Black Futsu Squash
Cucurbita moschata
Seeds per pack ~ 20
Packed for 2026
Origins and History of Domestication
Black Futsu is a distinctive Japanese heirloom winter squash belonging to Cucurbita moschata, one of the major domesticated squash species of the Americas. C. moschata originated in the tropical Americas, where Indigenous peoples domesticated and diversified squashes over thousands of years as important food crops alongside maize and beans. The species became especially well adapted to warm, humid environments and today includes butternut-type squashes, tropical pumpkins, calabazas, and numerous traditional landraces.
Black Futsu itself is a Japanese selection rather than an originally Japanese species. Squashes from the Americas reached Europe, Africa, and Asia following the Columbian Exchange beginning in the late 15th and 16th centuries. Cucurbita moschata types were introduced into Asia through expanding Portuguese and other maritime trade networks. Black Futsu is believed to have developed from these introduced squashes through generations of Japanese farmer selection and is generally described as a centuries-old Japanese heirloom. Some accounts associate its cultivation with Japan as early as the 17th century.
Spread and Diversification
Once C. moschata reached Asia, farmers selected plants for local climate adaptation, flavor, storage ability, fruit size, appearance, and culinary usefulness. Over generations this produced an extraordinary diversity of Asian pumpkins and winter squashes. Black Futsu—also encountered under names such as Futsu Black and Futsu Kurokawa—became distinguished by its flattened shape, unusually deep ribbing, dark immature rind, orange flesh, and excellent eating quality.
The variety eventually spread beyond Japan through seed exchanges, specialty growers, and heirloom seed companies. It is now cultivated in North America and Europe as both a gourmet winter squash and an ornamental autumn crop. Its international popularity reflects renewed interest in open-pollinated and culturally distinctive heirloom vegetables. We sourced our Black Futsu Squash seeds from Open Circle Seeds of Potter Valley, California.
Appearance and Characteristics
Black Futsu produces striking, squat, round fruits with pronounced ribs and a somewhat wrinkled or warty surface. Young fruits are typically very dark green—sometimes appearing nearly black—which accounts for the variety's name. As the squash matures and cures, the rind gradually changes through gray-green, buff, ochre, bronze, or chestnut-brown shades and may develop a characteristic blue-gray bloom. Inside is dense, fine-textured golden to brilliant orange flesh.
Individual fruits commonly weigh approximately 2–4 pounds, although growing conditions and individual strains can produce larger specimens. The skin is relatively thin and edible when cooked. Its flesh is particularly valued for a rich, sweet, fruity and nutty flavor that is sometimes compared with chestnuts. Plants are vigorous, warm-season annual vines requiring considerable garden space.
Culinary Uses
Black Futsu is an exceptionally versatile culinary squash. The flesh becomes creamy, sweet, and nutty when roasted, making simple roasting one of the best ways to showcase its flavor. Because its skin is edible, smaller fruits can be sliced into wedges and roasted without peeling. Black Futsu can also be baked, steamed, sautéed, stir-fried, grilled, or fried as tempura. Its flesh works particularly well in soups, curries, stews, purées, gratins, risottos, pasta fillings, breads, pies, and other autumn desserts. Some growers and chefs also use young or mature fruit raw or pickled.
Growing Tips and Vegetation Zones
Black Futsu is a warm-season annual and can be grown in approximately USDA Zones 4–11, provided the growing season supplies enough frost-free warmth for its comparatively long maturation period. In cooler zones, starting plants indoors is particularly useful; in Zones 7–11, direct sowing is practical once the soil has thoroughly warmed. Because USDA zones measure winter cold rather than summer growing conditions, frost-free season length and soil temperature are more important than the zone number for this annual crop.
Plant in full sun, preferably where vines have plenty of room to spread. Fertile, loose, well-drained soil enriched with compost or other organic matter encourages vigorous growth and fruit production. Keep plants consistently watered during vine growth, flowering, and fruit development, while avoiding persistently waterlogged soil. Mulching helps conserve moisture and suppress weeds. Good pollinator activity is essential for fruit set, so insect-excluding row covers should be removed when flowering begins.
Allow substantial room for the vines. Depending on the gardening system, plants may be spaced approximately 24–36 inches apart, with roughly 5–6 feet between rows or hills. The vigorous vines can also be trained onto a strong trellis, although developing fruits may require support.
Sowing Depth
Direct sow Black Futsu approximately ½–1 inch deep, with about 1 inch being an excellent general planting depth. Sow outdoors only after danger of frost has passed and the soil has warmed, ideally to around 70°F (21°C). In short-season climates, start seeds indoors approximately 3 weeks before transplanting, then carefully transplant after frost danger has passed. Squash roots dislike disturbance, so seedlings should be handled gently.
Days to Maturity
Expect approximately 100–110 days to maturity under favorable conditions, although some selections and growing environments may require up to 120–125 days. One seed-library reference lists Black Futsu at 105 days, while another grower lists approximately 110 days. Because it is a heat-loving C. moschata, gardeners in areas with shorter summers should start seeds indoors to ensure adequate time for fruits to mature before autumn frost.
Harvesting Guidance
Harvest Black Futsu when fruits have reached full size, the rind has become hard and resistant to scratching, and the vines and stems begin showing signs of maturity. The fruit's color provides another useful indication: the original dark green-black skin gradually develops mature buff, bronze, brown, or grayish tones. Cut the squash from the vine with pruning shears or a knife rather than pulling or twisting it free, leaving a short section of stem attached. Handle the fruit carefully because bruises and cuts greatly reduce storage life.
After harvest, cure the squash for roughly 10 days to 2–3 weeks in a warm, dry, well-ventilated location. During curing and storage, the striking dark rind commonly changes toward chestnut, buff, or orange-brown. Proper curing improves storage quality and can further develop the squash's characteristic sweetness and nutty flavor. Store sound fruits in a cool, dry, well-ventilated location and inspect periodically for soft spots or decay. Black Futsu is considered an excellent keeper, making it especially valuable as a winter storage squash.
