This is a continuation of our primer on seed saving. If you did not read it, or need a refresher of the overview, please read part 1.
What to save?
The point of seed saving is to retain the characteristics of a plant you like and carry those genes into the future. You want a vegetable or herbs (or flower) which produces food in the form or leaves or flowers or fruit, grows at a predictable size and rate, thrives in your garden conditions and is disease resistant. This reproducible result is know as growing true-to-type.
For this reason, as mentioned in part 1 of this series, it’s easiest to start by saving seeds from self-pollinators. And it is important to avoid trying to save seeds from F1 hybrids, because seeds from F1 hybrids never breed true to type.
If you believe your isolation distance is pretty good—or you aren’t too concerned about something breeding true — you can save some less promiscuous cross pollinators. Remember that crossing is within a species in almost all cases. (And if the only brassica you have flowering right now is one type of kale, it has nothing to cross with even if you have 10 other brassicas (see below for species detail) nearby. That’s the equivalent of putting those cute little mesh bags over flowers to prevent pollinators from bringing in other pollen.
An example of species in Brassica:
Will cross with
Vates, Scotch curled, Lacinato
Broccoli, cabbage, cauliflower, Brussels sprouts, kohlrabi, collards
Red Russian, True Siberian
Rutabaga, Canola/oilseed rape
What plants I save for seed
- Dry seed from mature pods or umbel
- Cilantro (brown seeds on umbel)
- Dill (brown seeds on umbel)
- Arugula (brassica-like narrow pod) (Cruciferae Eruca)
- Pac Choi (brassica narrow pod) (Brassica rapa)
- Kale (brassica narrow pod) (Brassica oleracea or Brassica napus)
- Lettuce (pappuses like dandelion)
- Mache (biennial; valerian family)
- Swiss Chard (biennial; corky bract ball of seeds)
- Beans (bush, pole, lentils, fava and other broad) (dried pod)
- Peas (dried pod)
- Wet Seed
- Tomatoes (wet seed; fermented)
- Various flowers
- Forget Me Nots (biennial)
What I don’t save for seed
- Anything in the squash family
- Other plants needing good isolation distance
- F1 hybrids
Choosing the plants
Even though it may be tempting to eat the nicest fruit and save seed from the ones you don’t think look as good to eat, that’s the opposite of what you should do. You want to select the best seed from the best of your plants to select for the genetics you most desire in the next generation. You also want the fruit to be as disease-free as possible, since some diseases can be seed-borne.
When to harvest for seed
As a rule-of thumb, you want the fruit of the plant to be fully mature. Dry-type seeds are usually mature when they have fully brown pods, but you want to harvest those before they split open on their own (so you don’t loose seed, have it rained on, or have a garden full of seed for “volunteers” you may not want). Snap beans (bush or pole) and peas are eaten at immature stage; keep these until they reach the dry-bean stage.
Tomatoes are usually picked for eating at an almost-mature stage. For wet-fruiting plants peppers and eggplants, you want really ripe, soft, wrinkled fruit. Eggplants should be yellow and way-beyond edible.
Although I strongly recommend against saving cucumbers and melons and squash, if you save them know that a mature summer squash or cucumber will look like a winter squash—brown, hard skinned. You cannot save the immature seed from these at peak-eating quality.
The flowers listed above would be mature after petal fall with brown, nearly dry seeds.
Getting out the seeds and preparing
It is hard to generalize, as how to remove and prepare the seed depends on the seed type.
Tomatoes and some other fruits (e.g., cucumbers, should you have the isolation distance) do best with fermentation, where fungi and microbes break down the gel coating around seeds. Scoop seeds into a jar and add enough water so they are just covered. Loosely cover jar (to avoid fruitflies) and leave a few days until a white film is present on surface (possibly smelly). Rinse several times until you have clean seeds. Good, viable seeds are denser and will sink to the bottom; poor quality seeds tend to float. Place seeds on a plate for several days to dry. Note that fermentation like this actually kills off disease which could spread from uncured seed into the next-year’s garden.
Other wet seeds, like peppers, can just be scooped out.
Dry seeds can be release be stripping the pods off and shaking seed from pods or rubbing them from umbels. Paper bags are very useful. I find placing seed heads in a bag with the stems sticking out and tying the bundle and hanging several days helps. Ideally you want to free the seeds from their pod without breaking pod into seed-size pieces to make it easier to sort. That said, Southern Exposure Seed Exchange recommends using a pillowcase for beans and to bash it on a wall or the ground to release seeds from the husks.
This is the most tedious task. And your seed does not need to be as clean as commercial seed. However, both soil and pods/chaff/stems/leaves are most likely to harbor insects or fungi which will damage the seeds, so get them as clean as practical. Ideal supplies are strainer or colanders and screens of different mesh (one to catch large debris; one to catch seed and let small debris through. I find using centrifugal force in a pie-pan can gather debris separately from seed.
A fan to winnow light-weight chaff while heavier seeds drop can be useful. Winnowing can be done outside on a dry, breezy day, or inside using a fan to blow away the lighter particle and let the heavier ones drop according to their weight.
A wonderful tour and interview with a favorite seed source—Irena Hollowell of Southern Exposure Seed Exchange—includes several cleaning, storage and packing techniques appropriate for a small scale at home and a little view into the world of seeds: film from 2019 by Josh Sattin is here
Drying seed is critical! You want to get moisture as low as possible. This is crucial if you plan to freeze seed or store in anything non-breathable (plastic bag, tight-closing jar).
Leave trays of seed in very shallow layers on plates, old food containers, or screens in a warm, dry area until fully dry.
The basics: label and store in a cool, dry, dark place.
Paper envelopes which will seal and not leak out your seeds are the best storage container for short-term (1-4 years, depending on plant type). Old pill bottles and similar contains which do not have a tight seal—so they breathe a bit— are also good. Use tight-sealing container only for fully-dry seed.
Long term storage can be accomplished by freezing, in which case you must seal and double-wrap. (For freezing a tight seal is essential and never open the contain while still cold, as room humidity will condense and ruin seed.) The same goes for seeds placed in the lower back of a refrigerator.
(Some perennials require cool and moist stratification; seed like pawpaw can not be allowed to dry out for even a few minutes. These are not covered in this discussion.)
Label envelopes with plant type, variety, date and any other pertinent information. You are nearly guaranteed to forget these details, so write it all down! Store in a cool, dry, dark area like a dehumidified basement.
Excellent reference resource: https://seedalliance.org/wp-content/uploads/2010/04/seed_saving_guide.pdf
A fun, general guide: https://permaculture-exchange.org/wp-content/uploads/2014/02/seedschool.pdf
Books and publications:
How to Guide from the Seed Savers Alliance:
The Seed Garden: A New Seed Saving Guide, Toby Cain, Seed Savers Exchange
The Organic Seed Grower, A Farmer’s Guide to Vegetable Seed Production, by John Navazio