Curious about how to save your own seeds? Keep checking this page for crop-by-crop guides to get you started saving seeds from your own garden!
Beans and peas have a very similar process when it comes to seed saving, and both are excellent crops for the beginner seed saver to try their hand!
A successful seed crop begins in the planning stage. The first thing to consider before planting seed crops is isolation distance and population size. Let’s take a look at each of these terms.
Isolation distance refers to the distance needed between your seed crop and other plants of the same species of different varieties. For example, the distance between your Cascadia Sugar Snap peas and your Green Arrow Shelling peas, or between your Dragon Tongue bush beans and Fortex pole beans. This distance is important because plants of the same species can cross pollinate. Plants cross-pollinated with a variety different from their own will produce seeds that exhibit a blend of genetic traits from both parent plants, and will not grow true to the original target variety. Intentional crosses can be useful for the purposes of plant breeding, but can diminish the quality of a variety if they occur unintentionally. This is why it’s important to know the specific isolation distance necessary to prevent cross-pollination in a given crop.
You may wonder why isolation distance varies between crops, and the answer has to do with the fascinating ways that different plants are pollinated. Some plants are wind pollinated, others are pollinated by insects picking up pollen and moving it flower to flower. Some plants will pollinate their own flowers, while others need to be pollinated by a neighbouring plant to produce viable seed. Some plants are highly receptive to pollen from neighbouring plants, while others will prefer to self-pollinate and use their own pollen for fertilization even when other pollen is present. It is this huge variability in pollination behaviour that necessitates crop-specific knowledge to prevent cross-pollination.
It’s worth noting that these distances are considered safe, but are not a guarantee, particularly since insects are unpredictable. If you want to further reduce cross-pollination risk, or have a smaller space to work with, you can use other methods to isolate your seed crops. These include barriers such as greenhouses, cold frames and isolation tents, pollinator distraction strips with plenty of flowers to sidetrack pollinating insects in between your seed crops, and isolation in time using succession planting.
Next, let’s talk about minimum population size. The maintenance of a minimum population size ensures that plants have a wide enough genetic pool to maintain the characteristics of the variety and prevent the detriments that come from excessive inbreeding. All modern agricultural crops are inbred in order to isolate the desirable traits that define each species and variety as we know it, however excessive inbreeding within an established variety can weaken the resilience of that seed’s lineage. Careful stewardship of a seed line’s genetics will ensure that the seed continues to perform well, adapt to conditions, pass on its resilience and actually perform better in generations to come.
So, back to beans and peas. Standard guidelines recommend a minimum of 10 feet between beans of different varieties, and 40 feet between peas of different varieties to prevent cross-pollination. This is a fairly small isolation distance as seed crops go. Minimum crop size is 20 plants for both beans and peas. If you are a beginner seed grower with limited space and this number seems out of reach, don’t fret! As a home grower saving seeds for the purpose of learning and for your own use, you can easily save seeds off a small number of plants and grow out the product of your work the next year. BUT, if you plan to grow your seeds for many generations, keep an eye on their vigour and characteristics and consider including purchased seeds of the same variety in your population for a genetic refresh if you notice the quality waning.
Bean and pea seed crops are started and grown much the same as crops for fresh picking. When growing for seed it’s helpful to give plants the longest season possible, so be sure to get your seeds in the ground as early as possible in the spring. Here on southern Vancouver Island that means planting peas as soon as the soil is dry enough to be worked in the spring, and beans around mid to late May, since beans are sensitive to cold during germination and prefer soil temperatures around 15° C for planting.
For the next few months, tend your plants as usual, keeping them watered, weeded and healthy. Now comes the hard part of growing peas and beans for seed. You have to leave the fruit on the plant, resist picking it to eat, and watch it go from delicious and perfectly ripe to tough, dry and overgrown. This is possibly the hardest adjustment as a seed grower, learning to accept beautiful crops going overripe and un-eaten in the field. We promise it’s worth it though, as the satisfaction of growing seed you produced yourself is immensely rewarding!
You’re now going to let your beans and peas get nice and dry in the field. Once the plants start to dry you can stop watering them to help speed the ripening process. It’s best to let beans and peas dry down in the field if possible, however if the plants and pods have begun to dry and rain is coming, you’ll want to pull them in under cover to keep them from being re-wetted and risking mold and premature germination.
When you’re ready to harvest your beans and peas, you can simply pluck off the dry pods, or cut the whole plant. Give the seed pods a squish, if the seeds within are hard, move on the threshing. If not, lay the pods/plants on a tarp in a warm place with good airflow until the seeds cannot be squished at all. This is important to ensure that the seeds withstand the threshing process. If you are only harvesting a small number of seeds, you may find it easier to break open the pods and remove the seeds by hand. If you’re dealing with more seeds or just enjoy a big dusty mess of plants, read on!
Threshing is the first step in seed cleaning and refers to removing the seeds from the plant. Beans and peas are very easy to thresh, you’re simply going to lay them on a tarp with no holes, or in a bin (or a kiddie pool depending on the size of your seed lot!) and shuffle and stomp on the pods until they have all cracked apart, leaving you with a pile of loose seeds and crumbled dry plant bits.
Next, you’ll screen the seeds. This can be done with a screen made for the purpose, or with a makeshift piece of wire mesh with big enough spaces to let the seeds fall through. You will hold the screen over a collecting bin and pour the threshed material onto it, letting the seeds pass through and casting aside the plant material remaining on top of the screen.
The final step in achieving nice clean seeds is winnowing. Winnowing is one of the most ancient forms of seed cleaning and uses only the wind to remove light chaff from a seed lot. To winnow, go outside on a breezy day. Lay down a tarp to collect any seeds that escape during the process. Then, pour your seeds repeatedly from one container to another, pouring at a great enough height that the heavier seeds fall to the container while the lighter chaff is taken by the wind, leaving you with a clean batch of seeds!
The screening and winnowing process will vary between seed batches and is often a process of trial and error and small adjustments to get it right. Don’t be frustrated if it takes some experimentation to get your seeds clean!
Now, simply store your seeds in a cool, dry and dark place until it’s time to plant again in the spring!