How to Grow Heirloom Tomatoes from Seeds-A Guide

How to grow Heirloom tomatoes from seeds – A Complete Guide

Today, we are going to brief about “How to Grow Heirloom Tomatoes from Seeds”.


What is an Heirloom Tomato? An heirloom tomato is an open-pollinated or non-hybrid heirloom cultivar of tomato. Heirloom Tomatoes have flavors, colors & textures that are quite different than regular store-bought tomatoes. Heirloom tomatoes are a popular crop for several growers, bringing both a price premium & droves of customers in search of old fashioned tomato flavor. Heirloom tomatoes can be tricky, though, want more labor and producing lower yields than modern tomato varieties. Are Heirloom tomatoes healthier or not? Heirloom tomatoes protect cardiovascular health. They are rich in potassium, which is identified to lower blood pressure as well as folate, which has been shown to help with a lower incidence of heart attacks. Heirloom tomatoes are a good cause of vitamin K necessary for healthy, strong bones.

Soil and sun requirement:

Heirloom tomatoes are not super fussy about what type of soil they are grown in. As with most garden vegetables, they do well in well-drained, fertile loam with a pH level of 5.8 to 7.0. Heirloom tomatoes are non-hybrid tomatoes that reproduce true to form from saved seeds.

Much like other vegetable crops, heirloom tomatoes need nutrient-rich, fast-draining, and loamy soil in which to grow. Adding a 3 to 4-inch-deep layer of compost & mixing it into the top 10 to 12 inches of soil will improve the soil’s texture and drainage while adding nutrients. These warm-season vegetables require full sun, or bright, direct light, for at least 6 to 8 hours per day. Orienting heirloom tomato rows from north to south will provide the plants with the most possible sun. How much sun do heirloom tomatoes need? For healthy growth, heirloom tomato plants require at least 8 hours of direct sunlight a day. However, the hours of sunlight do not want to be consecutive. This means that heirloom tomatoes can be grown successfully in both morning and afternoon sun as long as the number of hours adds up to 8 or more.

Soil Requirement for Heirloom Tomatoes.
Soil Requirement for Heirloom Tomatoes.

Temperature requirements:

Heirloom tomato seeds germinate readily in constant temperatures of 68 to 80 degrees Fahrenheit, emerging in six to 14 days. Although heirloom tomatoes will germinate at temperatures as low as 60°F, it takes longer. Starting seeds at home 6 to 8 weeks before the average last spring frost date, or sowing them in the garden after the last frost date once soil temperatures reach 60°F will produce seedlings. A temperature range of 65 to 75°F is best for heirloom tomato plant growth. When temperatures fall below this range, expansion slows. Heirloom tomatoes will grow in temperatures warmer than 75°F but need to water more often to prevent wilting.

Temparature Requirement for Heirloom Tomatoes.
Temperature Requirement for Heirloom Tomatoes.

Site selection and preparation

Choose a site for heirloom tomato production with well-drained soil that warms up quickly in the spring. Heirloom tomatoes are quite cold-sensitive, so low-lying fields that are subject to late frosts should be avoided. Locate heirloom tomato fields where plants will not be damaged by herbicide drift from neighboring fields. Healthy soil is a key to successful heirloom tomato production. Soil fertility can be enhanced by proper amounts of fertilizers, including properly aged animal manure & green manure. High levels of nitrogen in soils planted to heirloom tomatoes can result in excess foliage at the cost of fruit production. Tomatoes require moderate to high levels of phosphorus, potassium & calcium in balanced proportions.

Water and Fertilizer requirements:

Heirloom tomatoes need consistent moisture to produce even growth and ripe, juicy fruits. Water the heirloom tomatoes when the soil dries to a depth of 1 to 2 inches. Maintaining evenly moist soil without it becoming soggy is crucial to healthy growth. Spreading a one-inch deep layer of mulch around the plants will reduce weed growth while maintaining soil moisture. Tomato plants need one tablespoon of ammonium nitrate per plant after they have set fruit. Repeat applications every 4 to 6 weeks after that will promote large fruits and vigorous plants to support the increasing weight.

