Seed Saving Made Simple Part I

Once a month, our “Ask a Master Gardener” session is devoted to a discussion about seeds. Our guest this week was Kathy Rothermel, a founding member of the Kingston Area Seed System Initiative (KASSI) and co-owner of Kitchen Table Seeds, an organic seed producer on Wolfe Island.

The simple act of saving seeds carries forward centuries of work by humans to cultivate plants that sustain and inspire us

The Seed Garden: The Art and Practice of Seed Saving. Lee Buttala and Shanyn Siegel, eds.

In our March 12, 2021 blog, we discussed the basics of seeds saving and the importance of open pollinated (OP) seeds, that is, those that are pollinated by insects, birds, wind or other natural means. In OP plants, pollen flows freely between individual plants, maintaining the genetic diversity of the plant population. Over time, these plant populations slowly adapt to local growing conditions and climate. If properly isolated from similar species, OP seeds grow like, or “true”, to the parent plant.


Plant pollination can occur in a number of ways. Some plants contain both male and female parts within the same flower. These are referred to as self-pollinating or “selfers” (e.g. peas, beans, tomatoes and lettuce). Others, such as those in the squash family, are pollinated by insects, and for others it occurs via the wind (e.g. corn).

Isolation Distance, Population Size

When saving seeds, you are trying to keep your seeds “true to type” across many generations of the plant variety you are interested in. To avoid cross pollination of one variety with another, and thus the creation of a hybrid of the two, each variety intended for seed saving should be isolated from others. Each type of plant has its own recommended isolation distance. For example different kinds of lettuce should be isolated from others by 10-20 feet. More information on isolation distances is available at Seed Savers Exchange

Growing leeks for seed. Image credit: Anna Sadura Healey

Seeds can be saved from only one plant to be sown in next year’s garden. However, because each individual plant differs slightly from another, it is ideal to collect seeds from more than one. This maintains the genetic variability of the population. In the home garden, Kathy suggests choosing about 5 robust looking plants, free from disease, obtaining a sampling of seeds from each. Dedicated seed saving operations will harvest from much larger quantities.

Saving Tomato Seeds

Tomato seeds are among the easiest for the home gardener to save. Simply pick a few fruits from each plant (of the same variety) when they have just passed the fully ripe stage.  Select the ones you prefer for appearance since those are the type you will want to propagate. Cut the tomatoes open and squeeze out the seeds, juice and pulp into a clean jar. Leave it for 1-3 days to ferment, stirring once a day.  Covering it lightly with a cloth will help keep the fruit flies out.

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Tomato seeds are encased in a gelatinous covering, which contains germination inhibitors. During fermentation, the gel coating is being consumed by bacteria and yeast in the fruit. Once fermentation is complete pour water into the jar. Stir and allow the mixture to settle. The pulp, mould and non viable seeds will rise to the surface and can be poured off, leaving the useable seeds at the bottom of the jar. Repeat several times until the seeds and the rinse water are clean.

Strain the water and seeds through a sieve and spread them on a a plate or piece of glass to dry for a couple weeks.  Clumps of seeds can be broken up by hand and then stored.


We rarely see lettuce seeds in the garden since this crop is picked and eaten long before it flowers. But if left to do so, just a single plant produces hundreds of flowers, each resulting in 20-25 seeds. Tiny individual florets will eventually mature to look similar to a dandelion head – when this happens, simply cut the stalk and allow it to fully dry. The seed heads can then be gently rubbed by hand to release the seeds.

Lettuce flowers. Image credit: Anna Sadura Healey


Beans are another easy-to-save seed crop. Simply grow your favourite variety and instead of harvesting the entire crop, leave some on each plant to mature and dry to a brown and brittle pod. Remove the beans from the pod, and let them continue to dry for a few more days on a plate or screen. Ensuring the seed is fully dry will avoid later problems with mold.

Beurre de Roquencourt bean seeds. Image credit: Anna Sadura Healey

Storing and Labelling

Most seeds should be stored away from light in a dry location. Glass jars are ideal. There is nothing more frustrating (in the seed saving world at least) than collecting seeds, only to forget come next spring, what exactly is in those jars you have so carefully harvested!  So, be sure to label your jars with the variety, date of collection and source of seed if known.

It is a rewarding experience to become a seed saver, ensuring a supply for both for your own garden and to share with friends and neighbours. Once you have given it a try, and experienced your first successes you may want to explore more detailed information in resources listed below.


Lee Buttala and Shanyn Siegel, eds. The Seed Garden; The Art and Practice of Seed Saving. Decorah IA, Seed Savers Exchange Inc., 2015.

Seed Savers Exchange

Seeds of Diversity Canada