Red Giant Mustard
A bold, spicy mustard green with large, deep purple-red leaves that add heat and color to salads and stir-fries.
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Meet Red Giant Mustard
A bold, spicy mustard green with large, deep purple-red leaves that add heat and color to salads and stir-fries. Young leaves are milder and excellent in mesclun mixes, while mature leaves pack serious horseradish-like kick. Plants are vigorous growers that tolerate cold weather and light frost, which sweetens the flavor. An excellent dual-purpose plant for both edible gardens and ornamental borders.
When to plant Red Giant Mustard
Direct sow one-quarter inch deep from early spring through fall. Germination takes 4 to 7 days at 50 to 75 degrees Fahrenheit. Thin seedlings to 8 to 12 inches for full-sized plants or grow at 2 to 3 inches for baby greens. For earliest spring crop, start indoors in cell trays 3 to 4 weeks before last frost. Succession sow every 3 to 4 weeks for continuous production.
Your Red Giant Mustard Year
Composed for Zone 7 · typical seasons · frost passes Apr 2, returns Nov 1
Sow Red Giant Mustard Mar – Apr, Aug – Sep, pick May – Jun, Oct – Nov. Set your climate below and every date on this plate re-times itself.
How to grow Red Giant Mustard
Red Giant mustard is a vigorous Asian green producing large, broad, burgundy-purple leaves with a bold, spicy mustard flavor. Direct sow seeds one-quarter inch deep from early spring through fall, spacing 8 to 12 inches apart in rows 18 inches apart. Seeds germinate quickly in 4 to 7 days at 50 to 75 degrees Fahrenheit.
Red Giant mustard grows rapidly and can reach 18 to 24 inches tall in just 45 to 60 days. It prefers cool weather for the mildest flavor and most intense color, but tolerates moderate heat better than many mustard greens. In hot weather, the spicy flavor intensifies significantly.
Succession sow every 3 to 4 weeks for a continuous harvest. For baby greens with milder flavor, harvest at 3 to 4 inches tall. Water consistently for tender leaves and use mulch to keep roots cool. Side-dress with nitrogen-rich fertilizer every 3 weeks for the fastest, most tender growth. The dramatic purple leaves make Red Giant an outstanding ornamental edible plant.
32 plants fit a 4 × 8 ft bed
Each Red Giant Mustard wants 30 cm of elbow room. The planner keeps that spacing for you — every plant, every bed.
Red Giant Mustard's best neighbours
Plant Red Giant mustard alongside other Asian greens and brassicas for a mixed Asian vegetable bed. Lettuce and spinach planted between rows benefit from the light shade of the large leaves. Avoid planting near strawberries. Marigolds and nasturtiums help deter flea beetles. The strong flavor may help repel some garden pests.
Onion belongs beside it. Strawberry doesn't.
Old growers' knowledge, checked against Red Giant Mustard's real companion table below — test any plant you're growing.
Related growing guides
Feed it well
Red Giant mustard grows well in fertile, well-drained soil with a pH between 6.0 and 7.5. Work in 2 inches of compost before sowing. Apply nitrogen-rich fertilizer every 3 weeks for rapid, tender growth. Adequate nitrogen promotes the lushest leaves. Potassium helps develop the deep purple color. Avoid very poor soil which produces tough, excessively spicy leaves.
Ideal Temperature
Hardiness Zone Compatibility
From seed to harvest, stage by stage
Germination
Tiny round seeds germinate rapidly in cool to moderate soil temperatures. Bright green cotyledon leaves emerge within 4-7 days, often showing a faint purple tinge at the stem base even at this early stage. Germination is reliable even in cool conditions as low as 4°C (40°F), though 10-20°C (50-68°F) is optimal.
Seedling Development
The first true leaves appear with serrated edges and begin developing the characteristic purple-red pigmentation. Growth is vigorous in cool weather, and the young leaves are already edible as baby greens with a mild, peppery flavor. The root system establishes quickly in loose, fertile soil.
