How to Plant, Grow, and Save Seeds from Soybean (Glycine max)
In the US, soybeans are grown as a commodity crop and primarily used for oil and animal feed. However, soybeans are also an excellent crop for home gardeners, who can enjoy them in Asian inspired cuisines or more simply as steamed edamame.
Most gardeners plant soybean seeds directly outdoors. Plant the seeds ½” deep 2-3 inches apart once the danger of frost has passed. Thin to 6” in all directions.
Soybean can suffer from powdery mildew, leaf blight, root rot, and other bacterial, fungal, and viral infections. Deer can also put significant pressure on soybean plants. Protect your beans from pests like deer by using row cover or fencing.
Soybeans can be harvested in the snap/green stage or the dry stage. When soybeans are young and green, they are ready for harvest when the seeds have formed but the pods are still tender. Dry soybeans are ready for harvest when the pods are dry and brittle and the seeds inside are hard.
Eating and Storing
Fresh soybeans can be lightly steamed in their pods and then enjoyed as edamame. Fresh soybeans are also used in soups, stews, stir fries, and in homemade tofu. Fresh soybeans will store for over a week in the refrigerator. Dry soybeans have a shelf life of several years.
Soybean is an annual crop. It will complete its full life cycle, including germination, reproduction, and death, in one growing season.
When saving seeds from soybeans, separate varieties by at least 10-20 feet. You can save seeds from soybean even if you only grow one plant. To maintain a variety over time, save seeds from between 5-10 plants.
It is simple to save soybean seeds. Only save seeds from healthy plants. Harvest the soybean seeds when they are hard and their pods are dry and brittle. If the soybean pods are not completely dry before the first frost, pull the plants up and dry them further indoors.
When the soybean pods are completely dry, break them open to release the seeds. On a small scale, harvested material can be threshed by placing it into a sack, on a tarp, or into a storage container and gently treading on it. The thin coats of soybeans are prone to cracking and the embryos are easily damaged, so be careful when cleaning seeds.
Store soybean seeds in a cool, dark, and dry place and keep them in an airtight container to keep out moisture and humidity. Under these conditions, soybean seeds will remain viable for three to four years.