Osaka Purple Mustard, Heirloom Seeds

Osaka Purple Mustard, Heirloom Seeds — The Cold-Hardy, Frost-Sweetened Japanese Mustard That Grows Under Snow

Osaka Purple Mustard (Brassica juncea) is the winter mustard green that earns its place in the garden through sheer toughness and beauty. Succulent, tender leaves with sweet stems and a crisp, crunchy texture carry a savory, spicy, peppery flavor when young — growing more pungent at full maturity. Frost doesn't just tolerate Osaka Purple; it improves it — deepening the color and sweetening the flavor. Extremely winter hardy, this variety will grow outside through the winter, even under snow. Highly productive, slow to bolt, and excellent in salad mixes, containers, and microgreens. Baby greens in 20 days, full maturity at 40 days.

Why Grow Osaka Purple Mustard?

• Grows under snow — extremely winter hardy, one of the toughest greens available
• Frost sweetens the flavor and deepens the color — better after cold snaps
• Succulent, tender leaves — sweet stems, crisp and crunchy texture
• Highly productive and slow to bolt — extended harvest season
• Excellent in containers and microgreens — versatile for any growing space
• Open-pollinated heirloom — save seed year after year

Growing Notes

Direct sow outdoors in late summer for fall/winter harvest, or in early spring 4–6 weeks before last frost. Sow seeds ¼ inch deep, 1–2 inches apart. Thin to 6 inches. Full sun to part shade. Water consistently. Harvest leaf by leaf for extended production — do not uproot the whole plant. Color and flavor improve after frost.

Days to maturity: 20 days (baby greens), 40 days (mature)
Packet size: 1.0 g / 500+ seeds
Type: Heirloom, Open-Pollinated, Annual
Spacing: 6 plants per sq ft
Sun: Full sun to part shade
USDA Zones: All U.S. zones