Red Komatsuna Mustard is a cool-season hybrid that brings striking visual appeal and mild heat to your salad bowl. This Japanese mustard green, scientifically a Brassica rapa var. japonica, produces broad leaves with deep red coloring and prominent red veins that intensify as temperatures drop, making it as beautiful as it is flavorful. Ready to harvest in just 40 to 49 days, it thrives across hardiness zones 2 through 10 and grows as a compact rosette reaching 18 to 24 inches tall. You can harvest baby leaves in as little as 20 to 25 days, or wait for full maturity, and it adapts equally well to containers on a patio or traditional garden beds.
Full Sun
Moderate
2-10
24in H x ?in W
—
Moderate
Hover over chart points for details
The real draw here is how the cold weather transforms this hybrid into a deeper, more vibrant red while sharpening its personality in the kitchen. Unlike its green mizuna cousins with their finely lacerated leaves, Red Komatsuna has broader, less deeply cut foliage that's easier to handle in salads and cooking. It's a vigorous grower that performs exceptionally well in baby leaf production, meaning you can begin harvesting tender young leaves in under a month and keep picking from the same plant throughout the season.
Red Komatsuna shines in fresh salads where its mild pungency adds complexity without overwhelming delicate greens, and its striking red veins make every plate more visually interesting. The tender young leaves work beautifully in Asian stir-fries, soups, and quick sautés, while mature leaves hold their color and structure through cooking. Baby leaf harvests are particularly prized for microgreen trays and high-end salad mixes where appearance and tenderness command attention.
No timeline data available yet for this variety.
Start seeds indoors 4 to 6 weeks before your last frost date in soil kept between 55 and 70 degrees Fahrenheit. Red Komatsuna germinates reliably in this range and produces sturdy seedlings ready for transplanting within 3 to 4 weeks.
Harden off seedlings over 7 to 10 days by gradually exposing them to outdoor conditions, then transplant to the garden once soil can be worked in spring or in late summer for a fall crop. Space transplants 6 inches apart in rows spaced 8 inches apart. This variety's frost tolerance makes it particularly valuable for fall planting, often producing superior color and flavor as temperatures drop.
Direct sow seeds 1/4 inch deep in your garden bed in spring as soon as soil is workable, or in late summer for a fall harvest. Succession planting every 2 to 3 weeks extends your harvest window throughout the season.
Begin harvesting baby leaves as early as 20 to 25 days after sowing by pinching or cutting the outer leaves, allowing the plant to continue producing from the center. For full maturity, wait until 40 to 49 days when the rosette reaches its full size and the red coloring has deepened, particularly after exposure to frost. Harvest in the morning when leaves are crisp and full of moisture. You can cut the entire plant at soil level or continue picking individual outer leaves for an extended harvest window.
Enter your ZIP code to see a personalized growing calendar for this plant.