Dill – Attracts wasps that prey on caterpillars
- Celery – Repels white cabbage butterfly
- Onion – Pest deterrent
- Nasturtium – Trap crop for aphids
- Sage – Deters cabbage pests
- Tomato – Inhibits tomato growth
- Strawberry – Inhibits each other
- Beans – Beans inhibit brassica growth
- Squash – Compete for nutrients
- Radish
- Beets
- Spinach
45–60 cm (18–24 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Celery – Slow grower; pest deterrence builds mid-season alongside main crop
- Nasturtium – Full trap-crop function once vining mid-season
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Sage – Perennial; repellent benefits continue after main crop peaks
Protection strength: Strong
Major pests reduced:
- Cabbage Worms
- Aphids
- Marigold – Deters cabbage pests
- Celery – Repels white butterfly
- Onion – Mutual pest deterrence
- Sage – Deters cabbage worms
- Dill – Attracts beneficial predatory wasps
- Tomato – Inhibits tomato nearby
- Strawberry – Mutual inhibition
- Squash – Competes for nutrients
- Radish
- Spinach
- Beets
45–60 cm (18–24 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Celery – Slow grower; pest deterrence builds mid-season alongside main crop
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Sage – Perennial; repellent benefits continue after main crop peaks
Protection strength: Strong
Major pests reduced:
- Cabbage Worms
- Dill – Attracts beneficial insects (mature dill only)
- Sage – Repels cabbage worms and moths
- Marigold – Pest deterrence
- Celery – Deters white butterfly
- Nasturtium – Trap crop for aphids
- Onion – Pest deterrent
- Tomato – Stunts tomato plants
- Strawberry – Mutual inhibition
- Beans – Inhibit each other
- Broccoli – Same pests; don't plant adjacent
- Beets
- Radish
- Spinach
30–60 cm (12–24 in) depending on variety
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Celery – Slow grower; pest deterrence builds mid-season alongside main crop
- Nasturtium – Full trap-crop function once vining mid-season
Late season companions:
- Sage – Perennial; repellent benefits continue after main crop peaks
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Strong
Major pests reduced:
- Cabbage Worms
- Aphids
- Marigold – Pest deterrence
- Nasturtium – Attracts aphids away from kale
- Dill – Attracts predatory wasps
- Onion – Deters cabbage pests
- Sage – Repels whiteflies
- Tomato – Inhibits growth
- Strawberry – Inhibits each other
- Beans – Compete and inhibit
- Beets
- Celery
- Cucumber
30–45 cm (12–18 in) apart
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Nasturtium – Full trap-crop function once vining mid-season
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Celery – Slow grower; pest deterrence builds mid-season alongside main crop
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Sage – Perennial; repellent benefits continue after main crop peaks
Protection strength: Moderate
Major pests reduced:
- Whiteflies
- Strawberry – Mutual benefit in cool weather
- Peas – Cool-season companions
- Radish – Companion and space filler
- Lettuce – Same needs and timing
- Garlic – Repels aphids from spinach
- Tomato – Spinach tolerates tomato shade
- Fennel – Inhibits most garden plants
- Potato – Competition issues
- Carrots
- Beets
- Onion
15 cm (6 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Peas – Cool mid-season nitrogen fixer before warm crops take over
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Weak
Major pests reduced:
- Aphids
- Carrot – Space-efficient companion
- Radish – Loosens soil and companion
- Strawberry – Mutual benefit
- Chives – Repels aphids
- Garlic – Aphid deterrent
- Dill – Beneficial insect attractor
- Celery – Inhibits lettuce
- Fennel – Inhibits nearly everything
- Parsley – Competes aggressively
- Cucumber
- Beans
- Peas
20–40 cm (8–16 in) depending on variety
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Chives – Established early; low-profile and harvest-ready in spring
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Beans – Fixes nitrogen actively while main crop is fruiting
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
Major pests reduced:
- Aphids
- Carrot – Efficient use of space
- Radish – Companion planting staple
- Garlic – Repels aphids
- Chives – Pest deterrent
- Fennel – Inhibits growth
- Celery – Inhibits lettuce
- Cucumber
- Beans
- Spinach
20–25 cm (8–10 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Chives – Established early; low-profile and harvest-ready in spring
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Beans – Fixes nitrogen actively while main crop is fruiting
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
Major pests reduced:
- Aphids
- Radish – Classic space companion
- Carrot – Root and leaf pairing
- Chives – Deter aphids
- Garlic – Repels pests
- Fennel – Inhibitor
- Celery – Inhibits lettuce
- Peas
- Beans
- Spinach
30–40 cm (12–16 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Chives – Established early; low-profile and harvest-ready in spring
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Peas – Cool mid-season nitrogen fixer before warm crops take over
- Beans – Fixes nitrogen actively while main crop is fruiting
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
Major pests reduced:
- Aphids
- Nasturtium – Companion and pest trap
- Lettuce – Same growth habit and timing
- Radish – Loosens soil
- Onion – Light pest deterrence
- Fennel – Inhibitor
- Brassicas (same family) – Shared pests
- Carrot
- Garlic
- Spinach
15 cm (6 in) apart; can be broadcast seeded
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
No specific pests identified from companion data.
- Beans – Nitrogen fixation benefits chard
- Brassicas – Companion planting
- Onion – Pest deterrent
- Lavender – Repels pests broadly
- Corn – Competes for nutrients
- Fennel – Inhibits growth
- Carrot
- Lettuce
- Spinach
15–30 cm (6–12 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Moderate
No specific pests identified from companion data.
