Mustasa (Brassica juncea)

About Mustasa

Mustasa (Brassica juncea), commonly known as mustard greens or Indian mustard, is the fast-growing, peppery leafy green that thrives in Filipino backyard gardens with almost no effort. Among edible crops, few match mustasa's combination of speed, ease, and nutritional density — seeds germinate in 3-5 days, baby leaves are harvestable in under a month, and full-size plants are ready in just 40-50 days. For beginning urban gardeners looking for immediate gratification, mustasa is hard to beat.

The plant forms a rosette of broad, slightly ruffled green leaves that can reach 30-60 cm tall if allowed to grow to full size. The leaves have a characteristic peppery, slightly bitter bite — milder when young and increasingly pungent as they mature. This flavor comes from glucosinolates, the same sulfur-containing compounds found in all cruciferous vegetables (broccoli, cabbage, wasabi) that are extensively studied for their health-promoting properties. The peppery heat intensifies with heat stress and drought, which is why well-watered, partially shaded mustasa grown during the cool season has the mildest, most palatable flavor.

In Filipino cooking, mustasa occupies a position between pechay (milder, sweeter) and kangkong (more neutral) — providing a more assertive green flavor to soups and stir-fries. It is particularly beloved in Visayan and Mindanao cuisine, where it appears in sinigang na baboy (pork sour soup) as the preferred green, in dinengdeng (Ilocano vegetable soup), and sautéed with garlic as a quick everyday side dish.

Beyond fresh greens, Brassica juncea is also the species that produces brown mustard seeds — the same seeds ground into prepared mustard condiment. While Filipino home growers primarily cultivate mustasa for its leaves, allowing a few plants to bolt and set seed provides a free supply of both planting stock and homemade mustard.

History & Discovery

Brassica juncea is believed to have originated as a natural hybrid between Brassica rapa (turnip/pechay ancestor) and Brassica nigra (black mustard) — an event that likely occurred in the overlapping range of these species in Central Asia or the Middle East thousands of years ago. The hybrid proved vigorous and was domesticated independently in multiple centers: India (for oil seeds), China (for leafy greens), and the Middle East (for condiment seed).

Mustard is one of the oldest documented spice crops — references appear in Sanskrit texts dating to around 3000 BCE, and the Bible mentions the mustard seed as the smallest of seeds that grows into the greatest of plants (Matthew 13:31). The English name "mustard" derives from Latin "mustum ardens" (burning must), referring to the practice of mixing ground seeds with grape juice (must) to make the condiment.

In the Philippines, mustasa cultivation likely arrived through multiple channels: Chinese traders and settlers brought the leafy green varieties that integrate into Filipino-Chinese cooking, while Indian Ocean trade networks brought the oilseed and condiment traditions. The Filipino name "mustasa" derives directly from the Spanish "mostaza." Today, mustasa is grown across the Philippine lowlands in home gardens and small commercial farms, with Benguet and other highland areas producing for urban markets.

How to Plant Mustasa in the Philippines

Mustasa is always grown from seed — direct sown into the final growing location. It is one of the simplest vegetable crops to grow, requiring minimal preparation, space, or special care.

Propagation Steps

1. Prepare the growing area: Choose a spot with morning sun and afternoon shade (for hot months) or full sun (for cool season). Prepare moist, rich soil or potting mix. Containers as small as 15-20 cm deep work well. Mix in compost for fertility.
2. Sow seeds directly: Scatter mustasa seeds thinly on the soil surface. Cover with 2-3 mm of fine soil — no deeper, as the tiny seeds need near-surface warmth and light to germinate. Water gently with a fine-rose watering can to avoid washing seeds away.
3. Germination: Seeds germinate rapidly — 3-5 days in Philippine conditions. Keep the soil surface moist during this period. Seedlings emerge as tiny, heart-shaped cotyledons (seed leaves) before producing the first true leaves.
4. Thin seedlings: At 10-14 days (seedlings 5-8 cm tall), thin to 10-15 cm apart for full-size plants or 5-8 cm for baby greens. Use thinnings in cooking — they are perfectly edible and tender.
5. Water and feed: Water daily or every other day to keep soil evenly moist. Apply dilute nitrogen-rich fertilizer (urea, compost tea) every 2 weeks for rapid leaf growth. Mulch to conserve moisture and keep roots cool.
6. Harvest: Baby greens: 25-35 days. Full-size plants: 40-50 days. Cut outer leaves for extended harvest, or pull entire plant. Harvest in the morning for crispest, mildest-flavored leaves. Sow new seeds every 2-3 weeks for continuous supply.

