Japanese Giant Red Mustard leaves on a white background.
Mustard Seeds, Japanese Giant Red
Japanese Giant Red Mustard growing in greenhouse.
Mustard Seeds, Japanese Giant Red
Close-up Japanese Giant Red Mustard leaf.
Japanese Giant Red Mustard leaves on a white background.
Mustard Seeds, Japanese Giant Red
Japanese Giant Red Mustard growing in greenhouse.
Mustard Seeds, Japanese Giant Red
Close-up Japanese Giant Red Mustard leaf.

Mustard Seeds,
Japanese Giant Red

4.8101 ReviewsSKU: #OR107Min. seed count: 200
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Description

(Brassica juncea). Beautiful, large Japanese type. Purple red leaves with a delicious, strong, sharp, almost garlic-like, mustard flavor. Tasty stir fried or boiled & makes a great pickling variety.

Growing Tips: Japanese Giant Red mustard thrives in well-drained, fertile soil with a pH between 6.0 and 7.5. It prefers a sunny spot, 6-12 hours of sun a day, though it can tolerate partial shade, especially in warmer climates. Regular watering is crucial to keep the soil moist, as dry conditions can cause the leaves to develop a bitter taste.

Plant Details

Botanical Name
Brassica juncea
Life Cycle
Annual
Sun Requirement
6–12 hr.
Days to Germinate
5–8
Days to Maturity
40
Planting Depth
¼ in.
Plant Spacing
12 in.
Ideal Temperature
55–70°F
Frost Hardy
Yes

When to Grow

Plant Japanese Giant Red mustard greens during the cool seasons of spring and fall. In regions without killing freezes, they can be grown throughout winter. Sow seeds 4-6 weeks before the last expected freeze in spring, or 4-6 weeks before the first expected freeze in fall. The ideal temperature for Japanese Giant Red mustard is 55-70 degrees F. If you’re not sure how to find your area's first and last frost dates, consult our blog post 'Our Experts Answer Questions, Share Resources.'

How to Sow and Plant

Sow seeds directly into the garden 1/4 inch deep and 2-3 inches apart. For a continuous harvest, sow additional seeds every 3 weeks. If starting indoors, transplant seedlings when they have at least two true leaves. Space plants about 12 inches apart to allow for mature growth​​.

How to Grow

Maintain consistent soil moisture and provide moderate fertilization, particularly nitrogen-rich options to encourage leafy growth. Mulch around plants to retain moisture and suppress weeds. Mustard greens grow quickly and can be harvested as baby greens or allowed to mature for larger leaves. Regular harvesting encourages continued growth.

How to Save Seeds

  • Brassica juncea is capable of self pollinating, but insects can cross pollinate the flowers with other varieties of B. juncea if growing within a 2-mile radius. If saving seeds, isolate the plants from other B. juncea varieties by 2 miles.
  • To save the seeds, allow pods to brown, dry, and become crispy. Shake pods into a paper bag to remove seeds. Store seeds in a cool, dark, dry location.

FAQ

How long does it take for Japanese Giant Red mustard to mature?

Japanese Giant Red mustard matures in about 40 days, depending on the planting season.

Can Japanese Giant Red be grown in containers?

Yes, mustard greens grow well in containers. But make sure that the container is at least 6 inches deep and keep the soil consistently moist.

How often should Japanese Giant Red be watered?

Keep the soil moist. In hot climates, you may need to water twice a day.

What kind of fertilizer is best for Japanese Giant Red?

Use a balanced vegetable fertilizer. High nitrogen levels support leafy growth, while moderate phosphorus and potassium are also beneficial.

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