The Japanese word "edamame" is composed of the characters for twig and bean, and it refers to an appetizer made by boiling green soybeans in salty water. Besides being tasty, the dish is high in protein, carbohydrates and fibre and makes a good complement to any meal, or it can be enjoyed by itself as a snack. The plant stands 12 to 30 inches tall and thrives in full sun and humus-laden soil with good drainage. The beans will taste best if you harvest them while they are still young.
Plant edamame in the spring or summer when the soil has reached a temperature of at least 12.8 to 15.6 degrees Celsius. The plant takes 75 to 110 days to mature and is daylight sensitive, so plant in May or June for an early autumn harvest. The traditional planting time in Japan, which has a growing season similar to the northern United States, is when the apple trees have reached full blossom.
Turn the soil with humus and fertiliser rich in potassium and phosphorus. Add nitrogen sparingly, because soybeans are legumes and manufacture their own.
Plant the seeds at a depth of 1 inch, spacing them 2 to 3 inches within rows and spacing the rows 20 to 36 inches apart. Do not pre-soak the seeds. If planting in land that has never previously been used for soybeans, increase the yield by inoculating the seeds so they will be able to produce nitrogen. Inoculant is usually available from the seed supplier.
Protect the growing plants from deer, rabbits and other scavengers by erecting fencing or setting live traps. Thin the seedlings to 3 to 4 inches between plants once they are up.
Harvest the beans when the leaves begin to turn from a bright green to a slightly yellowish-green. The pods should be filled out and still be green or just starting to turn yellow. The pods will last longer if you leave them attached to the branches, but strip off the leaves. You can refrigerate them for seven to 10 days. If you want to keep them longer, boil them for two to three minutes and freeze them.
Extend the harvest by staggering the planting, or plant different varieties that mature at different times.
Scrutinise your seeds carefully if you are wary of GMOs. Many soybean strains are genetically modified to increase yield. Harvest the pods before they turn yellow. Once that happens, the beans are too hard and starchy to enjoy as edamame.