Consider trying on-farm seed saving!

Crystal Stewart-Courtens and Natasha Field

As part of our Northeast-SARE funded seed production grant, we have been working with growers to identify which open-pollinated crops they may be able to grow for on-farm use to reduce seed cost and increase seed quality and availability. Open-pollinated varieties are those in which a correctly isolated group of parent plants will produce seed that can be grown true to type the next year. This can include newly created varieties or old favorites, also known as heirlooms. We’re featuring tomatoes, annual brassicas, and lettuce as three easy crops to get started with for seed saving.

Production of Tomato Seed for On-Farm Use

Tomatoes are a great first crop to try for seed production given the cost of seed and ease of seed production. Tomatoes are strong natural inbreeders, meaning they are generally self-pollinating and only require 20-30 plants to maintain the genetics of a variety. Isolation distances of 50 feet are generally adequate for on-farm use of the seed, although commercial production may require isolation distances of 150 to 200 feet in an abundance of caution. We recommend you start with an open-pollinated variety that is a cherry or plum tomato as they produce a lot seed compared to beefsteak heirloom types, which produce less seed. However, if you only want to save a few ounces of seed, any OP tomato you love will work great!

Since seed production requires fully ripe tomatoes, grow the tomatoes as you would for market production. If you have the isolation distance, you can simply harvest a portion of your market production and set it aside for seed.

Tomato seeds require fermentation to dissolve the gel that is around the seed in the fruit. The simplest method for a small amount of seed is to squish the insides of the tomato into a small bucket or large jar. Generally, fermentation takes two to three days at room temperature. Just stir the seed a few times a day to introduce oxygen, and once the seed has mostly fallen to the bottom of the vessel, it’s ready to be rinsed and dried. To rinse the tomato seeds place them in a bucket with extra space then add water to the bucket, let the seed sink to the bottom, pour off the tomato chunks and excess water and repeat until the water is clear and only seeds are left. Dry them on screens with fans, stirring them occasionally to break up chunks.  If dried in a greenhouse or tunnel, make sure that the temperature does not exceed 110F.

Yield can be 1-2 pounds of seed per 100 bed-feet of tomato plants, depending on the variety.

Production of Annual Brassica Seed for On-Farm Use

Annual brassicas like broccoli raab (Brassica rapa), summer red radish (Raphanus sativa) and arugula (Eruca sativa) are great to produce on farm because of the relatively high seed yield you can harvest as well as ease of seed cleaning. The difficulty is that brassicas are out-crossers and some species will readily cross with broccoli, cauliflower, wild mustards and other flowering brassicas if the genus name is Brassica. If the genus name is not Brassica, like radish (Raphanus), it will not cross with those in the Brassica genus. Recommended isolation distances are ½ to 1 mile, but timing of flowering can also be a way to isolate varieties. Since brassicas are out-crossing and will suffer from inbreeding depression or potentially are self-incompatible, 100 plants are the recommended minimum to maintain a variety.

Plant your crop as normal for market production in the spring. Getting to flower and seed production will be 45-60 days after market production depending on the type of brassica. Plants can get up to 7 or 8 feet tall and might require trellising to avoid plants from lodging.  When the plants have pods that are getting brown on most of the plant, clip entire seed stalks and lay them in a room temperature, dry place on tarps to dry more. The pods will shatter when handled, so do this in the morning when the dew will keep the pods from breaking open and dumping seed everywhere.

Once fully dry, place the seed stalks in a bucket or solid bin and stomp or hit the plants to shatter the pods. You can do a winnowing or screening pass if you’d like or use seed as-is. Yield can be 5-10 pounds per 100 bed feet.

 Production of Lettuce Seed for On-Farm Use

Lettuce is another relatively easy seed crop. It is a strong inbreeder, self-pollinating and requiring only around 20 plants to maintain a variety. Often the flowers are pollinated before they open, so a small isolation distance of 10 feet from other flowering lettuces is recommended, and if producing lettuce seed commercially you only need a 20-foot isolation from other lettuces. All lettuce is open-pollinated but some varieties have “Plant Variety Protection” on them and you can’t save seed from them.  Verify that your lettuce is not protected prior to saving seed (this is still rare).

To grow lettuce for seed, start and plant out as you would grow lettuce for market. If you are growing in three rows per bed at 1-foot spacings or less, then harvesting half of the lettuce for market is recommended to leave wider spacing for the flowering plants. Otherwise, 1-foot spacing in row, 18-24 inches between rows is recommended for final spacing without thinning.

When lettuce is market size, it is recommended to check the plants for off-types, which could be varying colors or leaf shapes, and remove them. While we want flowering for seed production, we are always careful to remove early bolting lettuce so that we don’t select for lettuce that will bolt early when we are growing it for a food crop.

Once past market size, the lettuce will easily bolt in the summer heat. Flowering and seed production takes around 45-60 days longer than market production. Plants will grow 3-5 feet tall and may need some kind of simple trellis to keep them upright. When the flowerheads are dry with white flower tops and the seed inside is also dry, cut the whole stalks and lay them on a tarp under in a room temperature, dry location to finish fully drying.

After that, shaking the plants upside down will release most of the mature seed. You can rub the seed heads between your hands to release the seed as well, just wear a mask or respirator to avoid inhaling “the fluff,” which is very irritating to the lungs.

Yield can be from 1 to 3 pounds per 100 plants, and 300,000 – 500,000 seeds per pound, so you can produce plenty of seed for your own use in a small amount of space.

For more information about on-farm seed production, reach out to Crystal at cls263@cornell.edu or 518-775-0018

This material is based upon work supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, through the Northeast Sustainable Agriculture Research and Education program under subaward number LNE22-446

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

Resources

https://www.mofga.org/resources/seeds/lettuce-seed/ Lettuce Seed by Nicolas Lindholm

https://seedalliance.org/wp-content/uploads/2017/04/Lettuce-manual-2011.pdf Lettuce seed production by the Organic Seed Alliance

https://seedalliance.org/publications/tomato-seed-production-guide/ Tomato seed production guide by the Organic Seed Alliance

https://seedalliance.org/wp-content/uploads/2017/04/Radish_Seed_Manual.pdf Radish seed production guide by the Organic Seed Alliance