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Edamame: The New Garden-Type Soybean
Quick Link to edamame seed sources
Due to high nutritional value and health benefits, soy foods
are gaining considerable interest in the market place. Much of
this interest has focused on soybean products such as tofu, soy
milk, soy-protein fortified flour, or meat analogs constructed
from extracted soy protein. Interestingly, soybeans are also an
excellent vegetable and may be eaten directly from the pods similar
to other beans or peas. When presented in this
fashion, the soybean is called vegetable soybean or
Edamame is very easy to grow—as easy as growing any bush
bean. It’s planted the same way as bush beans, and a mature
soybean plant (edamame plant) is about 2-feet tall. After the
soil has warmed to 65°F, sow seeds 1 inch deep and 2 or so
inches apart, in rows 15-30" apart. Don’t rush
planting. If the soil isn’t warm enough, the seed will not
germinate. Stagger the planting times
to provide a continuous harvest that will not overburden your
gardening time with picking and storing beans.
The best way to harvest edamame is to manually pick the immature,
green pods. This can be accomplished by hand picking each pod,
or you can cut the plant at the base or pull the whole plant out
of the ground and pick pods by hand. The vegetable (botanically,
it is a fruit that is classified by type as a legume) is ready
to harvest after the seeds have reached full size but before any
pod yellowing begins. Harvesting edamame at the right time is
critical for maximum texture and flavor. If pods are allowed to
turn yellow much of the quality is lost. The quality is best when
the pod is plump and bright green, similar to snow peas in color.
Cooking and Storing Edamame
Boil or steam the pods for 4 to 5 minutes (in lightly salted
water if your taste prefers), cool under running water, and squeeze
the seeds from the pods. Beans are difficult to remove
from pods unless blanched or steamed. The soybeans can be eaten
by themselves as a “finger food” or added to soups,
salads, fried rice, or other dishes. Do not eat the shells, as they
are too fibrous to be edible.
After cooking, the beans can be frozen in or out of the pods
and enjoyed later as an out-of season treat. Store in freezer
(-20 degrees Fahrenheit). The advantage of eating the immature,
green soybeans instead of the ripened, dried seeds is the better
taste, crunchy texture, and appealing green appearance. They taste
good cold or hot, and the attractive bright green color enhances
the appearance of many dishes. Additionally, the young, green
soybeans are more easily digested since the complex carbohydrates
(oligosaccharides) of the mature seeds are not yet formed.
Edamame Varieties Available
Although all soybeans are edible, certain soybean varieties with
larger seeds and milder taste have been developed for human food
usage and are commonly sold in Japan and Korea. These Asian food
varieties have desirable characteristics but are not well adapted
to the climate, insects, and diseases of the United States. Soybean
breeders in the United States have crossed some of these large-seeded
Asian varieties with adapted US grain varieties and developed
varieties that are better adapted vegetable types for
growing in the United States.
The garden type or vegetable soybeans have an optimum harvest
period for green pods of just a few days since all the pods on
a soybean plant tend to develop together. The advantage of growing
several varieties with different maturity dates is longer harvest
periods that are spread out to allow several harvest sessions.
This may also be accomplished by having several planting dates
(estimate 3 days delay in planting for one day delay in harvest
but this will vary widely). Like all soybeans these varieties
are self-pollinating and true-breeding, and therefore you may
let a few plants ripen without picking and use these seeds for
next year’s planting.
Commercial edamame suppliers:
Johnny's Selected Seeds
Vermont Bean Seed Company
University of Illinois: GardenSoy variety samples available
At the University of Illinois, selections have been made from specially bred hybrid populations of large-seeded soybeans and now there are a number of promising vegetable-type soybean lines adapted to Illinois growing conditions.Thirteen varieties, named with the prefix Gardensoy, have been released ranging from early maturing (maturity group 0) to late (group IV). The varieties produce soybeans that range from about 50% more to twice as large as the common grain types of soybean grown in Illinois. The tradeoff is lower yield. These vegetable types yield only about 60 to 80% as well as grain types of soybean and therefore are not competitive for large-scale production or processing. Because of their bigger seed size and better taste they are being offered to home gardeners for small scale production and hand harvest. As harvest machinery and techniques are developed for proper harvest of the vegetable types of soybean, larger scale commercial production may become practical.
The University of Illinois has ongoing research plots of edamame each year. For additional information on research trials and/or sample seed packets that may be available for a small fee, contact Research Specialist Theresa Herman.