Saving bean seeds is a lot like harvesting dry beans for eating. In some ways, it can even be easier. You could do it with only one sentence of instruction: Let the beans dry in the pods before harvest. But, to help you get more reliable results, we’re happy to provide the following guidance about how to save bean seeds for planting. And click here to see our other articles on how to save seeds.
On Species of Beans
It’s good to distinguish between the different species of beans and to know the species of the kind(s) you’re growing (but you don’t have to remember what all the other species are). Some things that apply to one species don’t apply to others. The largest portion of beans on the market is what we call common beans, which are in the species Phaseolus vulgaris. These include pole snap beans, bush snap beans, and bush drying beans.
In addition to common beans, Southern Exposure also sells several varieties of lima beans (Phaseolus lunatus), asparagus beans (Vigna unguiculata, also known as yardlong beans), edamame soybeans (Glycine max), fava beans (Vicia faba), one kind of hyacinth bean (Lablab purpureus), and one kind of runner bean (Phaseolus coccineus). Other beans of different species, which as of 2023 are not sold by Southern Exposure, include mung beans (Vigna radiate), adzuki beans (Vigna angularis), garbanzo beans (Cicer arietinum, also called chickpeas), winged beans (Psophocarpus tetragonolobus), tepary beans (Phaseolus acutifolius), and lentils (Lens culinaris). Southern peas, which are in the same species as asparagus beans (Vigna unguiculata), also may be considered a type of bean in some contexts, and the methods of seed-saving described here can also be applied to them. Each binary name (in italics above) indicates a different species. Furthermore, there are many varieties, or types, of beans within each of these species. In some of these bean species, there are literally thousands of varieties. This is an example of how humans are capable not only of decreasing biological diversity but also of increasing it.
All of the beans listed above are in the legume family. On the other hand, some crops, like vanilla beans and castor beans, are not legumes at all, so I don’t consider them to actually be “beans.”
If you plant more than one variety of beans in the same species next to each other, that might result in bean cross-pollination, or it might not. That is, bees might visit the flowers of one variety, and then flowers of another variety, and transfer pollen from one to another, and you might get some beans that are neither fully one type nor fully of the other type. However, beans are not generally prone to crossing, so even if you plant them as close as ten feet apart, you’re unlikely to see crossing. Lima beans are the exception; they can cross with other lima beans at a significant distance, occasionally up to about 500 feet apart. Beans of different species will not cross with each other regardless of how close they are. In some cases, such as when growing seed for sale to a seed company, avoiding cross-pollination is important. Generally, in such cases, you should plan your garden so that different beans of the same species aren’t closer than about 30 feet apart.
When to Harvest Bean Seeds
Snap beans are varieties of beans that have been selected for being harvested and eaten while the seeds are still immature, that is, while the seeds inside the pods are not yet viable. People often refer to them as “green beans,” but snap beans can also be yellow, red, pink, purple, or speckled. In many cases, snap beans are harvested while the seeds inside the pods are barely beginning to form. However, many heirloom varieties of snap beans remain good to eat with their pods, even in the “shelly” stage, that is, even as the seeds fill out the pods and the pods change color with maturity. When preparing beans for eating in the shelly stage, be aware that some varieties’ hulls get tough all the way through, whereas other varieties just get stringier and only need to be strung before or after cooking. Also, be aware that the more mature a bean is when you harvest it, the longer you’ll need to cook it. So, beans harvested in the shelly stage will need to be cooked longer than snap beans harvested at an earlier stage – but not as long as dry beans!
Drying beans, like Pinto Beans, Kidney Beans, and Navy Beans, are varieties that are selected for being harvested and eaten when the seeds have fully matured. Many heirloom varieties are good both when harvested as snap beans and when harvested as dry beans. But, in the 21st century, relatively few gardeners harvest dry beans for eating. Why? I think it’s mostly because, with irrigation, mechanical harvesting, and modern shipping, large-scale bean farmers in dry regions can grow, harvest, and clean huge quantities of dry beans using a small fraction of the labor that small-scale farmers or gardeners in humid areas would use. This results in low prices for the beans you get at the supermarket. So, even if you harvest a lot of delicious, nutritious calories, the time you spend harvesting dry beans for food might not feel worthwhile because it doesn’t save you much money. The beans you harvest at home might be a lot tastier than the ones you get at the supermarket – but that difference might be much more noticeable with other crops that don’t store as well as dry beans.