Best Planting Season

Mustasa can be grown year-round in the Philippines — one of its greatest advantages. The cool dry season (November-February) produces the mildest, largest leaves with the least bolting. Hot-season planting (March-May) works with afternoon shade — use 50% shade cloth or position under taller plants. Wet-season planting is viable with good drainage. Succession planting every 2-3 weeks ensures uninterrupted supply regardless of season.

Care Guide

Sunlight

Full sun during the cool season (November-February); partial shade (morning sun, afternoon shade) during hot months (March-May). Mustasa is more heat-tolerant than most brassicas but will bolt rapidly and become excessively bitter in sustained full tropical sun during the hottest months. The balance is 4-6 hours of direct sun — enough for flavor and growth, not so much that it triggers bolting.

Water

Keep soil consistently moist — water daily or every other day. Mustasa grows rapidly and demands consistent moisture for tender, mild-flavored leaves. Drought stress causes toughness, excessive bitterness, and early bolting. Mulching helps maintain even moisture. Container plants dry out faster — check daily during hot weather. Avoid waterlogging, which promotes root rot and stem diseases.

Soil

Rich, well-draining soil with good organic matter content. Mustasa is not fussy about soil type — it grows in anything from sandy loam to clay if drainage is adequate. Optimal pH is 6.0-7.0. Amend with compost at planting. For containers, standard vegetable potting mix works well. Mustasa's shallow root system means deep soil is unnecessary — 15-20 cm is sufficient.

Humidity & Temperature

Mustasa grows best at 18-28°C — the cool season in Philippine lowlands is ideal. It tolerates Philippine heat better than most brassicas, continuing to produce in 30-35°C if given afternoon shade and consistent water. High humidity (70-85%) is tolerated but increases fungal disease risk. The plant has no cold tolerance issues in Philippine lowland conditions.

Fertilizer

Mustasa responds well to nitrogen for rapid leaf growth. Apply complete fertilizer (14-14-14) at planting, then side-dress with urea or ammonium sulfate at 15-20 days. Compost tea applied weekly promotes strong, healthy growth. Avoid over-fertilizing — excessive nitrogen produces fast, watery growth that is more susceptible to pest damage and disease. Organic compost mixed at planting provides a good slow-release nutrient base.

Growing Medium Options

Edible Uses & Nutrition

Mustasa is a versatile leafy green — eaten raw as baby greens in salads, sautéed as a quick side dish, or added to soups and stews where its peppery flavor adds character. It bridges the gap between mild pechay and assertive arugula.

Edible Parts

• Leaves (primary): The broad, peppery leaves — young for salads, mature for cooking
• Stems: Tender stems are edible — chop and cook with leaves
• Seeds: Mature seeds are the brown mustard seed used to make mustard condiment
• Flowers: Edible — small yellow flowers add color and mild mustard flavor to salads

Culinary Uses in Filipino Cooking

• Sinigang na baboy: Mustasa is a preferred leafy green in pork sinigang — added in the last few minutes, the peppery leaves complement the tangy broth beautifully. Particularly popular in Visayan-style sinigang.
• Ginisang mustasa: Sautéed with garlic, onion, and a little oyster sauce or fish sauce — a quick everyday side dish. The heat of sautéing softens the peppery bite.
• Dinengdeng: Ilocano vegetable soup featuring mustasa, bagoong, and other seasonal greens.
• Bulanglang: Mixed vegetable soup — mustasa adds a peppery contrast to milder vegetables.
• Tinola: Some regional variations use mustasa leaves instead of or alongside malunggay or sayote tops.
• Fresh salad: Baby mustasa leaves add a wasabi-like kick to fresh salads — mix with milder greens for balance.
• Pickled mustasa: Chinese-Filipino preparation — mustasa pickled in salt and vinegar, served as a side condiment.