Growing Heirloom tomatoes in containers:

Make use of a large pot or container with drainage holes in the bottom. Utilize loose, well-draining soil. We propose a good potting mix with added organic matter. Plant one heirloom tomato plant per pot. Put the selected pot in a sunny spot with six to eight hours of full sun a day. Maintain soil moisture. Containers will dry out more quickly than the garden soil, so check daily & provide extra water during a heatwave. Tips for Growing Heirloom Tomato Plants in Containers: Most tomato plants require a container with a depth of 12 to 18 inches at a minimum. A smaller pot can lead to issues such as soil drying out too fast or blossom end rot. Larger containers prevent the soil from drying out too fast through the hot summer. Heirloom tomatoes require 6 to 8 hours of sun each day. Afternoon sun can excess the plant with sunlight that is too hot. Unless you can commit to a morning & evening watering, try to select a spot on your patio that gets ample sunlight earlier in the day. If you know you will require stakes because you chose indeterminate tomato plants, put the stakes in earlier. Containers or large pots dry out much faster than raised beds. Under-watering & over-watering can have detrimental effects. You must always check the soil before water. If it is dry an inch down into the soil, you require water.

Growing Heirloom Tomatoes in Containers.
Growing Heirloom Tomatoes in Containers.

Heirloom seed collection:

Heirloom tomato seeds “breed true,” unlike the seeds of hybridized plants. Both sides of the DNA in an heirloom variety come from a regular stable cultivar. Heirloom tomato varieties are “open pollinating” and cross-pollination is regular without human intervention. What Are Heirloom Seeds? Seeds typically are obtainable as heirlooms or hybrids. Hybrid seeds are formed by crossing two varieties. The purpose is to create vigorously producing plants. Heirloom seeds are very different. They are old-time varieties, open-pollinated in its place of a hybrid. Gardeners save the seeds each year from their plants & hand them down through generations.

Heirloom seeds can be simply collected and normally almost all seeds will maintain to show the traits of the original seed because of this family of tomatoes almost always self-pollinates. Dramatic cross-pollination may happen in the presence of pollinating insects during flowering. Collecting heirloom seed is as easy as picking ripe tomatoes, mashing into a jar till less than half-full, and filling with water. Shaking from time to time and allowing decomposing for 1 to 6 days until the seeds sink to the bottom, then rinsing until the seeds are clean, and drying. This decomposition is beneficial since it discourages the transmission of diseases to the seed; the drying promotes better germination & because the seeds are easier to separate when they are cleaned.

Container Growing Tips for Heirloom Tomatoes:

Growing heirloom tomatoes in a container is a somewhat different experience than planting in the ground. When you grow tomatoes in a pot, you generally need to pay more attention to the water needs of the plant. In hot, dry weather, the container is likely to dry out quickly & need watering daily. At the end of the growing season, it’s best to discard the potting mix & plant instead of saving them for next year, to avoid the spread of disease and pests. Large tomato plants must be staked so that they have support as they grow. Heirloom tomato growing tip: Heirloom tomatoes aren’t essentially organic. Organic means growing plants without the support of synthetic fertilizers, herbicides, etc. Many gardeners choose to grow their tomatoes organically, but not all organic tomatoes are an heirloom, and not all heirloom tomatoes are grown organically.

Read: How To Grow Roma Tomatoes In Pots.

Growing heirloom tomatoes from seeds:

Color variety:  purple, pink, yellow, orange, dark maroon, striped, marbled, and red.

Superior flavor:  sweet, tart, acidic, or just “old fashioned tomato taste”.

Unusual shapes and sizes: pear-shaped, round, or lobed fruit; sizes vary from present to a two-pound whopper.

Longer ripening season: many heirlooms have a long harvest time, unlike some hybrids that were bred for a heavy crop to ripen at the same time for ease of commercial harvest.

How to grow heirloom tomatoes from seeds? Seeds can be started indoors 6 to 8 weeks before the last anticipated frost in a growing area.  Starting seeds directly outdoors will produce, plants but the yield will be limited. Obtain some seed initial mix. The mix must contain peat moss to help retain water during seed germination as the seeds should be kept moist for proper germination.

If you are starting many varieties of tomatoes or other seedlings, you must have a separate starting container for each variety.  We use 1/2 gallon cardboard milk or orange juice containers that are cut down their length with the ends stapled to hold them together. These are an economical means of separating seeds.  Be sure you mark containers with seed type. We use a piece of clear plastic & put a number on it, then have a cross-reference list with the number and variety. In a bowl, bucket, or another container, place some of the starting mix & add water while mixing to moisten the mix.

