Seed Saving Tips for the Home Gardener
Seed saving is the art of collecting the seed from your crop and using it in subsequent seasons to grow new plants. Even if you save only small quantities of a few crops, understanding more about the life cycle, breeding tendencies, and botany of your crops will help you manage and care for them more effectively.
Only open pollinated crops will produce seed that is viable and that breeds true to itself. Breeding true means that the plants grown from your collected seed will produce a crop with similar traits (growth habit, disease resistance, taste, etc.) to the parent plant. Even with open pollinated crops, to keep the traits you want, you’ll need to learn about their genetics and how to separate flowering crops by time and distance in the garden.
In general, plants that are grown for their flower, seed, or fruit will be easier to manage as a seed saving crop. If you want to collect seed from crops that are grown for their roots, stems or leaves, the plants must be left in the garden past their typical harvest period so that they can continue to grow, flower, and produce seeds. These crops may triple or quadruple in size by the time a seed crop is produced, so must be given wider spacing in the garden. As they send up flower stalks, support and staking may be necessary to keep them upright to maintain good airflow and minimize pests and diseases.
Seed saving strategies are specific to the species you’re working with, so if you plan to delve deep into the world of seed saving and breeding, we highly recommend picking up a few of the books on the subject. While you’re here, let’s dive a little deeper into the basic concepts of seed saving and plant breeding.
Inbreeding and outbreeding
If you are saving seed with the goal of preserving the varietal traits of your parent plants, you need to understand the reproductive tendencies of the specific crop you are working with. Certain crops have a strong tendency to inbreed. In this context, inbreeding means that the plant pollinates itself (when a single plant has both male and female flowers). This is particularly common in crops with flowers that remain closed during their fertility period. Other crops tend to outbreed, meaning that they share pollen easily with other plants (also referred to as cross-pollination). The plants they share with must be the same species, but can be different individuals and/or varieties. Most crops are not perfectly inbreeding or perfectly outbreeding, but fall somewhere in the middle.
If you want to preserve varietal traits in your saved seed, you need to make sure each crop variety is pollinated by other plants of the same variety. Strongly inbreeding plants are typically easier for a beginner to save seed from since it is relatively easy to make sure the seed breeds true to itself and don’t need much assistance to become adequately pollinated. However, these plants will have less genetic diversity, meaning that the health and quality of the plant is at more risk.
Too much inbreeding can lead to inbreeding depression. This is especially a concern when dealing with the small population size of the home vegetable garden. Just like any other overly bred organism, too much inbreeding can result in low vigor and susceptibility to all sorts of problems. Even in a small sample population, genetic variation is important. Collect seed from a number of different plants (rather than all of the seed from one particular specimen). Even if a few of the plants are smaller or uglier than their neighbors, collecting their seed will help ensure more genetic diversity within the population, making it healthier and more stable over time.
Genetic diversity helps buffer species against decimation by pests and diseases. More variation in the genetic code means it is more likely that some of the species’ offspring will be resistant to varying pests and diseases.
Outbreeding crops will have more genetic diversity, but also are more susceptible to receiving pollen from undesirable plants. For example, if you are growing both broccoli and kale for seed in the same garden, the plants are so closely related (any two vegetables with the same genus and species name will interbreed) that pollen from the kale plant will end up in the flowers of the broccoli if they are flowering at the same time. This may result in a great new variety of brassica, but more often will result in an undesirable cross between the two plants. A reduced level vigor and fitness resulting from this type of cross can be referred to as outbreeding depression. Strongly outbreeding crops need to be isolated from other crops that will cross with them if you want the seed to breed true to its parents.
Isolation
If you wish to maintain consistency and genetic stability in your crop, you will need to isolate it from closely related plants while it is flowering. There are three ways to do this: with space, with time, and with physical barriers. The easiest and most manageable isolation method for the home gardener is to separate similar crops by time.
When properly planned, planting related crops at different points during the season will ensure that they flower and set seeds at different times. This is easiest to accomplish with shorter season crops since you can spread out their planting times without running out of favorable weather.
Longer season crops that are strongly outbreeding will inevitably overlap in the flowering phase may need to be isolated by a large amount of space or physical barriers to reduce the occurrence of cross pollination. These isolation methods can be challenging and even impractical on a home scale, so consider focusing your seed saving attention on strongly inbreeding crops or shorter season crops.
Harvesting dried cilantro seed
Dry Seeded Crops
Most vegetable crop seeds are collected dry. This means that the seed pod is allowed to desiccate (ideally while still on the plant), after which it is collected and stored.