- Onion – Pest deterrent
- Garlic – Repels aphids
- Lettuce – Efficient space companion
- Kohlrabi – Compatible garden companions
- Catnip – Repels flea beetles
- Beans – Mutual inhibition (especially pole beans)
- Mustard – Inhibits beet growth
- Fennel – Inhibitor
- Carrot
- Radish
- Spinach
8–10 cm (3–4 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
Major pests reduced:
- Aphids
- Flea Beetles
- Carrot – Breaks up soil for deeper carrot growth
- Cucumber – Deters cucumber beetles
- Lettuce – Classic companion planting pair
- Spinach – Cool-season companion
- Nasturtium – Pest deterrence partnership
- Beans – Space-efficient companion
- Fennel – Mutual inhibition
- Hyssop – Inhibits radish growth
- Tomato
- Pepper
- Peas
5–8 cm (2–3 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Nasturtium – Full trap-crop function once vining mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Moderate
Major pests reduced:
- Cucumber Beetles
- Peas – Cool-season companions
- Nasturtium – Pest trap
- Onion – Pest deterrent
- Mustard – Competes and shared pests
- Fennel – Inhibitor
- Potato – Disease issues
- Radish
- Carrot
- Spinach
10–15 cm (4–6 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Peas – Cool mid-season nitrogen fixer before warm crops take over
- Nasturtium – Full trap-crop function once vining mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Moderate
No specific pests identified from companion data.
- Carrot – Classic pairing; repel each other's pests
- Tomato – Pest deterrent
- Lettuce – Repels aphids
- Beets – Companion root vegetables
- Chamomile – Improves onion flavour
- Summer Savory – Deters onion fly
- Beans – Inhibits bean growth significantly
- Peas – Stunts peas
- Sage – Inhibits each other
- Asparagus – Inhibit each other
- Cucumber
- Spinach
- Pepper
10–15 cm (4–6 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Summer Savory – Steady pest deterrence through the growing season
- Cucumber – Simultaneous fruiting window with many warm-season crops
Protection strength: Strong
Major pests reduced:
- Aphids
- Onion Fly
- Carrot – Mutual pest repellence
- Beets – Compatible root companions
- Tomato – Light pest deterrent
- Chamomile – Improves flavour
- Beans – Inhibits bean germination
- Peas – Stunts growth
- Lettuce
- Spinach
- Pepper
10–15 cm (4–6 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
Protection strength: Moderate
No specific pests identified from companion data.
- Carrot – Deters carrot fly
- Tomato – Light aphid deterrent
- Lettuce – Space-efficient companion
- Strawberry – Deters slugs and pests
- Beans – Inhibits beans
- Peas – Stunts peas
- Spinach
- Beets
- Radish
5–8 cm (2–3 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
Protection strength: Moderate
Major pests reduced:
- Carrot Fly
- Aphids
- Tomato – Repels spider mites and aphids
- Roses – Repels aphids and black spot
- Carrots – Pest deterrent
- Spinach – Repels aphids
- Fruit trees – General pest deterrent
- Beans – Inhibits bean growth
- Peas – Stunts peas
- Parsley – Inhibits each other
- Asparagus – Inhibit each other
- Lettuce
- Beets
- Cucumber
10–15 cm (4–6 in) apart
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Cucumber – Simultaneous fruiting window with many warm-season crops
Protection strength: Strong
Major pests reduced:
- Aphids
- Spider Mites
- Carrot – Classic pairing; repel each other's flies
- Onion – Companion allium plants
- Celery – Space-efficient companion
- Beans – Inhibits beans
- Peas – Inhibit each other
- Garlic – Competition (too similar)
- Lettuce
- Radish
- Spinach
15 cm (6 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Celery – Slow grower; pest deterrence builds mid-season alongside main crop
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Weak
No specific pests identified from companion data.
- Carrot – Classic allium-root companion
- Tomato – Light pest deterrent
- Strawberry – Deters pests
- Chamomile – Flavour companion
- Beans – Inhibits beans
- Peas – Inhibit each other
- Lettuce
- Spinach
- Beets
15–20 cm (6–8 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
Protection strength: Moderate
No specific pests identified from companion data.
- Basil – Repels pests
- Marigold – Pest deterrence
- Peppers – Compatible heat-loving companions
- Sunflower – Attracts pollinators
- Melons – Space-compatible heat-lovers
- Squash – Compete for space and nutrients
- Sweet potato – Root competition
- Beans
- Corn
- Tomato
30–45 cm (12–18 in) apart
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
- Corn – Grows alongside; provides windbreak and structure mid-season
Late season companions:
- Sunflower – Continues providing windbreak and beneficial habitat after crop matures
Protection strength: Moderate
No specific pests identified from companion data.
- Tomato – Repels white cabbage butterfly
- Beans – Nitrogen enrichment
- Leek – Space-efficient companion
- Spinach – Cool-season pairing
- Cabbage – Celery deters cabbage pests
- Corn – Inhibits celery growth
- Aster – Inhibits growth
- Lettuce – Inhibits each other
- Onion
- Carrot
- Cucumber
20–30 cm (8–12 in) apart
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Carrot – Slow root development; shares bed space without competing overhead
- Cucumber – Simultaneous fruiting window with many warm-season crops
Late season companions:
- Leek – Hardy into fall; continues onion-fly deterrence late season
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Moderate
No specific pests identified from companion data.
