VegetableBean
Tamba Kuro Otsubu Soybean
Tamba Kuro Otsubu is a Japanese heirloom soybean that bridges two culinary worlds: harvest the pods immature for tender edamame, or let them mature for dried beans used in traditional kuromame preparations. This open-pollinated cultivar grows 24 to 36 inches tall in an upright habit, reaching full productivity in 120 to 129 days across hardiness zones 3 through 9. Its cultural significance in Japanese cuisine and reputation as a high-yielding, dual-purpose strain makes it a rewarding addition to any vegetable garden.
Photo © True Leaf Market
Growing Conditions
USDA Zone
3-9
Sunlight
Full Sun
Water
Moderate
Soil
Well-drained, Fertile Loam; Prefers Neutral To Slightly Alkaline
Growth Stats
36 in
Height
TypeUpright
Spacing
8
Plant Profile
Sunlight
Full Sun
Water
Moderate
Zones
3-9
Size
36in H x ?in W
Growth
—
Care
High
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Highlights
This isn't just another soybean. Tamba Kuro Otsubu carries centuries of Japanese culinary tradition in its dark beans, prized equally as a fresh edamame snack and as a dried ingredient for ceremonial dishes. The variety's flexibility means you harvest on your own timeline: pick young pods for sweet, tender eating, or leave them to mature and dry for storage and cooking. Its upright growth habit and moderate water needs fit seamlessly into most garden spaces, from containers to raised beds, while its resistance to bacterial blight, powdery mildew, and other diseases keeps plants thriving.
Common Uses
Tamba Kuro Otsubu serves dual purposes depending on harvest timing. Pick the pods while immature for edamame, the steamed fresh soybean snack enjoyed throughout Asia and increasingly popular in Western cooking. Allow the pods to mature fully and dry for use as kuromame in traditional Japanese New Year dishes, soups, rice preparations, and other cooked applications where the beans' unique flavor shines.
Growing Timeline
No timeline data available yet for this variety.
Care Instructions
Direct Sow
Direct sow seeds in spring after soil temperature reaches 60 to 75°F and all danger of frost has passed. Plant seeds directly into garden soil, containers, or raised beds where they will grow without transplanting.
Harvesting
For edamame, harvest pods when they are full and bright green, typically 60 to 80 days after planting, before the beans inside begin to harden. Gently snap or cut pods from the stem. For dried mature beans, leave pods on the plant until they turn brown and dry, usually 120 to 129 days after planting. Pull entire plants or pick individual pods once fully dried, then shell beans and store them dry. The pods' color shift from green to brown signals readiness for the mature bean harvest.
Growing Calendar
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Companion Planting
Pests & Diseases
Ecology & Traits
Edible
Scientific Classification
Glycine max
Family
Fabaceae
Genus
Glycine
Growth Habit
Upright
Native Status
L48 (I)PR (I)CAN (W)
History & Origin
“Tamba Kuro Otsubu originates from Japan, where it has been cultivated for generations as a culturally significant crop. The variety's name reflects its regional heritage, and it has been preserved as an open-pollinated, non-GMO strain through careful seed saving by both home gardeners and agricultural stewards committed to maintaining Japan's heirloom soybean diversity.”