To harvest any beans for seed or dry beans for eating, let the pods stay on the plants until they’ve gotten dry enough to be leathery or crinkly. The leathery stage overlaps a lot with the shelly stage. At the leathery stage, such as the third bean from the right in the photo above, the shells are fairly thin and flexible, and the beans inside have reached their maximum size. At the crinkly stage, such as the two rightmost beans in the photo above, the shells are very thin and are browner than at earlier stages. The seeds inside are firmer than at earlier stages and may have shrunk some as they continued to dry down after the shelly stage. It’s easier to tell how mature the pods are after any morning dew has evaporated when the pods are likely to be somewhat brittle. So, you might want to harvest your bean seed in the afternoon on a dry day.
If you just want to save seed for yourself, you might just let a few pods get past the snap bean stage.
If you can ensure that the beans you harvest for seed don’t get rained on after reaching the crinkly stage, that will help ensure a good germination rate. If beans that have reached the crinkly stage get wet, they might sprout or get moldy, especially if they stay damp for a long time. If you notice fuzzy mold on any pods or seeds within the pods, don’t keep those because you don’t want the mold to spread to otherwise good seed. However, black speckling, such as you see on some of the pods below, is not a problem.
When and How to Separate the Seeds From the Pods
After you harvest your bean seeds, it’s good to let them cure for a few weeks (usually 2-5 weeks, or until at least a week after the seeds rattle in the pods). It’s best to cure them in a well-ventilated area, and it’s important that they be protected from rain. Letting them cure longer than 5 weeks is usually not a problem, as long as seed-eating bugs such as bean weevils don’t proliferate in them. You can spread them in a single layer on a flat surface to cure or string the pods like beads to hang in your pantry or kitchen. After they’ve cured, thresh them to separate them from their pods. Larger-scale growers thresh using machinery made for threshing, but on a smaller scale, there are several simple, enjoyable methods that you can use. My experience is that children love threshing.
The simplest of the methods is to break each pod open by hand and take the seeds out, as in the photo a few paragraphs above. If you have more than a couple handfuls of pods, this method is also the most time-consuming.
Alternatively, you can fill a pillowcase about halfway with pods, then whack it repeatedly against a table or floor. As long as your floor isn’t as hard as cement, you can whack the pillowcase pretty hard but don’t try to use all your strength. The first time I taught kids how to save bean seeds for planting, I showed them this method, but I didn’t know yet to caution against using all their strength. They had so much enthusiasm for whacking that the pillowcase busted right open!
After a few whacks, it’s helpful to shake the pillowcase so that most of the seeds go to the bottom and the pods rise to the top. Then, you can further crush the pods with your hands or lay the pillowcase sideways so that you can step on the pods without stepping on the seeds that have already been released.
Another method of threshing is to put the pods in a box and stomp on it or dance on it.
Threshing is easiest if the pods have been in a low-humidity environment for the couple of weeks before threshing.
After threshing, you might find that all the seeds have settled to the bottom of your container, and all pod pieces are above them. In this case, it can be easy to just lift most of the pods off of the seeds. However, unless you’ve hand-shelled each pod, you’ll generally need to winnow and/ or screen the seeds to separate them from the pod pieces.
Winnowing works because the pods are much lighter-weight than the seeds. People have been winnowing for many millennia using natural wind; however, we find it much easier to use artificial wind in the form of a box fan because artificial wind is more steady and predictable. Since bean seeds are fairly heavy (relative to most kinds of seeds), the box fan should be on its highest speed. Then pour the seeds and chaff (empty pods, pieces of pods, dust, and any other such debris) in front of the fan and into a container. As you pour, try to make sure the flow of air created by the fan isn’t blocked – not by the container, nor by your body, or by something else. The empty pods and pieces of pods, being much less dense than the seeds, will largely be blown away from the container. With practice, you can get larger and larger portions of the chaff to be separated with each round of winnowing. However, even with practice, it will still take several passes before all of the chaff is removed from the seed.
A barn can be a good place to winnow. The edge of a garage or the door to a greenhouse can also be a good place. Winnowing in your living room is a bad idea because then your living room would be very dusty. Alternatively, it can be challenging to winnow in an open-air space that is unprotected from irregular gusts of natural wind.