- Tomato – Mutual benefit; tomato repels asparagus beetle
- Basil – Repels asparagus beetles
- Marigold – Deters pests
- Parsley – Good companion
- Nasturtium – Beneficial insect attractor
- Onion – Inhibit each other
- Garlic – Inhibit each other
- Potato – Competition and disease risk
- Strawberry
- Spinach
- Beets
30–45 cm (12–18 in) apart; rows 1.2–1.5 m (4–5 ft)
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Parsley – Steady beneficial insect attractor throughout main crop cycle
- Nasturtium – Full trap-crop function once vining mid-season
Protection strength: Moderate
No specific pests identified from companion data.
- Tarragon – Companion herb
- Marigold – Pest deterrence
- Sunflower – Attracts pollinators
- Beans – Competition
- Potato – Disease and nutrient competition
- Asparagus
- Tomato
- Onion
1.2–1.8 m (4–6 ft) apart (large perennial plant)
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
Late season companions:
- Sunflower – Continues providing windbreak and beneficial habitat after crop matures
- Asparagus – Perennial; fern fronds offer late-season cover and soil benefit
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Weak
No specific pests identified from companion data.
- Marigold – Deters cabbage worms and whiteflies
- Nasturtium – Trap crop for aphids
- Dill – Attracts parasitic wasps
- Sage – Repels moths
- Thyme – Deters cabbage worms
- Tomato – Inhibits brassicas
- Strawberry – Inhibit each other
- Beans – Inhibit each other
- Kohlrabi – Competition and shared disease
- Beets
- Radish
- Spinach
45–60 cm (18–24 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Nasturtium – Full trap-crop function once vining mid-season
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Thyme – Spreads steadily; repellent effect strongest mid-season
Late season companions:
- Sage – Perennial; repellent benefits continue after main crop peaks
Protection strength: Strong
Major pests reduced:
- Whiteflies
- Cabbage Worms
- Aphids
- Marigold – Pest deterrence
- Onion – Deters cabbage pests
- Nasturtium – Trap crop for aphids
- Thyme – Deters worms and moths
- Tomato – Inhibits nearby tomato
- Beans – Inhibit each other
- Strawberry – Mutual inhibition
- Beets
- Celery
- Radish
45–60 cm (18–24 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Nasturtium – Full trap-crop function once vining mid-season
- Thyme – Spreads steadily; repellent effect strongest mid-season
- Celery – Slow grower; pest deterrence builds mid-season alongside main crop
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Strong
Major pests reduced:
- Aphids
- Nasturtium – Companion pest trap
- Onion – Pest deterrent
- Radish – Space-efficient cool-season companion
- Beans – Mutual inhibition
- Turnip – Shared brassica pests
- Fennel – Inhibitor
- Spinach
- Lettuce
- Carrot
15–30 cm (6–12 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Moderate
No specific pests identified from companion data.
- Peas – Nitrogen fixation companion
- Onion – Pest deterrent
- Radish – Space marker and loosening companion
- Carrot – Competes for similar nutrients and space
- Fennel – Inhibitor
- Lettuce
- Spinach
- Garlic
15 cm (6 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Peas – Cool mid-season nitrogen fixer before warm crops take over
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Weak
No specific pests identified from companion data.
- Nasturtium – Pest deterrence
- Onion – Companion root vegetable
- Peas – Nitrogen fixation
- Turnip – Same brassica family; same pests
- Mustard – Competition
- Fennel – Inhibitor
- Spinach
- Carrot
- Radish
15–20 cm (6–8 in) apart
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Peas – Cool mid-season nitrogen fixer before warm crops take over
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Weak
No specific pests identified from companion data.
- Carrot – Space companion
- Radish – Cool-season pairing
- Onion – Pest deterrent
- Fennel – Inhibitor
- Celery – Competition
- Lettuce
- Spinach
- Garlic
23–30 cm (9–12 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Weak
No specific pests identified from companion data.
- Dill – Compatible umbellifers (keep separate to avoid cross-pollination)
- Coriander – Some compatibility reported
- Tomato – Strongly inhibits tomato
- Pepper – Inhibits peppers
- Beans – Stunts beans
- Peas – Inhibits peas
- Brassicas – Inhibits cabbage family
- Kohlrabi – Growth inhibition
- Potatoes – Inhibits potatoes
- Nearly all vegetables – Fennel is allelopathic
30–45 cm (12–18 in); best planted in isolated bed
Mid-season companions:
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
Protection strength: Limited protection
No specific pests identified from companion data.
- Onion – Mutual pest deterrence
- Beets – Compatible root companions
- Cucumber – Space-efficient pairing
- Lettuce – Ground cover companion
- Tomato – Inhibits kohlrabi growth
- Pole Beans – Compete for nutrients
- Fennel – Inhibits growth
- Pepper – Poor compatibility
- Radish
- Spinach
- Swiss Chard
15–23 cm (6–9 in) apart, rows 30 cm (12 in)
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Cucumber – Simultaneous fruiting window with many warm-season crops
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Weak
No specific pests identified from companion data.