Fill the trays with one to one and a half inches of the moistened seed starting mix & distribute seeds over the surface.  Cover seeds with ¼ inch of starting mix & gently firm the surface. Check seed trays every 2 to 3 days to make sure they stay moist.  We cover ours with a loose-fitting piece of plastic wrap to assist retain water.  Seeds will usually take 10 to 14 days to germinate (depending upon variety). Once the seeds have sprouted, they will require a light source. We start our seedlings in our basement & use fluorescent grow light which works very well. Starts the seeds on a window sill make sure turn the seeds daily to keep them from bending toward the light. If starting under a grow light, make sure that the grow light is within 6 inches of the seedlings or they will become tall & leggy. Seedlings require 12 to 16 hours of light a day.  An inexpensive timer works well to control develop light time.  If you use develop lights, make sure to keep plants within 6″ of the light or they will become leggy.

Once the seedlings are showing the second set of leaves, it is time to transplant them from the initial tray to individual pots.  We have created that the best pots are plastic as they retain more water.  The peat pots work well if you make sure to stay them moist. Gently loosen the soil in the starting tray & separate individual plants.  Fill the transplant pot loosely with moistened starter mix & use a pencil to make a hole in the starting mix.  Put in the seedling into the hole up to the second set of leaves. This may need the slight twisting or bunching up of the plant’s root as they can get pretty long.

Gently firm the soil around the seedling & moisten once you have finished transplanting. If you start your seeds very early, you may require to transplant some of your biggest plants again as they will outgrow their pots. Why Heirloom Tomatoes Taste Better? Most plants have the potential to be chosen heirloom. This is loosely defined as those plants grown by generations of gardeners, whose saved seeds generate plants with consistent traits. But heirloom tomatoes offer an intense flavor that set them in a class of their own. Time to grow heirloom tomatoes: Heirloom tomatoes have not been crossbred, and their seeds produce plants that closely resemble the parent plant. Normally ready to pick later than hybrid tomatoes, varieties such as ‘Brandywine,’ which produces large, juicy, pink fruit, can take as long as 100 days to harvest.

Read Lemon Tree Grafting Methods.

Can you save the Heirloom tomato seeds?

Heirloom Tomato Seeds.
Heirloom Tomato Seeds.

Yes.  But you need to take some precautions to prevent cross-pollination from other tomato varieties nearby or the seeds may not generate the tomato you wanted. If you grow more than one variety of tomato, they must be planted at least 20-25 feet apart.  In addition, a tall barrier crop, or a continuous pollen-producing crop must be planted between varieties to distract the bees.  These precautions will prevent most winds caused cross-pollination & cause bees to visit one tomato variety at a time before returning to the hive to clean off their collected pollen.

Saving tomato seed from healthy plants with the best fruit quality. Pick the fruit when ripe, scoop out seeds & pulp into a bowl with a little water, then leave to ferment for 4 days. Separate out the seed from the pulp, rinse the seeds, and then dry them on paper towels or a screen in a warm, dry place with good air circulation. After 5 to 7 days, place seeds in airtight containers & store indoors in a dark, cool, dry place. If properly stored, seeds must remain viable for 3-5 years. Do I need a greenhouse to develop heirloom tomatoes? You can start growing outside as long as your soil is suitable & fertile. Most tomato growers prefer growing in a greenhouse or hoop house, as the growing season is extended because of the warmer rising environment. Also, pests & diseases are much easier to control. With a high-value crop like heirloom tomatoes, many growers are able to pay for their hoop house. Why are Heirloom tomatoes so expensive? Heirloom tomatoes are so expensive because they are not mass-produced. With fewer available, their price normally stays high. Heirlooms are not disease resistant, their vines produce less per acre than hybrid varieties & they do not travel well.