Rosette Formation
Plants form a broad, open rosette of large, deeply savoyed leaves. The signature deep burgundy-red color intensifies with cooler temperatures and increased sun exposure. Leaves develop prominent crinkled texture with contrasting green to pale midribs. Each leaf can reach 25-40 cm long at maturity.
Mature Harvest
Plants reach full size with leaves up to 45 cm long and intense red-purple coloration. Flavor becomes more robust and spicy as leaves mature. The entire plant can be harvested at this point, or continue picking individual outer leaves. Cool autumn temperatures produce the deepest color and best flavor balance.
Bolting and Flowering
As temperatures rise above 24°C (75°F) or day length increases in late spring, the plant sends up a central flower stalk with clusters of small, bright yellow flowers typical of the Brassica family. Leaf flavor becomes increasingly bitter and pungent once bolting begins. Flowers attract pollinators and can be eaten as an edible garnish.
Seed Production
Flower stalks develop long, slender seed pods (siliques) that dry and turn brown on the plant. Each pod contains 10-20 small, round, dark brown seeds. The seeds are the same mustard seeds used in cooking and condiment preparation. Plants can reach 90-150 cm tall during this final stage.
Sow seeds just 3-6 mm deep — they need some light to trigger germination. Keep soil consistently moist but not waterlogged. Thin to 15-20 cm apart once seedlings have two true leaves.
Caring for Red Giant Mustard month by month
What to do each month for your Red Giant Mustard
July
You are hereRest period for mustard in most gardens — too hot for quality leaf production. Plan autumn sowings which typically produce the best-tasting and most colorful leaves. Clean and prepare beds for late summer planting. Store saved seeds in a cool, dry location.
Know exactly what to do in your garden — every month
One email at the start of each month: what to sow, plant, and tackle right now — for your Red Giant Mustard and everything growing around it. Plus a short starter course that helps you dodge the classic mistakes.
- What to do, right now
- Matched to your season
- Starter course included
Harvesting Red Giant Mustard
For baby greens, harvest Red Giant mustard at 3 to 4 inches tall for the mildest flavor, about 21 to 28 days after sowing. For full-sized leaves, pick outer leaves individually when they reach 8 to 12 inches, or cut the entire plant at the base. Young leaves are best for salads, while mature leaves are preferred for cooking. Flavor becomes spicier in hot weather and as plants age.
assuming you sow when the window opens — set your real date
Pick Red Giant Mustard promptly and the plant keeps producing.
Storage & Preservation
Fresh Red Giant mustard stores for up to 1 week in the refrigerator in a sealed bag with paper towel. For preserving, blanch leaves for 1 minute, squeeze out water, and freeze in portions. Mustard greens can also be fermented Korean-style as a pungent condiment. Dried leaves can be ground and used as a seasoning powder.
What goes wrong — and the fix
Flea Beetles
PestNumerous small round holes peppering the large leaves, most damaging to young seedlings.
Cabbage Worms
PestLarge irregular holes in leaves, green caterpillars visible on leaf surfaces.
Clubroot
DiseaseWilting in warm weather, yellowing leaves, and swollen distorted roots.
Troubleshooting Common Problems
Bolting in hot weather causes intensely bitter, spicy leaves. Flea beetles can damage seedlings heavily before plants are large enough to tolerate the holes. The strong flavor surprises gardeners expecting a mild green. In deep shade, the purple color fades to green. Plants self-seed readily and can become weedy if flowers are allowed to mature.
Growing Tips
- Treat Red Giant Mustard as an autumn-first crop. While it grows in spring, autumn plantings consistently produce deeper color, sweeter flavor, and much slower bolting. Sow 8-10 weeks before your first expected frost for the finest quality leaves.
- Embrace cut-and-come-again harvesting. Never pull the entire plant when you can pick outer leaves and let the center continue producing. A single plant harvested this way will yield greens for 6-8 weeks rather than a one-time harvest.
- Succession sow every 2-3 weeks throughout the cool season. Mustard greens go from seed to baby salad leaves in just 21 days, making it one of the easiest crops to keep in continuous production with minimal planning.