- Nasturtium – Trap crop for aphids
- Garlic – Repels aphids and cabbage worms
- Onion – Pest deterrence
- Dill – Attracts beneficial insects
- Tomato – Poor companions
- Pole Beans – Inhibit bok choy
- Fennel – Inhibits growth
- Strawberry – Poor compatibility
- Lettuce
- Spinach
- Radish
15–30 cm (6–12 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Moderate
Major pests reduced:
- Aphids
- Cabbage Worms
- Basil – Repels pests and improves growth
- Marigold – Deters nematodes and pests
- Carrot – Good soil companion
- Borage – Attracts pollinators
- Potato – Shared blight and disease risk
- Fennel – Inhibits growth
- Brassicas – Compete for nutrients
- Corn – Attracts shared pests
- Radish
- Spinach
- Lettuce
60–90 cm (24–36 in) apart; needs two plants to set fruit
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Carrot – Slow root development; shares bed space without competing overhead
- Borage – Flowers mid-season; peak pollinator and hornworm deterrence
Protection strength: Moderate
Major pests reduced:
- Nematodes
- Carrot – Repels carrot fly
- Tomato – Repels aphids
- Broccoli – Deters aphids and cabbage worms
- Rose (ornamental) – Repels aphids
- Apple Tree (orchard) – Repels apple scab
- Beans – Inhibit bean growth
- Peas – Stunts peas
- Lettuce
- Spinach
- Pepper
10–15 cm (4–6 in) apart; clump-forming
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
Protection strength: Strong
Major pests reduced:
- Carrot Fly
- Aphids
- Cabbage Worms
- Potato – Repels Colorado potato beetle
- Fruit Trees – Repels borers and disease
- Rhubarb – Some pest deterrence reported
- Kale – Inhibits growth
- Broccoli – Can compete aggressively
- Beans
- Corn
- Lettuce
60–75 cm (24–30 in) apart; spreads vigorously
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Corn – Grows alongside; provides windbreak and structure mid-season
Protection strength: Moderate
Major pests reduced:
- Colorado Potato Beetle
- Borers
- Carrot – Classic companion; complementary roots
- Lettuce – Shade tolerant companion below trellis
- Radish – Deters pests and efficient space use
- Spinach – Cool-season partners
- Turnip – Good cool-weather pairing
- Mint – Repels aphids (plant in containers)
- Onion – Inhibits pea growth
- Garlic – Stunts peas
- Leek – Inhibits peas
- Fennel – Inhibits growth
- Cucumber
- Beans
- Corn
5–8 cm (2–3 in) apart; needs trellis 1.2–1.8 m (4–6 ft) tall
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
- Turnip – Quick 45-day harvest; vacates bed for main crop
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Mint – Vigorous mid-season; keep contained to prevent takeover
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Moderate
Major pests reduced:
- Aphids
- Beans – Nitrogen improves radicchio flavour
- Carrot – Root space companion
- Radish – Pest deterrence
- Garlic – Repels aphids
- Fennel – Inhibits chicory family plants
- Sunflower – Allelopathic chemicals
- Lettuce
- Spinach
- Endive
20–30 cm (8–12 in) apart
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
Major pests reduced:
- Aphids
- Onion – Pest deterrence
- Dill – Attracts beneficial wasps
- Nasturtium – Trap crop for aphids
- Garlic – Repels aphids and cabbage worms
- Tomato – Poor companion for brassicas
- Beans – Inhibit brassica growth
- Fennel – Inhibits growth
- Strawberry – Poor compatibility
- Lettuce
- Spinach
- Radish
6–8 inches (15–20 cm) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Nasturtium – Full trap-crop function once vining mid-season
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Moderate
Major pests reduced:
- Aphids
- Cabbage Worms
- Basil – Repels pests and attracts pollinators
- Marigold – Deters nematodes and pests
- Corn – Provides trellis and windbreak
- Nasturtium – Trap crop for aphids
- Beans – Nitrogen fixation
- Potato – Competition and disease risk
- Pumpkin – Cross-pollinates and competes
- Fennel – Inhibits growth
- Radish
- Spinach
- Lettuce
45–60 cm (18–24 in) apart; needs trellis
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Corn – Grows alongside; provides windbreak and structure mid-season
- Nasturtium – Full trap-crop function once vining mid-season
Protection strength: Moderate
Major pests reduced:
- Nematodes
- Aphids
- Marigold – Pest deterrence
- Basil – Repels aphids and whiteflies
- Beans – Nitrogen fixation
- Nasturtium – Trap crop
- Potato – Shared disease risk
- Pumpkin – Competition and cross-pollination
- Fennel – Inhibits growth
- Corn
- Radish
- Spinach
1.5–2 m (5–6 feet) apart; vigorous climber
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Beans – Fixes nitrogen actively while main crop is fruiting
- Nasturtium – Full trap-crop function once vining mid-season
Protection strength: Moderate
Major pests reduced:
- Aphids
- Whiteflies
- Marigold – Deters pests
- Basil – Repels whiteflies
- Beans – Fixes nitrogen
- Nasturtium – Attracts pollinators
- Potato – Disease issues
- Pumpkin – Competition
- Fennel – Inhibitor
- Corn
- Radish
- Lettuce
60–90 cm (24–36 in); needs trellis
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Beans – Fixes nitrogen actively while main crop is fruiting
- Nasturtium – Full trap-crop function once vining mid-season
Protection strength: Moderate
Major pests reduced:
- Whiteflies
- Marigold – Pest control
- Basil – Repels insects
- Beans – Nitrogen fixer
- Pumpkin – Competition
- Potato – Disease
- Corn
- Radish
- Nasturtium
1–1.5 m (3–5 feet); trellis essential
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Beans – Fixes nitrogen actively while main crop is fruiting
- Corn – Grows alongside; provides windbreak and structure mid-season
Protection strength: Weak
No specific pests identified from companion data.
