Tendergreen Komatsuna is a Japanese mustard spinach that delivers tender, mild leaves in just 35 days, making it one of the fastest greens you can grow. This Brassica rapa cultivar reaches a compact 10 inches tall with a 6-inch spread, fitting easily into small spaces and containers. Frost-tolerant and adaptable to both cool and warm seasons, it thrives in full sun with moderate water and moderately acidic to neutral soil (pH 6.0-7.5). The variety's speed and flavor make it a quiet staple in Japanese home gardens and an increasingly popular discovery for Western growers seeking fast, reliable greens.
Full Sun
Moderate
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10in H x 6in W
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Moderate
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At 35 days to maturity, Tendergreen Komatsuna outpaces most leafy greens, letting you harvest tender leaves before summer heat sets in or squeeze multiple crops into a single season. The plants stay small and tidy, never sprawling, which makes them natural for tight garden beds and containers at 4-inch spacing. Its frost tolerance means you can direct sow in early spring or fall, extending your harvest window on both ends of the season without fussing over seed starting indoors. The catalog artwork hints at the plant's full life cycle: you can let some plants flower and self-sow for a continuous, almost spontaneous second generation.
Tendergreen Komatsuna leaves are eaten cooked or raw, depending on maturity and preference. Young, tender leaves work well in salads or as a mild addition to grain bowls, while slightly more mature plants are excellent in stir-fries, where their mild mustard character adds subtle depth without overpowering. The leaves also cook down beautifully in soups, braises, and side dishes, similar to spinach or bok choy but with a gentler flavor. The entire plant can be harvested as a whole or picked leaf-by-leaf to encourage continued growth.
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You can start Tendergreen Komatsuna indoors 4 to 6 weeks before your last spring frost at temperatures between 55 and 70 degrees Fahrenheit. Sow seeds in moist seed-starting mix and keep them in a bright location; germination typically occurs within 7 to 10 days. However, direct sowing is often more practical and produces equally strong results.
Harden off seedlings over 7 to 10 days by gradually exposing them to outdoor light and wind, then transplant into the garden when soil is workable and air temperatures are stable above 50 degrees Fahrenheit. Space transplants 4 inches apart in rows 10 inches apart. If direct sowing is your choice, you can skip this step entirely.
Direct sow seeds outdoors in early spring as soon as soil can be worked, or in mid to late summer for a fall crop. Scatter seeds where you want them to grow, thin seedlings to 4-inch spacing once they've developed their first true leaves, and water gently to keep the soil consistently moist until plants are established. With frost tolerance on its side, you can sow earlier in spring and later into fall than you might expect.
Tendergreen Komatsuna is ready to harvest at 35 days from sowing, when leaves are tender and mild. Begin harvesting once plants reach 6 to 8 inches tall, either by cutting the entire plant at soil level for a single large harvest or by picking individual outer leaves to encourage continued growth. For the longest harvest window, pick outer leaves regularly and let the center continue growing; this method can extend production by several weeks. The catalog's illustration of plants at all life stages, from young to flowering, suggests you can also let some plants go unpicked to develop flowers and self-sow a second generation without intervention.
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“Komatsuna originates from Japan, where it has been grown for centuries as a beloved cooking green. The name itself, used interchangeably with 'mustard spinach' and 'Japanese spinach,' reflects how deeply this plant is woven into Japanese culinary tradition. Tendergreen appears to be a Western-selected cultivar, bred or chosen specifically for the speed and mild leaf character that appeals to home gardeners. The seed catalog's vintage Japanese stamp and parasol imagery suggest both the plant's historical roots and the romance of preserving and sharing heirloom crops across cultures.”