Mustard greens
Brassica juncea
Also known as: Brown mustard, Indian mustard, Sarson, Gai choy, Leaf mustard
Quick facts
- Category
- leafy greens
- Difficulty
- beginner
- Days to harvest
- 30 to 45 days
- Harvest type
- cut leaves, plant regrows for repeated harvests
- Spacing
- 20 cm between plants
Environment
- Temperature
- 10–22°C
- pH
- 6 to 7.5
- EC (hydroponic)
- 1.2 to 2.4 mS/cm
- Daily light
- 12 to 17 mol/m²/day
Climate and zones
- USDA zones
- 5 to 10 (winter low around -29°C or warmer)
- Frost tolerance
- frost hardy (handles regular frost)
- Season
- cool (spring and fall crops)
Viable growing environments:
- outdoor year-round (in zone)
- outdoor in growing season (annual)
- unheated greenhouse / hoop house
- heated greenhouse
- indoor (heated home)
- indoor hydroponics under grow lights
USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.
Growing systems
Mustard greens works in:
- deep water culture (rafts)
- NFT channels
- media bed (ebb and flow)
- wicking bed
- soil bed
Growing media
The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (mustard greens works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Net pot, no medium (Bare-root) | - | - | - |
| Soil-based mix (Potting soil) | varies by source | high | high |
Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.
Nutrient demand by stage
NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.
| Stage | N | P | K | EC target (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.6 |
| vegetative | 3 | 1 | 2 | 1.6 |
Companion-growing notes
- Heavy uptake of nitrogen. Co-grown crops with the same demand will end up deficient even at "correct" EC. Plan around this in shared reservoirs.
Aquaponics suitability
Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
A fast, productive hydroponic green for cool to moderate conditions. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 12–24°C (cool-season; heat above 26°C makes the greens unpleasantly bitter and pungent). Moderate light (DLI 12-18 mol/m2/day). NFT, DWC, raft, or media bed systems. From seed to baby leaf: 3-4 weeks. Full-sized: 5-7 weeks. Cut-and-come-again harvesting works well: take outer leaves while the center continues producing. The peppery heat is milder in baby leaves (useful for salad mixes) and stronger in mature leaves (better for cooking). Red and purple varieties ('Red Giant', 'Ruby Streaks') add dramatic color to salad blends. Succession plant every 2-3 weeks. Flea beetles are the most common pest. For commercial hydroponic salad mix producers, mustard greens add the spicy element that differentiates a premium mix from bland baby spinach.
Plan a setup with Mustard greens
Verified against: rhs-uk. Last reviewed 2026-05-15.