- Marigold – Deters nematodes
- Basil – Repels pests
- Beans – Nitrogen fixation
- Nasturtium – Pollinator attractor
- Potato – Disease risk
- Pumpkin – Competition for space
- Corn
- Sunflower
- Radish
1 m (3 feet) apart; needs strong trellis
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Beans – Fixes nitrogen actively while main crop is fruiting
- Nasturtium – Full trap-crop function once vining mid-season
Late season companions:
- Sunflower – Continues providing windbreak and beneficial habitat after crop matures
Protection strength: Moderate
Major pests reduced:
- Nematodes
- Marigold – Pest deterrence
- Beans – Fixes nitrogen to feed heavy yam feeders
- Taro – Companion tropical root
- Nasturtium – Deters pests
- Sweet Potato – Competition for space and nutrients
- Fennel – Inhibitor
- Corn
- Squash
- Okra
30–40 cm (12–16 in) apart; needs staking
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
- Nasturtium – Full trap-crop function once vining mid-season
- Corn – Grows alongside; provides windbreak and structure mid-season
Protection strength: Moderate
No specific pests identified from companion data.
- Beans – Fixes nitrogen for heavy-feeding taro
- Sweet Potato – Companion tropical root
- Marigold – Pest deterrence
- Lemongrass – Deters pests
- Potato – Disease and nutrient competition
- Fennel – Inhibitor
- Yam
- Okra
- Corn
45–60 cm (18–24 in) apart
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Corn – Grows alongside; provides windbreak and structure mid-season
Protection strength: Moderate
No specific pests identified from companion data.
- Tomato – Repels aphids and whiteflies
- Basil – Companion aromatic herb
- Cabbage – Deters caterpillars
- Eggplant – Repels pests broadly
- Fennel – Allelopathic competition
- Beans
- Corn
- Marigold
60–90 cm (24–36 in) apart; clump-forming
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Beans – Fixes nitrogen actively while main crop is fruiting
- Corn – Grows alongside; provides windbreak and structure mid-season
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
Protection strength: Moderate
Major pests reduced:
- Aphids
- Whiteflies
- Basil – Repels aphids and spider mites
- Marigold – Pest control
- Tarragon – Repels pests broadly
- Beans – Nitrogen fixation
- Catnip – Repels flea beetles
- Fennel – Inhibits growth
- Potato – Shared Colorado beetle and blight
- Corn – Attracts shared earworm pests
- Spinach
- Lettuce
- Squash
45–60 cm (18–24 in) apart
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Moderate
Major pests reduced:
- Aphids
- Spider Mites
- Flea Beetles
- Basil – Deters aphids, improves flavour
- Marigold – Pest control
- Carrot – Compact root companion
- Tomato – Compatible heat-loving partners
- Coriander – Attracts beneficial insects
- Fennel – Growth inhibitor
- Brassicas – Compete and attract pests
- Apricot trees – Stunts peppers
- Onion
- Garlic
- Squash
45–60 cm (18–24 in) apart
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Weak
Major pests reduced:
- Aphids
- Tomato – Attracts beneficial insects
- Spinach – Compatible cool-season companion
- Beans – Mutually beneficial
- Cabbage – Deters aphids and cabbage worms
- Carrot – Attracts carrot fly predators
- Potato – Attracts beneficial insects
- Fennel – Cross-pollinates and competes
- Dill – Cross-pollinates when both flowering
- Lettuce
- Radish
- Beets
15–20 cm (6–8 in) apart
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Carrot – Slow root development; shares bed space without competing overhead
Protection strength: Weak
Major pests reduced:
- Aphids
- Cabbage Worms
- Corn – Fixes nitrogen for corn
- Onion – Companion herb
- Potato – Pest deterrence
- Carrot – Beneficial insect attractor
- Fennel – Inhibitor
- Brassicas – Competition
- Spinach
- Radish
- Tomato
10–15 cm (4–6 in) apart
Early season companions:
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Corn – Grows alongside; provides windbreak and structure mid-season
- Carrot – Slow root development; shares bed space without competing overhead
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Weak
No specific pests identified from companion data.
- Beans – Nitrogen companion under canopy
- Basil – Companion aromatic
- Marigold – Pest deterrence at base
- Taro – Shade-tolerant companion
- Other large trees – Competition for canopy and roots
- Potato – Root competition
- Okra
- Corn
- Yam
2–3 m (6–10 feet) apart; fast-growing tree
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Corn – Grows alongside; provides windbreak and structure mid-season
Protection strength: Weak
No specific pests identified from companion data.
- Basil – Companion aromatic
- Marigold – Pest deterrence
- Beans – Ground-level nitrogen fixer
- Large fruit trees – Root and canopy competition
- Okra
- Yam
- Taro
2–3 m (6–10 feet); prune to maintain height
Mid-season companions:
- Basil – Grows alongside all season; peak pest repellency mid-summer
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Weak
No specific pests identified from companion data.
