Ask The Gardener: How To Save and Start Tomato Seeds

Yellow Pear Tomato
Yellow Pear Tomato

The tomato (lycopersicon esculentum, annual) is one of the most beloved garden vegetables. This member of the nightshade family is thought to have originated from Peru and has been in the European food source at least since 1595 where it begins appears in written works. However, the tomato did not arrive in North America (in the United States) among home gardeners until the 1700s. For most people think of the tomato is a vegetable, this is a largely culinary and trade definition because tomato genetically is truly genetically a fruit.

Frankly, most home gardeners really don’t care. The tomato adds much color and variety to our lives, both in the garden and on our tables. The tomato is frequently used in relish, soups and stews, sandwiches, and salads.  Our of the tomato in so many things on our table may explain, why it is so beloved among home gardeners.

Non-hybrid Tomatoes

First, you already know you want to save the seed; so, you will want to start with a regionally hearty, non-hybrid, tomato.  Possibly, even an heirloom variety, which your family may have grown up using.

From which tomato should you save the seeds

Tomato Seeds
Tomato Seeds

When choosing the tomato from which to save your seeds you should first consider the plant. Seeds should be taken from your strongest healthiest plant. The reason for this is the strongest health is plant should produce the strongest healthiest progeny.

From this healthy plant, you should choose the very ripest, well-formed, undamaged tomatoes. Tomatoes meeting these characteristics will provide the most mature and healthiest seeds.  Please note that the color of the ripest tomato will be dictated by the tomato variety you have chosen. These colors can greatly vary greatly from nearly black purple to shiny red, yellow, green and white stripes, or some other variation of colors.  So, before picking your tomatoes make sure you understand what a ripe tomato for your variety looks like.

Cautions:

  1. You should not use any of the tomato bloom set sprays, as they have hormones in them, and the chemicals to trick the tomato into thinking the fruit has been pollinated, and as a result, may not have any seeds in those tomatoes. If you are concerned about fruit set, when you plants free of moisture from dew or, rain, or sprinkler, you should gently tap the tomato flower to allow them to self-pollinate.  Also, encouraging pollinators in and around your garden will accomplish in a natural way.
  2. Tomatoes are self-pollinating and, generally, do not naturally cross, with some exceptions in areas of sparse vegetation and/or aired condition.  However, if you are growing more than one variety of tomato to you may want to be sure that you achieve variety isolation (not only your plants, also, your but your neighbors), which can be accomplished by:
    • Maintaining the isolation distance between the varieties the USDA recommends 30 feet.
    • Blossom protection with a physical barrier (either flower screening or plant screening)
    • Growing plants in staggered plantings, so that no two varieties are blooming at the same time.

How to save tomato seeds

Choose fully ripened fruit, gently slice the tomato, scoop liquid pulp and seeds out into a container, and add a small quantity of filtered/dechlorinated water.  Leave the container unsealed, at room temperature, and mix the content the mixture two or three times a day for five to days. The while fermentation occurs and the seeds should settle bottom. Over a fine screen, to catch any escaping seeds, Pour off the liquid, rinse the seeds and spread out to dry at room temperature ( 68 – 75 degrees Fahrenheit).  Use of an elevated fine mess screen is recommended (inexpensively obtained at the hardware or home supply store).  I usually just buy a small window screen and set it on some block or small bricks. However, I have used newspapers and/or paper towels laid on top of the paper plate, in a pinch.

How to plant tomatoes seeds

There are two primary ways to plant tomatoes; direct sow and transplant.

Direct sewing: involves directly planning your tomatoes in the ground there are two approaches for sewing tomato seeds. The first is to plant seeds that have been saved or purchase directly in the soil and the second is planting mature fruit of the tomato.

Using the first direct sow method, which will apply either for purchase seed or for safe seed, you would want to plant in the prepared ground, ¼ inch deep, approximately 6 to 14 days prior to your last frost date.  Use of dark mulches and protective covers is recommended to increase ground temperatures and to protect seedling sprouts until after the frost date.

In mild climates, you may want to use a second direct sow method.  I have used this method in mild coastal climate, such as the coast of Oregon, I’ve used it in Virginia, and in Texas to much success. This method basically involves having a prepared bed where I have marked the placement of my plants for the next year. Selecting the fruit from which I want to reseed, I chop the fruit into sections usually have is for small fruit quarters for larger fruit I placed them in my prepared locations cover them with the light quantity of soil and let them overwinter.  Usually, when the weather is warm enough, the plans will sprout for themselves. One note, you may want to guard this area a small fence, if you have pets (e.g. dogs, cats, squirrels, or other critters domesticated or not), which may want to dig in your garden patch.

Tomato Seedlings In Newspaper Pots
Tomato Seedlings In Newspaper Pots

Transplantation, usually, involves planting your seeds in containers, ¼ inch deep, indoors 6 to 8 weeks prior to your last frost date. The seating area should be a consistent temperature of about 75 to 80°F until the seedlings sprout. Once the seedlings have sprouted a temperature of 68 to 70° is optimal. Here are a few additional recommendations;

  • Plant in a large pot, such as a large cup, and only partially feel the cup perhaps half or three-quarters of the way full, then as the seedlings grow you can gently backfill to the top of the container which will provide a stronger root base for the tomato plant. This will, also, eliminate the need to re-pot your seedlings.
  • Also, to prevent spindly plants, recommend that you place your pots/seedlings near good in direct sunlight source, even, to the point of using reflectors in the room to brighten the space. If the plant begins to lean in one direction, occasionally, rotate your pot. Additionally, supplemental lighting from an electric light source (grow light or fluorescent light), (potentially, more than one from differing directions), is recommended.  Basically, the brighter the sort of light source, within reason, the less likely the plant is to stretch itself out seeking a light source. Use of good indirect sunlight will, also, ease the hardening off process.
  • All transfers started indoors should be hardened off (made used to the outdoor weather and lighting conditions), before they are placed in the garden. To harden off your tomato plants Harden off the plants, tart by placing your plants outside in sunlight for 1 – 2 hours, and then bringing them back indoors. Then add a little more time (45 minutes to an hour, more time may be added, as they progress through the hardening timeline) each day, until they are left outside for an entire day by the end of a week or ten days. Even then it is advisable to provide some partial shade for a few days, by adding shading stakes near the plant to prevent sunburn.
  • When planting your seedling, you should plant it no deeper than the top of the soil within your pot and the plant should be gently secured to and supported with a support stake.
  • Water immediately after planting.