Nutritional Information

Per 100 g of raw mustard greens (USDA FoodData Central):

Mustasa is nutritionally exceptional — among the richest leafy greens in vitamins K (414% DV), A (118% DV), C (78% DV), and folate (47% DV) per 100 g serving. The glucosinolate content (responsible for the peppery flavor) has been extensively studied for cancer-protective properties. Mustasa is also an excellent plant source of calcium (9% DV per 100 g) with high bioavailability. For a crop that grows in under 6 weeks with minimal care, the nutritional return is extraordinary.

Air Quality & Oxygen

As a fast-growing, broad-leaved annual, mustasa provides modest contributions to air quality during its short 6-8 week life cycle. Its primary environmental value lies in its ability to rapidly convert bare soil or empty containers into productive green space. Dense plantings of mustasa create an effective living ground cover that reduces soil erosion and suppresses weeds.

Allowing some plants to flower provides a nectar and pollen source for bees and other pollinators — the small yellow flowers are attractive to beneficial insects that support broader urban garden biodiversity.

Toxicity & Safety

Humans: Mustasa is non-toxic and widely consumed globally. People with thyroid conditions should be aware that raw cruciferous vegetables (including mustasa) contain goitrogens — compounds that can interfere with thyroid function in very large quantities. Cooking significantly reduces goitrogen levels. Normal dietary consumption poses no thyroid risk for healthy individuals. The pungent compounds (allyl isothiocyanate) can cause mild digestive discomfort if consumed in very large raw quantities.

Pets: Mustard greens are not listed as toxic to dogs or cats by the ASPCA. Small amounts are safe for pets. However, large quantities of raw mustard greens may cause gastrointestinal upset in dogs due to the isothiocyanate compounds. The plant is safe to grow around pets.

Common Pests & Diseases in the Philippines

• Flea beetles: Small, jumping beetles that create shot-hole damage in leaves. Most damaging to seedlings. Control with neem oil spray or kaolin clay. Mature plants tolerate moderate flea beetle damage without yield loss.
• Diamond-back moth (Plutella xylostella): The most significant brassica pest in the Philippines. Small green caterpillars feed on leaf undersides, creating "windows" of damaged tissue. Apply Bt (Bacillus thuringiensis) spray — specifically effective against diamond-back moth larvae.
• Aphids: Cluster on young leaves and undersides, causing curling and honeydew buildup. Control with neem oil or strong water spray. Inspect regularly — populations build quickly in warm weather.
• Leaf spot (Alternaria spp.): Brown-black spots on leaves during humid conditions. Remove affected leaves, improve air circulation, and space plants adequately. Rotate away from other brassicas.
• Club root (Plasmodiophora brassicae): Soil-borne pathogen causing swollen, distorted roots and stunted growth. Raise soil pH with lime (club root favors acidic soil). Rotate away from brassica crops for 4+ years. No chemical cure once soil is infested.
• Downy mildew: Yellow patches on upper leaf surfaces with gray-purple mold underneath during cool, humid weather. Improve air circulation and avoid overhead watering.

Frequently Asked Questions

Sources

• Plants of the World Online — Brassica juncea (L.) Czern. Royal Botanic Gardens, Kew.
• USDA FoodData Central — Mustard greens, raw. FDC ID: 169292.
• FNRI-DOST — Philippine Food Composition Tables: Mustasa nutritional data.
• Philippine Statistics Authority — Leafy Vegetable Crops: Volume of Production by Region.
• Halkier, B.A. & Gershenzon, J. (2006). Biology and biochemistry of glucosinolates. Annual Review of Plant Biology, 57, 303-333.
• East-West Seed Philippines — Leafy Vegetable Production Guide.

This guide is for informational purposes. Consult local agricultural extension offices (ATI, DA-RFO) for region-specific growing recommendations.