- Carrot – Breaks and loosens deep soil layers
- Lettuce – Companion planting pair
- Cucumber – Deters cucumber beetles
- Beans – Space-efficient companion
- Nasturtium – Pest deterrence partnership
- Fennel – Mutual inhibition
- Hyssop – Inhibits radish
- Tomato
- Pepper
- Spinach
15–20 cm (6–8 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
Mid-season companions:
- Carrot – Slow root development; shares bed space without competing overhead
- Cucumber – Simultaneous fruiting window with many warm-season crops
- Beans – Fixes nitrogen actively while main crop is fruiting
- Nasturtium – Full trap-crop function once vining mid-season
Protection strength: Moderate
Major pests reduced:
- Cucumber Beetles
- Nasturtium – Trap crop for aphids
- Garlic – Repels aphids and cabbage worms
- Onion – Pest deterrence
- Dill – Attracts beneficial insects
- Tomato – Poor companions
- Pole Beans – Inhibit pak choi
- Fennel – Inhibits growth
- Strawberry – Poor compatibility
- Lettuce
- Spinach
- Radish
15–30 cm (6–12 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Nasturtium – Full trap-crop function once vining mid-season
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
Late season companions:
- Garlic – Matures late; soil benefits persist after harvest
- Onion – Bulbs mature late summer; deters pests through main crop season
Protection strength: Moderate
Major pests reduced:
- Aphids
- Cabbage Worms
- Marigold – Deters cabbage worms and beetles
- Onion – Pest deterrence
- Dill – Attracts beneficial wasps
- Nasturtium – Trap crop for aphids
- Garlic – Repels pests
- Tomato – Poor companion for brassicas
- Beans – Inhibit each other
- Fennel – Growth inhibitor
- Strawberry – Poor compatibility
- Lettuce
- Spinach
- Radish
30–45 cm (12–18 in) apart
Early season companions:
- Lettuce – Ready in 45–60 days; clears space as main crop grows
- Spinach – Bolts in heat; harvested early before summer crops peak
- Radish – Matures in 25–30 days; harvests before most crops establish
Mid-season companions:
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Dill – Attracts beneficials at mid-season bloom; keep from maturing near carrots
- Nasturtium – Full trap-crop function once vining mid-season
Late season companions:
- Onion – Bulbs mature late summer; deters pests through main crop season
- Garlic – Matures late; soil benefits persist after harvest
Protection strength: Strong
Major pests reduced:
- Cabbage Worms
- Aphids
- Corn – Provides trellis; Three Sisters-style
- Squash – Ground cover companion
- Marigold – Pest deterrence
- Radish – Deters bean pests
- Onion – Inhibits bean growth
- Garlic – Stunts beans
- Fennel – Growth inhibitor
- Lettuce
- Tomato
- Cucumber
10–15 cm (4–6 in) apart; needs 1.5 m trellis
Early season companions:
- Radish – Matures in 25–30 days; harvests before most crops establish
- Lettuce – Ready in 45–60 days; clears space as main crop grows
Mid-season companions:
- Corn – Grows alongside; provides windbreak and structure mid-season
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Cucumber – Simultaneous fruiting window with many warm-season crops
Protection strength: Moderate
No specific pests identified from companion data.
- Corn – Trellis provider
- Marigold – Pest deterrence
- Nasturtium – Companion and pollinator attractor
- Onion – Inhibits legumes
- Garlic – Stunts beans
- Squash
- Cucumber
- Taro
20–30 cm (8–12 in) apart; needs trellis
Mid-season companions:
- Corn – Grows alongside; provides windbreak and structure mid-season
- Marigold – Continuous bloomer; maximum nematode deterrence mid-season
- Nasturtium – Full trap-crop function once vining mid-season
- Cucumber – Simultaneous fruiting window with many warm-season crops
Protection strength: Weak
No specific pests identified from companion data.
- Taro – Classic tropical companion
- Beans – Ground-level nitrogen fixer
- Sweet Potato – Shade-tolerant ground cover
- Lemongrass – Perimeter pest deterrent
- Other large fruit trees – Competition for space and water
- Potato – Disease risk
- Yam
- Okra
- Moringa
2–4 m (6–13 feet) apart
Mid-season companions:
- Beans – Fixes nitrogen actively while main crop is fruiting
Protection strength: Weak
No specific pests identified from companion data.
What Is Companion Planting?
Companion planting is the practice of growing different plants in close proximity so that each benefits the other. This traditional garden technique has been used for centuries by home gardeners and farmers across the world to improve yields, manage pests, and make the most of available growing space. When chosen thoughtfully, companion plants can replace or reduce the need for chemical fertilisers and pesticides, making your vegetable garden healthier and more sustainable.
The concept is rooted in natural ecology — in the wild, plants evolved alongside specific neighbours and developed complementary relationships. By mimicking these relationships in your garden, you work with nature rather than against it. Some plants release chemicals through their roots that improve soil conditions or deter harmful insects. Others provide physical benefits like shade, windbreaks, or climbing structures. Still others attract the beneficial insects that pollinate crops and prey on destructive pests.
One of the most famous examples of companion planting is the Native American "Three Sisters" — corn, beans, and squash grown together. The corn provides a natural trellis for the beans to climb, the beans fix nitrogen from the air into the soil to feed the other two plants, and the squash spreads along the ground with its large leaves, blocking sunlight from weeds and keeping soil moist. This trio has fed communities for thousands of years and remains a highly effective combination for modern home gardens worldwide.
Benefits of Companion Planting for Home Gardeners
For home gardeners everywhere — from tropical Asia to temperate Europe, subtropical Africa to the Americas — companion planting offers a wide range of practical benefits. Pest management is one of the most compelling reasons to try it. Many herbs and flowers, including marigolds, basil, and nasturtiums, naturally repel common garden pests when planted near vegetables. This means less damage to your crops without reaching for a spray bottle. At the same time, certain companion plants attract beneficial insects like ladybugs, lacewings, and parasitic wasps that feed on aphids, caterpillars, and other destructive bugs.