Plant spacing

The plant spacing rules are the same, whether using the direct sow or the transplantation method. Generally speaking, the spacing between plants should be 24-36 inches on center in rows or between plants in garden beds, and in pathways between rows allow 40-48 inches.

Green Tomatoes Tied to a Stake For support
Green Tomatoes Tied to a Stake For support

Plant Support

Select a cage tall enough to support the expected mature size of the tomato plant and with access opening larger than the expected fruit size. Use 4-foot cages for determinate tomato varieties and 6-foot cages for indeterminate and heirloom varieties.

Set the cage over the tomato plant immediately after seedling emergence or seedling transplanting.  Set the bottom ring on the ground and center on the plant.

Drive a  stake into the ground on each side of the cage, which should come to the top of the cage with the bottom of stack driven 8 to 10 inches into the soil to provide stability. Secure each stake to the cage with ties to further anchor the support in place so it doesn’t fall over under the weight of the plant as it grows or strong winds.

As the plant grows, gently, guide branches through the cage openings, which can be carefully secured to the cage, if desired.

Trim the top of each main stem and/ or branches as they grow above the top of the cage.  This will restrain plant height and force the plant to branch laterally.

Cherry Tomatoes
Cherry Tomatoes

Days to maturity

The days to maturity will vary greatly depending upon the variety of tomato planted, weather in your area, the planting method was chosen, available hours of sunlight, the soil moister stability, and soil quality, by should range from about 60 to 90 days from the seedling stage (about 4-5 inches tall).

Soil Requirements

Requires fertile slightly acid soil, in a well-drained location, in the garden. The soil should be worked thoroughly before planting to include a slow release fertilizer (e.g. composted manure and/or compost). Mulch should be applied to the bed and/or rows to within about an inch of the plant base.

Water Requirements

Keep soil consistently moist, but not waterlogged. During hot dry weather, deep watering techniques coupled with supplemental irrigation should be used. However, the water method chosen should not whet the vegetation of the plant. The best results watering should be done during the early morning hours just before day late daylight or within a couple of hours thereafter. This allows more the water to soak in before evaporation begins and keeping the plant dry denies fungus and other diseases a habitat to grow on leaves and fruit.

Fertilizer Requirements

Start by working in plenty of compost and organic matter into the soil before planting. Down to about 24 inches.

When using a commercial fertilizer, chose on high in superphosphate and low in nitrogen is recommended. When adding or side-dressing with nitrogen fertilizer, use calcium nitrate, rather than ammonia or urea forms.

Occasionally, side-dressing with a small quantity Epsom salt is recommended to promote plant health and prevent signs of magnesium deficiency late in the season, when their leaves begin to yellow.

Harvest Tips

I’ll mention it again, begin by knowing what a ripe specimen of your variety of tomato should look like.

As you plant near ripen shield your plants from birds and other animals, which may choose to sample your fruit.

Check your fruit daily and pick all ripe fruit.  This will reduce the opportunity for pests to damage your fruit and reduce loss due to spoilage.  Also, when growing an indeterminate variety, picking them as they mature to encourage new fruit to form.

To harvest tomatoes use a garden scissor or shears and sanitize them between plants (which can be done with a sanitization wipe).  This will lessen the injury to your plant and keep disease and fungi from being passed between plants.

Remove any decayed tomatoes from the plant.

When growing a determinate variety and all fruit has been harvested, remove the plant and add it to your compost pile or otherwise dispose of the plant.  This will, allow you to focus on the remaining plants to be harvested, clear garden space of other things, and remove reduce habitat and/or attractant for unwanted pests and disease.

How to store seeds

Tomato Seed Storage Envelope
Tomato Seed Storage Envelope

To store your seeds, once dry,  a paper envelope is recommended. On the outside of the envelope, preferably before you put the seeds on the inside, I would put the information on the variety of tomato, the year harvested, ‘Open Pollinated’, and determination (if known), and whether or not it is an heirloom variety. If you’ve saved a lot of seats, I would not overfill each envelope.  Once you place the seeds inside the envelope and sealed it; place the labeled envelope inside of a storage container I prefer to use an old cardboard shoe-box, which I have saved for the purpose, and place a label on the outside. If you don’t have a cardboard container to store them in so that they can breathe. Then a good glass or plastic container can serve the purpose. However, I would recommend that you put a small handful of rice inside the container to soak up any excess moisture and humidity and if possible choose a container with a small ventilation hole.  Sometimes these can be found in your local store often as containers to heat your lunch in order to store food for reheating. You will need to place your container in an area that is cool and dry, with even room temperatures,.  Under these conditions,  your seed should be viable (although, you may see some drop in seed germination rates as they age)  approximately 4-5 year. While I have read in some recommendations to store your seeds in the refrigerator, I have never subscribed to that practice.

Some reference materials for growing Tomatoes:

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