- Control flea beetles, the primary pest, with fine mesh insect netting immediately after sowing. These tiny jumping beetles riddle mustard leaves with small holes and can devastate young seedlings overnight. Prevention is far easier than treatment.
- Water consistently to moderate the spicy heat level. Drought-stressed mustard becomes intensely pungent — sometimes unpleasantly so. Even, consistent moisture produces leaves with a pleasant peppery warmth rather than an aggressive burn.
- Grow as microgreens for the fastest return. Red Giant Mustard microgreens are ready to harvest in just 8-12 days and deliver concentrated flavor with a wasabi-like kick. Simply scatter seeds densely on moist potting mix and harvest with scissors when cotyledons are fully open.
- Use as a living mulch and trap crop among brassica relatives. Red Giant Mustard grows so quickly that it suppresses weeds, and flea beetles often prefer it over slower-growing cabbage and broccoli, protecting your main crop.
- Interplant with lettuce and other mild salad greens for a ready-made mesclun mix straight from the garden. The dramatic red-purple leaves provide both color contrast and a spicy counterpoint to mild butterhead or romaine varieties.
Pick your Red Giant Mustard
Red Giant
The classic large-leaved variety with broad, deep purple leaves and bold spicy mustard flavor.
Osaka Purple
A Japanese variety with rounded purple leaves and milder flavor than Red Giant.
Ruby Streaks
Finely cut, feathery red-purple leaves with a more delicate texture and appearance.
Garnet Giant
An intense deep-red selection with extra-large leaves and strong peppery flavor.
A packet of Red Giant Mustard seeds costs $2-4 and contains 200-500 seeds — enough for an entire season of succession plantings. Organic mustard greens sell for $4-7 per bunch at farmers markets and $3-5 per small clamshell at grocery stores. Growing just a 3-meter row can produce 30-50 harvests of mixed greens over a season, easily saving $60-120 on salad greens alone. As microgreens, the same seeds yield a premium product that retails for $25-50 per kilogram at specialty markets.
Quick recipes
Spicy Mustard Green Stir-Fry with Garlic and Sesame
15 minA quick, high-heat stir-fry that tames the peppery bite of Red Giant Mustard while preserving its vibrant color. The combination of garlic, ginger, and toasted sesame oil transforms the bold greens into an addictive Asian-inspired side dish.
9 ingredientsRed Giant Mustard and White Bean Soup
35 minA hearty, nourishing soup where the peppery greens wilt into a savory broth with creamy white beans. The mustard leaves add a gentle warmth that builds with each spoonful — comfort food with a kick.
9 ingredientsBaby Mustard Greens Salad with Warm Bacon Vinaigrette
15 minYoung Red Giant Mustard leaves are the star of this classic warm salad. The hot bacon vinaigrette slightly wilts the tender greens and mellows their spicy edge, while the smoky-sweet dressing complements the peppery bite perfectly.
8 ingredientsCulinary Uses
Red Giant mustard leaves add bold, spicy flavor and striking color to salads when harvested young. Mature leaves are best cooked by sauteing, braising, or adding to soups and stir-fries, which mellows the intense mustard heat. Use in kimchi and other fermented preparations. Wrap fish or meat in the large leaves for grilling. The peppery flavor pairs with Asian and Southern cuisines.
What's inside
Health Benefits
- Extremely high in vitamin A as beta-carotene — 100g of mustard greens provides over 200% of the daily value, supporting vision health, immune function, and skin cell renewal.
- Outstanding source of vitamin C at 78% of the daily value per 100g, a potent antioxidant that supports immune defense, collagen production, and enhances absorption of non-heme iron from plant foods.
- Rich in glucosinolates that convert to isothiocyanates during digestion — these bioactive compounds have been extensively studied for their ability to support the body's natural detoxification pathways and inhibit cancer cell growth in laboratory studies.
- The anthocyanin pigments responsible for the red-purple leaf color are powerful antioxidants associated with reduced inflammation, improved cardiovascular health, and enhanced cognitive function in epidemiological research.