Washing seeds:

When heirloom tomato seed is processed on a large commercial scale, the seed is washed in a shaker washer or flume. In a small-scale seed production where the seed is fermented in containers such as buckets, the first step in washing is to stir the fermented mash, let it settle, and then scoop off much of the pulp balanced on top. Next, water is poured into the mash so that the volume is roughly doubled. If you don’t add enough water, the specific gravity of the mash may be too high to permit some of the good seeds to sink. Adding water quantity lowers the specific gravity. This clarifies the liquid so that you can see the seed more easily. After the water has been added, the mix is allowed to resolve again. The good tomato seeds will sink to the bottom. After the mix has settled, the container is tilted and the pulp & other debris are poured off the top. The pouring process continues until most of the mash is poured off. Lighter, low-density tomato seeds of poor quality can be poured off with the liquid. This washing method is repeated until the water turns clear. Normally it takes anywhere from three to six washings.

When the water comes clear, the contents are then poured into a big strainer. Excess water is expressed by pressing on the seeds with a large spoon, while the tomato seeds are in the strainer. Next, the strainer is turned over upside down over a cloth towel. The seeds fall out into a pile, and the pile is then spread & flattened with a large spoon until the patty is no thicker than ¼ inch. The towel itself is generally spread over a screen so that air can reach the patty from the bottom as well as the top. The purpose of the towel is to wick water away as speedily as possible. The patty of seeds doesn’t need to be turned or stirred present there is a steady stream of air flowing over the seeds. Drying tomato seed: Once the seed has been washed & made ready for drying, it should be dried as quickly as possible without heat. A fan is helpful for this purpose. If the seed is not dried quickly it can sprout or temperature of less than 90°F or 32°C. Once the temperature reaches 95°F damage to the seed can happen. For this reason, the seed must not be dried in the sun when the air temperature is much over 80°F (27°C). Tomato seed is best dried in an air-conditioned room with air circulated by fans.


The curing process is a continuation of the drying process. After the seed has been dried set it aside in a dry environment with good air circulation to cure for 2 to 4 weeks. During this time the moisture content of the seed is slowly reduced. The seed must be thoroughly cured before being placed in an airtight container. If curing outdoors, make sure that mice cannot obtain into the seed.


It is usually not necessary to mill seed after washing & drying since there will be little foreign material with the seed. It can be helpful to screen the seed for size in order to discard small seeds.

Best heirloom tomato plants:

Brandywine: One of the best heirloom tomatoes to consider is the Brandywine. Gardeners love it for the unique flavor & size.

Stupice: Stupice heirloom tomato originates in Czechoslovakia. While the flavor isn’t particularly outstanding, Stupice tomatoes are one of the earliest yielding plants. When you live in a cooler region, you want to extend your growing period as long as possible. Those who live in the northern climates benefit from these heirloom tomato plants, particularly if you grow them in containers.

Even though they are an indeterminate tomato plant, they are compact, so you won’t normally need to stake them. Stupice produces fruits that are 2 inches in diameter, with a long growing season. The plant will generate hundreds of these small fruits.

Silvery Fir Tree: Some gardeners like to develop plants that are ornamental as well. Silvery Fir Tree develops well in containers because they are compact in nature. You won’t want to stake these plants because they rarely become taller than 24 inches.

They differ from other normal tomato plants because of their feathery, silvery gray-green foliage. The silver fir tree fruits are round, contrasting with their beautifully colored leaves. The fruits measure 3 to 3 ½ inches in diameter, weighing five to six ounces. Silvery Fir Tree tomato plants are a determinate variety, producing delicious fruits close to 2 months after planting.

Japanese Black Trifele: If the flavor is the main goal when selecting the heirloom tomato plants, the Japanese Black Trifele is a plant may need to grow. While these fruits aren’t as large as Brandywine tomatoes, they are pear-shaped, turning a wonderful mahogany color as they start to ripen. They usually weigh 3 to 5 ounces.

Manitoba: These Manitoba tomatoes are a hearty tomato, developed for gardeners in Canada. Because the seasons are shorter there, you can expect Manitoba plants to generate earlier in the season than usual. On average, the maturity time is 63 days, depending on the weather & temperature. They reach a general height of three feet tall. The Manitoba tree fruits aren’t as large as Brandywine, but they make an excellent slicing tomato.

Heirloom tomato yield:

Heirloom tomato plants offer yields for a total of 210 to 240 days a year; each plant produces 4 to 5 kg over the period. One acre can accommodate 5,700 to 6,000 plants. The tomatoes have a shelf life of 8 to 10 days.

Read Growing Lettuce In Containers.


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