Companion planting also helps maximise space in small gardens. Fast-maturing plants like radishes and daikon can be grown between slower-growing vegetables, filling gaps that would otherwise sit empty. Tall plants provide welcome shade for heat-sensitive crops like lettuce during the hottest weeks of the year. Ground-covering plants like squash or sweet potato suppress weed growth, reducing weeding time and retaining soil moisture.
Soil health is another significant benefit. Legumes — beans, peas, yard-long beans, and similar plants — host bacteria in their roots that convert atmospheric nitrogen into a form plants can absorb. When their roots decompose at the end of the season, they enrich the soil for whatever is planted next. This natural fertilisation can reduce the need for added nitrogen fertilisers — important in all growing regions, and especially in areas where synthetic inputs are expensive or hard to source.
Companion Planting in Tropical and Subtropical Gardens
Gardeners in tropical and subtropical climates — across South Asia, Southeast Asia, Africa, the Pacific Islands, the Caribbean, and Latin America — have a rich tradition of companion planting adapted to year-round growing conditions. Crops like bitter gourd, bottle gourd, ridge gourd, snake gourd, yard-long beans, winged beans, taro, yam, moringa, and plantain all have companion plant pairings suited to warm, humid environments. Many of these crops are heavy feeders that benefit enormously from nitrogen-fixing legume companions, and from aromatic pest deterrents like lemongrass and basil planted at the garden's border.
In tropical polyculture systems, it is common to layer companions vertically: tall crops like moringa or plantain provide canopy and wind protection; mid-height crops like okra and yam benefit from partial shade; and low-growing companions like sweet potato, taro, or ground-level beans fill the understory, suppress weeds, and enrich the soil. This multi-storey approach maximises biodiversity, conserves moisture, and reduces the risk of total crop failure from a single pest or disease.
The following chart covers the most widely grown vegetables and their confirmed good and bad companions based on grower observation and agricultural research. Scientific names are included for clarity. Bad companion pairings reflect either allelopathic interference, shared disease risk, or direct competition for the same soil nutrients.
| Vegetable | Good Companions | Bad Companions | Why It Works |
| Tomato (Solanum lycopersicum) | Basil, Carrots, Marigold | Fennel, Brassicas | Basil repels aphids & spider mites; marigolds deter nematodes |
| Beans (Phaseolus vulgaris) | Corn, Squash, Carrots | Onion, Fennel, Garlic | Fixes atmospheric nitrogen (N); corn provides natural trellis |
| Carrots (Daucus carota) | Tomatoes, Leeks, Chives | Dill (mature), Parsnip | Leeks repel carrot fly; chives improve flavour & root yield |
| Cabbage (Brassica oleracea) | Dill, Chamomile, Mint | Tomatoes, Strawberries | Dill attracts beneficial wasps; mint deters cabbage white butterfly |
| Cucumber (Cucumis sativus) | Radish, Nasturtium, Beans | Potatoes, Aromatic Herbs | Nasturtium acts as trap crop for aphids; radish deters cucumber beetles |
| Corn (Zea mays) | Beans, Squash, Borage | Tomatoes, Brassicas | The Three Sisters system: corn = trellis, beans = nitrogen, squash = ground cover |
| Lettuce (Lactuca sativa) | Chives, Garlic, Carrots | Celery, Parsley | Garlic deters lettuce aphids; carrots loosen soil around roots |
| Pepper (Capsicum annuum) | Basil, Carrots, Tomatoes | Fennel, Brassicas | Basil may improve fruit set; tomatoes share similar water and heat needs |
| Squash (Cucurbita spp.) | Corn, Beans, Nasturtium | Potatoes | Large leaves suppress weeds; nasturtium repels squash bugs |
| Garlic (Allium sativum) | Roses, Brassicas, Tomatoes | Beans, Peas, Parsley | Releases sulphur compounds that deter a wide range of fungal diseases |
| Potatoes (Solanum tuberosum) | Horseradish, Beans, Marigold | Tomatoes, Cucumber, Squash | Horseradish may improve disease resistance; avoid Solanaceae cross-infection |
Now that you know the rules and the chart, use this free garden planner below to find the best and worst companions for any vegetable in your garden — instantly.
Garden Planner Tool
Answer a few questions to get your personalised garden plan with plant recommendations, spacing, and timelines.
1 What Do You Want to Grow?
2 Select Garden Type
3 Enter Garden Size
4 Sunlight Exposure
5 Growing Season
Other plants that suit your conditions — swap any recommended plant for these.
Once you have your companion combinations ready, the next step is knowing how climate and growing season affect which pairings work best in your region.
Companion Planting Across Climate Zones
Tropical climates (zones 10–12): Pest pressure is continuous and intense. Marigold borders, nasturtium trap crops, and allium companions are critical. Mulching ground covers help retain moisture in rainfall above 2,000 mm (79 inches) annually.
Subtropical zones (8–10): Across India, southern China, Florida, and northern Australia, the long growing season allows multi-layer companion planting — tall crops like corn above, main vegetables in the middle, and ground-cover companions like squash below.
Temperate zones (5–8): The most documented companion planting combinations apply here. Three Sisters planting, basil-tomato pairings, and herb borders for brassicas all perform consistently from 10°C to 28°C (50°F to 82°F).
Continental and arid zones (3–6, 7–9): Choose drought-tolerant companions — thyme, chives, sage, and marigold. Drip irrigation at the base of companion rows maintains their effectiveness without overwatering.