Dry seed collecting is relatively easy. To learn techniques that apply to specific crops, we recommend expanding your library to include a text or two on seed collecting.
Keep an eye on developing seed heads to determine when they are ready for harvest. Depending on the crop, dried seed heads can be a variety of colors (brown, black, white). It is likely that not all of the seed in a planting will be ready at the same time. Collect seeds in multiple passes over a few weeks or collect all at once and cure the unripe seeds separately from the dry seeds. Partially dried seed can be cured if spread out thinly in a warm, dry location. Many seed heads will open up or shatter if left on the plant too long, so keep a watchful eye on the plants as they develop. An impending rain storm may be an incentive to collect seed, so keep an eye on the weather as well as the plants themselves.
Collect the seed. Depending on the crop, size of the seed pod and quantity you are collecting, you can strip seeds from the plant in the field, collect individual seed pods, or pull up entire plants and bring them in for processing.
Process the seed. Totally dry seed can be separated from the seed pods and chaff by hand or by a combination of screening and winnowing. Pouring the collected seeds through a screen will help separate out much of the debris. Lightweight chaff can be separated by winnowing the seed with a standard house fan.
Store the seed. Once seed is totally dry and separated from chaff and pods, find an appropriate container, label it in detail and put it away until it is needed. Seeds can be stored in paper envelopes, which is an especially good choice if you’re concerned that the seed is not fully dried down (they’ll continue to dry in the envelopes). If seed is convincingly dry, plastic containers or bags will help keep it fresh for years.
Wet Seeded Crops
Solanaceous crops and cucurbits are typically collected with wet seeds. These fruits are picked from the plant and the viable seeds must be extracted from the fruit and dried manually.
Leave maturing fruit on the vine as long as possible to allow seeds to develop to full size and increase the rate of seed viability.
Collect fruits and separate seeds from the pulp. Cleaning the seed can take various forms, but rinsing the seeds clean in a sink inside a colander (with small enough holes to retain the seed) is an easy, although time intensive method that works very well. Rinse the seeds under warm water and work off all wet pulp until seeds are clean and separated from debris.
Dry seeds immediately and thoroughly by spreading them out thinly in a warm, dry location.
Where to Start
We recommend starting your seed saving adventure with crops that are easy to separate by time, that are strongly inbreeding so that they require small separation distances, or that you plan to only plant one variety of. It’s even easier to collect seed from plants that you are not concerned about cross breeding.
For the casual flower farmer, collecting seed from annual garden flowers can be super simple and satisfying. Sunflowers, scabiosa, calendula, alyssum, marigolds, salvia, nigella all produce high yields of seeds with virtually no additional effort except to collect the seed pods when they have dried but before they open and drop their bounty.
Here are a few of the easiest crops to save for seed:
[DRY] Lettuce: Lettuce is strongly inbreeding so requires very little separation distance, and has a short growing season so can easily be separated by time as well.
[DRY] Cilantro: most growers will only seed one variety of cilantro in the garden, so cross pollination is not a concern. Additionally, the seed of cilantro is the spice coriander, so you may want to let some of it flower and set seed anyways.
[DRY] Radish: these are some of the fastest growing crops in the garden, so planting multiple successions is very easy to separate varieties by time. They may require some staking to support the seed stalks.
[DRY] Beans: a relatively fast growing crop that is strongly inbreeding. Can be separated by distance even in the home garden and by time.
[DRY] Snap Peas: the ovary of the pea is fertile while the flower remains closed, so the flowers typically fertilize themselves. Allow the pods to over-mature on the vine until they have turned brown.
[WET] Tomatoes: tomatoes are actually somewhat technically difficult to save pure seed from, but they are such a beloved crop that they are often the first vegetable that beginning seed savers take on. You can save viable seed from a planting of mixed open pollinated varieties, but be aware that they will have cross-pollinated each other to some degree. The plants grown from the seed might be very similar to their parent, or they might be very different (maybe you’ll discover a whole new delicious variety). If you want to produce tomato seed that breeds true to its parent variety, you should isolate varieties by at least 25 feet in the garden
Colin McCrate has been growing food organically for over 20 years. He worked on a variety of small farms in the Midwest before moving to the west coast in 2003 to teach garden-based environmental education. He founded the Seattle Urban Farm Company in 2007 with the goal of applying years of horticultural and agricultural expertise to help aspiring growers get projects off the ground or more accurately; in the ground.
He has helped guide hundreds of urban farmers through the design, construction and management of their own edible landscape. Colin is the author of three books; Food Grown Right, In Your Backyard (Mountaineers Books, 2012) and Grow More Food (Storey Publishing, 2022); and is a garden writer for the Seattle Times.