Screening separates seed from chaff that’s significantly larger than the seeds are, such as big pieces of pods, or significantly smaller, such as dust. Generally, hardware cloth is a good type of screen to use for separating beans from their chaff, and the three common sizes of hardware cloth are included in the set of screens that we sell. These screen sets come with further instructions about screening.
It’s often best, especially with large seed lots, and especially if you want your seed to be very free of chaff, to alternate screening and winnowing – and sometimes even additional threshing – until all the chaff has been removed.
Storing Bean Seeds
Before storing seeds, it’s good to ensure they’re sufficiently dry. A good test for large seeds such as beans is: to put one seed on a hard floor and tap it with a hammer. If it shatters, its siblings are dry enough. If it squishes, its siblings need to continue to dry down.
When you’re done screening and winnowing, and when the seeds are sufficiently dry, put the seeds in an airtight container so insects can’t get in. Then, we recommend putting the container in the freezer for 5 or more days. This way, you can be sure that no live bugs remain in the seeds. After freezing, store your bean seeds in a cool, dry place, like other seeds. Eventually, bean seeds expire, but they usually last a few years — or longer if kept in a freezer.
How is this different from harvesting dry beans for eating?
You might wonder how all of this is any different from harvesting dry beans for eating. I see two main differences.
First, when people grow beans for harvesting and eating as dry beans, usually they grow varieties that have been selected over the years for their taste, texture, yield, and ease of processing as dry beans. When choosing which varieties to save seed from, you’re more likely to care about their taste, texture, yield, and ease of harvesting in the snap or shelly stage. Drying bean varieties can be a lot easier to thresh and winnow than snap bean varieties.
Second, the purpose of your harvests can make a difference in terms of what you want to be careful about. For example, when harvesting for food, you might be more particular about making sure you get all the chaff out, or about making sure they don’t get mixed with bits of soil, or dust from your floor. When harvesting for seed, you might want to be more particular about the storage conditions, to make sure the seeds don’t die before they are planted.
Saving Bean Seeds for Yourself, for Sale, and for Humanity
There are many ways you can sell bean seeds that you harvest. If you want to sell just a few packets, you might list them on Etsy, Seed Savers Exchange , or Grassroots Seed Network. If you want to sell pounds of seed in bulk, we recommend contacting seed companies before you decide which varieties to plant to make sure you plant a type they’ll want to buy from you.
If you’re going to sell more than a few packets, we recommend doing a germination test first. Beans germinate quickly, so the germination tests are generally pretty easy. However, in our experience, soybeans don’t germinate well in the standard paper-towel-style germination tests. Instead, we test them in potting soil. Other kinds of beans can be tested in paper towels.
Many pole snap beans are endangered. And as I see it, there’s an ongoing shortage of bean seed on the market. Here’s why: Pole beans are generally not well-suited to the scales of agriculture of most of the farmers who are growing seeds for Southern Exposure or for most other seed companies. Making a trellis is a job. Making a few hundred row feet of trellis and then taking it down a few months later is a job that most farmers would rather avoid. The advantages of pole beans – a longer harvest season, not having to stoop to pick them, and a wider range of available types – are generally more appealing to gardeners than farmers. Furthermore, at the scales of larger, mechanized farms, growing pole bean seeds is even less desirable compared to growing bush bean seeds because bush beans can be harvested mechanically, and pole beans cannot.
Each winter, we send a list to the farmers who grow for seed harvests to sell to Southern Exposure. It lists the varieties we’d like to buy seed from the following fall. Each year, most of the crops on the list get paired with people who want to grow them. Each year, most of the pole snap beans on the list remain unmatched with growers.
Sometimes gardeners write to us about a family heirloom vegetable that they have and want to make sure doesn’t disappear. This happens more often with pole snap beans than with any other crop type. When it does happen with a pole snap bean, we are generally not very optimistic about the chances of getting into our catalog, even if it sounds like a tasty and special type of bean. For example, the Suches Yellow Hull beans (pictured in the middle of this article) were given to us by a customer in Suches, Georgia, and have not yet been produced in a large enough quantity for us to sell.
If you’re looking for rare bean varieties, try the Seed Savers Exchange member listings. Their common beans are listed under the category “Beans,” within Vegetables, while their other beans are listed alphabetically under categories such as “Lima Beans” and “Adzuki Beans,” also within Vegetables.
Click here to see all our bean seed listings.
Click here to see our general instructions on how to grow beans.