Common Companion Planting Mistakes to Avoid
- Planting fennel in the main vegetable bed — one of the most frequent mistakes seen in beginner gardens worldwide
- Mixing all Solanaceae family plants together without considering shared disease risk
- Placing alliums directly alongside beans or peas, disrupting nitrogen fixation
- Ignoring timing — planting mature dill next to established carrots instead of young seedlings
- Overcrowding companion plants at the expense of airflow, which increases fungal disease pressure
- Applying companion planting advice from one climate region to a completely different growing zone without adjustment
- Assuming all aromatic herbs deter all pests — specificity matters in plant selection
Key Takeaways
- Companion planting works through plant chemistry, root interaction, and pest confusion — not superstition
- Marigolds, nasturtiums, and aromatic herbs are among the most versatile companion plants for most vegetable gardens
- Fennel and mature alliums are the two most frequently misused companions — plant them with care
- Legumes are the most important nitrogen-contributing companions — protect their root nodules
- The Three Sisters system is one of the most complete, self-sustaining companion planting strategies available
- Always adapt companion planting choices to your USDA hardiness zone and local soil and pest conditions
- Companion planting reduces but does not eliminate the need for other IPM strategies, crop rotation, or compost
Proper watering is equally important when growing companion plants together, and tools like a plant watering calculator can help estimate moisture needs for mixed crops.
Frequently Asked Questions About Companion Planting
1. Does companion planting actually work, or is it just garden folklore?
Companion planting has a genuine scientific basis for many combinations, though the strength of evidence varies.
Marigold nematode suppression, legume nitrogen fixation, and allium antifungal effects are all well-documented, as explained in extension research such as this companion planting research overview.
Some older plant combination claims lack rigorous data and may be overstated. The safest approach is to apply the rules with the strongest scientific backing first — these are also the most consistently reported by growers worldwide.
2. How close do companion plants need to be to each other to work?
For aromatic deterrence, companion plants need to be within 30–60 cm (12–24 inches) of the target crop for volatile compounds to create an effective scent barrier.
For root-based effects like nitrogen fixation or nematode suppression, direct root overlap within the same soil zone is required. Trap crops like nasturtiums can work at 60–90 cm (24–36 inches) because pests are drawn toward them, not pushed away.
3. Can I apply companion planting in a small urban garden or raised bed?
Raised bed gardening is ideal for companion planting. It allows precise plant placement and consistent soil conditions. Many growers apply the shallow-root/deep-root rule effectively in beds as small as 60 cm × 120 cm (2 × 4 feet).
Choose compact companion varieties — dwarf marigolds, chive clumps, or bush basil. Container growing also works: pairing basil with a potted tomato on a balcony is a simple and effective start.
4. What is the best companion plant for tomatoes?
Basil is the most widely recommended companion for tomatoes, based on consistent grower reports and research into volatile compound interactions. Marigolds are a close second for their nematode-suppressing roots and aphid deterrence.
Carrots improve soil aeration around tomato roots. Avoid planting tomatoes near brassicas, fennel, or potatoes. In warm climates, basil-tomato combinations are especially effective during peak summer heat.
5. Should I follow companion planting rules for organic growing?
Companion planting is especially valuable in organic systems where synthetic pesticide and fertiliser use is restricted. Legume nitrogen fixation directly replaces synthetic nitrogen (N) input. Herb and flower companions reduce the need for approved organic sprays.
The FAO and national extension services include companion planting within formal IPM frameworks for certified organic production. Extension observations indicate that organic gardeners who apply these rules consistently rely on intervention sprays far less frequently.
6. How does companion planting help with pest control specifically?
Companion planting disrupts pest behaviour through three main mechanisms. Aromatic plants confuse pests that locate crops by scent. Trap crops like nasturtiums draw pests away from the main crop, concentrating them for easier management.
Flowering companions attract beneficial predatory insects — ladybirds, parasitic wasps, lacewings, and hoverflies — that feed on common garden pests. Together, these three mechanisms reduce pest populations significantly when applied consistently.
7. When is the best time to start companion planting?
Planning before the growing season begins gives the best results. In temperate regions, map companion combinations in late winter or early spring, before frost dates pass.
Common beginner mistake: planting companion flowers too late, so they establish after pest pressure has already arrived. Marigolds and basil need to be started indoors 6–8 weeks before outdoor planting to be ready alongside vegetable transplants.
3 Most Useful Companion Plants at a Glance
Quick reference — most versatile companions for vegetable gardens:
- Marigold — broad-spectrum pest suppression, nematode control, whitefly deterrence
- Basil — aromatic insect deterrence, particularly for tomato crops
- Beans — atmospheric nitrogen fixation, feeding heavy feeders naturally
Sources Used in This Guide
This guide is based on:
- University extension companion planting guides (UK, US, Australia, India)
- FAO integrated pest management manuals
- Organic farming observations across temperate and tropical growing regions
- Seed production spacing recommendations and crop interaction research
Conclusion
Companion planting works best when applied as part of a complete garden plan rather than relying on individual plant pairings in isolation.
Start with a few proven combinations, observe results across one or two growing seasons, and expand gradually. Over time, these natural plant relationships can significantly improve garden health, reduce pest pressure, and improve overall productivity.
Note: Companion planting improves growing success but should be combined with proper spacing, soil fertility management, and crop rotation for best results. Results may vary by climate zone, soil type, and local pest pressure.