- Provides exceptional vitamin K levels (over 300% of the daily value per 100g), essential for proper blood clotting, bone mineralization, and calcium regulation throughout the body.
- Contains significant dietary calcium (115mg per 100g) with superior bioavailability compared to spinach, since mustard greens have much lower oxalate levels that would otherwise bind calcium and prevent absorption.
Where Red Giant Mustard comes from
Red Giant Mustard (Brassica juncea var. rugosa) traces its ancestry to the broader species Brassica juncea, which originated through a natural hybridization between Brassica rapa (turnip/field mustard) and Brassica nigra (black mustard) somewhere in the region spanning Central Asia to the Himalayan foothills. Archaeological evidence places mustard cultivation in the Indus Valley civilization as early as 3000 BCE, making it one of the oldest spice and vegetable crops known to humanity. From its Central Asian origins, mustard spread eastward into China, where records of its cultivation for both greens and seeds date back over 5,000 years.
The large-leaved, rugosa varieties — the group that includes Red Giant Mustard — were primarily developed in East and Southeast Asia, where mustard greens became a fundamental ingredient in Chinese, Japanese, Korean, and Vietnamese cuisines. In China, different regional varieties of leaf mustard evolved for pickling (zha cai), stir-frying, and soup making. Japanese takana mustard and Korean gat (mustard leaf kimchi) represent centuries of selective breeding for specific culinary purposes. The Red Giant variety specifically was developed in Japan, where it was valued both as an ornamental garden plant and as a culinary green with its dramatic purple-red foliage.
Red Giant Mustard arrived in Western gardens primarily through seed exchanges and Asian immigrant communities in the 20th century, gaining popularity first among adventurous home gardeners and later in the farm-to-table restaurant movement. Its combination of striking visual appeal, bold flavor, and extreme ease of cultivation made it a favorite of chefs and market gardeners. Today, Red Giant Mustard is grown worldwide as a cool-season crop, prized equally for baby salad mixes, mature cooking greens, and microgreen production. It remains one of the most accessible entry points into growing Asian greens for gardeners of all experience levels.
Red Giant Mustard: did you know?
Fascinating facts about Red Giant Mustard
Red Giant Mustard belongs to the species Brassica juncea, the same plant that gives us brown mustard seeds, mustard oil, and the yellow mustard condiment on your hot dog — the leaves, seeds, and oil are all different products of this incredibly versatile crop.
Red Giant Mustard questions, answered
When should I plant Red Giant Mustard?
What are good companion plants for Red Giant Mustard?
What hardiness zones can Red Giant Mustard grow in?
How much sun does Red Giant Mustard need?
How far apart should I space Red Giant Mustard?
What pests and diseases affect Red Giant Mustard?
How do I store Red Giant Mustard after harvest?
What are the best Red Giant Mustard varieties to grow?
What soil does Red Giant Mustard need?
Why are my Red Giant Mustard leaves green instead of red-purple?
How do I prevent Red Giant Mustard from bolting so quickly?
Is Red Giant Mustard too spicy to eat raw in salads?
Can Red Giant Mustard survive frost and winter conditions?
How do I save seeds from Red Giant Mustard?
What is the best way to cook Red Giant Mustard to reduce the bitterness?
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Set your location once. Get sow, feed and harvest dates built around your real last-frost date and live forecast — no more guessing from a generic seed packet.
From the “When to plant” sectionDrag-and-drop bed planner
Design beds on a grid. Every plant snaps to its proper spacing, and you can see your whole season laid out before you spend a cent on seed.
From the “Growing guide” sectionCompanion conflicts, caught early
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From the “Companions” sectionReminders you'll actually act on
“Water the beans.” “Pick today before it turns.” Timely, specific, and tied to the plants you're really growing.
From the “Harvest” sectionSuccession, scheduled
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From the “When to plant” sectionA record that gets smarter
Every harvest you log teaches it your garden. Next year's plan starts from what actually worked in your soil, not a textbook's.
From the “Overview” sectionPlant these alongside Red Giant Mustard
More Leafy Greens
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