30 to 40 Days to maturity (warm climates), 50-60 Days to maturity (cold climates). Brassica rapa var. perviridis. Green Boy Komatsuna Mustard Seeds. Cool-season annual hybrid. Komatsuna is an easy-to-grow, mild-tasting mustard variety. Its flavor profile tastes like mild Asian mustard and spinach. It is a cool-season annual hybrid variety known for its cold tolerance, though cold temperatures will slow growth a bit. It can be grown throughout the year in areas with mild temperatures. Try growing in greenhouses or homemade hoop houses during the winter. Approx 11,250 seeds / oz.

Komatsuna Mustard Seeds - Green Boy - Hybrid

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Latin Name: Brassica rapa var. perviridis
Days to Maturity: 30 to 40 Days (warm climates), 50-60 Days (cold climates)
Days to Germination: 5-10 Days
Seeding Depth: 0.5 inches
Plant Width: 4 inches
Row Spacing: 6 inches
Plant Height: 8-18 inches
Growth Habit: Tender leaf, upright growth, loosely bunching.
Soil Preference: Fertile, loamy, moisture retentive soil. The soil should be rich in nitrogen and acidic to neutral in pH (5.6-7.5).
Temperature Preference: 45-90°F
Light Preference: Full Sun.
Pests and Disease: Common pests include harlequin bugs, flea beetles, slugs, and caterpillars. Diseases to be watchful of include downy mildew and leaf blight.
Komatsuna Green Boy Color: Deep green leaves
Komatsuna Green Boy Flavor:Mild spinach-mustard flavor

Other Common Names: Japanese mustard spinach, tendergreen

How to Grow Komatsuna Green Boy

Komatsuna Green Boy Mustard should be grown in fertile well-draining soil. Water frequently, about 1 inch per week. Start in early spring, in late summer for a fall harvest, or in fall for a winter harvest that is protected in a hoop house or greenhouse. If sowing seeds, wait until after the last frost for a spring crop. For best results, start seeds indoors about 2 weeks early and transplant just after the last frost, planting about 8 inches apart. Many prefer to grow this for fall harvesting because of the cold tolerance as it matures. Start at the end of summer or early fall. This mustard grows quickly in warm weather and slows in cooling weather. Plant seeds 0.5 inches deep, about 4 inches apart. Thin to 8 inches apart for full-sized greens. These can also be grown in a hoop house in winter, but keep the average temperature at 45°F or warmer.

Harvesting Komatsuna Green Boy

You can harvest baby greens at 20-25 days and fully mature greens at 35 days if growing in warm weather. The growth will slow in cooler temperatures, taking about 30 days for baby greens and 50-60 days for fully mature greens. If the temperature varies, the growth rate will change. Try and harvest before the first frost, but if not, it’s okay. This plant is cold tolerant down to about 15°F, but it prefers 45°F or warmer if possible though.

For baby greens, start harvesting when the plant is between 6-10 inches tall. For fully mature greens, the plant can reach up to 18 inches in height. Leaves can be harvested individually or cut the whole plant at the base when the desired maturity is reached.

Culinary Tips

Komatsuna Green Boy mustard can be used in place of any dark green. Traditionally, it’s boiled (or steamed) and combined with partially ground sesame seeds and soy sauce. It’s also a great mix with scrambled eggs.

Stories From Our Gardeners

"I have found this to be one of the best mustards for growing in the late fall and even into early winter. It’s great to be able to go into my garden in November and December to harvest some dark greens. I have found that celery and chamomile are also frost resistant and are great companions for any mustard, especially this cold-resistant variety! A few years ago, I had this mustard and some celery growing together in my garden in Southwestern Ohio. We received a surprise freeze on December 1st and I was able to harvest both with no damage. We had fresh dark greens and celery for the end of fall that year!"

- David Wiley, True Leaf Market Writer

Seeds Per Package:

1 g packet - Approximately 405 Seeds
1 oz - Approximately 11,250 Seeds
4 lb - Approximately 45,000 Seeds
1 lb - Approximately 180,000 Seeds

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