Basic rules of seed saving:
1. Do everything you can to ensure the plants are healthy. They’re the mothers of your seeds!
2. Collect seeds from early flowers rather than later. The younger plant is less likely to experience mutations that may negatively affect your seed stock. I like to keep seed from the second or third sets of flowers on bean plants.
3. Mark fruit you’re keeping for seed with twist ties or other tools. This is particularly important if you’re using mechanical isolation (see below).
4. Do not keep seeds from malformed fruits or sick plants. Always, you are trying to preserve the ideal.
How to isolate:
Beans are perfect flowers and usually pollinate themselves; therefore, many people do not worry about protecting them from cross-pollination. However, we live in an area with lots of bumblebees who often tear open flowers to reach food. I have had little success maintaining bean purity without some form of isolation. Each of the following forms of isolation has proven successful for me.
Physical: This is the easiest form of isolation. If you’re the only person growing beans on the block, and you grow only one variety of bean, you’ve already isolated your variety so that the seed will be pure.
Mechanical: Since I grow lots of beans at one time, this is the strategy I most frequently use. It’s fiddly, but it works. I gently bag flower stems with organza drawstring bags before the flowers open. If a flower on the blossom spray has already opened, I snap that flower off and cover the rest. This guarantees that whatever beans develop on a flower stem will be isolated from cross-pollination and will have pure seed. Try to collect seed from as many plants of your variety as possible—the more the better to help maintain varietal genetic health. Once the pods have set, remove the bag to allow the pods to grow normally and mark the flower stem with a twist-tie or similar.
Temporal: Use time to help you isolate beans. You might try growing your variety in the fall instead of having it share a yard this spring with another variety. With temporal isolation, your goal is to make sure the variety blooms at a time no other bean nearby is blooming.
Wait until the pods are dry and crackly before removing pods from the vine. After you shuck the seed, let the seed dry further on a plate until they are dry enough to “crack” rather than “smash.” Once seed stock is thoroughly dry, place in a ziplock bag or other airtight container, and freeze for three days to kill any bean seed maggot larvae. After you remove the bag from the freezer, let it defrost completely before unsealing it. This helps keep the moisture balanced so there aren’t extreme shifts in moisture, which greatly limit the seeds’ viability.
I keep all my dry beans in lidded jars in a dark cabinet. Keep them away from shifts in temperature and light. You can also keep your seed beans in the freezer—that helps keep in them viable for longer.
Bush: Low-growing variety with no twining stems.
Cornfield: Pole variety suitable for growing in a cornfield, up corn stalks.
Common: Phaseolus vulgaris, snap and dry beans.
Cutshort: Descriptor for varieties whose seeds are packed so tightly inside the pod that the ends are “cut short.”
Dry: syn. “Eating,” descriptor for beans are grown for their dried seeds, not their green pods.
Greasy: Descriptor for varieties that lack the normal super-short, fine hairs on the pods that make them appear velvety—these pods appear “greasy” because they are naturally hairless.
Half-runner: Medium-height variety that has some twining stems. (This is confusing terminology, as a runner bean is a different species, Phaseolus coccineus, but a half runner is still the same species as a common bean, Phaseolus vulgaris.)
Lima: Phaseolus lunatus, a different species than common bean. Limas grow better in heat than common beans do.
Pole: Tall, twining variety that needs trellises and support.
Runner: Phaseolus coccineus, a different species than common bean that won’t set pods in heat, but does grow beautiful, tall plants with red, white, or orange flowers.
Shelly: A stage between snap and dry when the pods are mostly dry and the seeds inside full-size; remove the beans from the dry pods, and eat them this stage after braising them in butter and stock. Mmmmm.
Snap: syn. “String,” descriptor for varieties grown for their fresh pods. Many dry beans make decent snaps, too.