Glycine max
Origin: Japan
Improvement status: Cultivar
Seeds per packet: ~18
Germination tested 08/2024: 90%
Life cycle: Annual
'Tankuro' is a delicious black soybean from Japan most commonly used for edamame — fresh seeds for steaming are dark green with a slight dark blushing — but it can also make excellent homemade tofu or soymilk. It has a sweeter and richer flavor than typical soybeans. 'Tankuro' has become very popular as a small-scale soybean for home gardeners and small farmers alike due to its high vigor, productivity, and taste. Plants can grow to three feet tall and are absolutely loaded with pods.
EFN collaborator Michael Billington grew this variety for us in 2023 and loved it. Here is what he has to say:
"This soybean was quick to sprout and fast to mature. There was a fair bit of variation in the maturation rate but 80% of the beans seem to mature at about the same time. Approximately 10% matured about a week earlier and 10% matured a week later. There flavor is astounding: buttery and sweet with a touch of tanginess. The orangish hairs that cover the pods seem to carry there own flavor, which I believe is the source of tanginess. When steamed and sprinkled with large grain salt they become delectable snack or sidedish. They even were gobbled up by my daughter.
The plants matured to a height of about 20 inches. I planted them in a double row: there was 6 inches in row spacing and 10 inches separating the the two rows. After an initiatial weeding with a hoe inbetween the two rows they were able to effectively shade out most other weeds. Any weeds that did sprout between the rows were long and spindly and easily pulled by hand. In the future I would do in-row spacing of 10 inches to improve ease of weeding and to encourage more growth to the pods instead of growing a tall stalk that comes from dense planting.
The pods clustered right on the main stalk. This made them easy to harvest by hand. On average, the pods contained three well sized beans, with some having 4 and some having 2. The clusters typically had 5 pods each and about 9 clusters per plant. The clusters formed where the petiole meets the stalk. Each plant averaged about a quart of pods.
When harvesting for fresh eating, it is best to pluck them while the pods are a deep green. If you want to ensure maximum volume while also having full flavor then you can wait until just a few of the leaves begin to yellow. If you wait too long the leaves will almost all be yellow and the pods will just begin yellowing. It is more efficient to cut the whole plant and process the plant on a table. Blanch and freeze immediately. If you are growing for dry beans than you can let the pods yellow on the stalk. Then cut them and lay them on a tarp in the sun and cover them in a large screen. As they dry some of
the pods will shatter and release the seeds. It is essential to have them in direct sunlight for this to work. When fully dry you can remove the screen and lay another tarp over them and then flail the plants through the tarp. I like to snip 18” sections of an old extension cords and duct tape them to a stick to make a good flail that doesn’t damage seeds but still shatters pods. After threshing you can use a rake to lightly rake the stalks to the side. Then you can dump the rest of the material into a clean
drum or garbage can and use a leaf blower to accomplish most of the winnowing."
GROWING TIPS: Direct-sow after all danger of frost has passed. Give plants at least a foot of space in each direction. Protect from small critters like groundhogs who seem to love demolishing soybean plants at almost any stage.
