Vietnamese coriander
Persicaria odorata
Also known as: Rau ram, Vietnamese mint, Cambodian mint
Quick facts
- Category
- herbs soft
- Difficulty
- beginner
- Days to harvest
- 60 to 90 days
- Harvest type
- cut leaves, plant regrows for repeated harvests
- Spacing
- 20 cm between plants
Environment
- Temperature
- 18–32°C
- pH
- 5.8 to 7
- EC (hydroponic)
- 1.2 to 1.8 mS/cm
- Daily light
- 10 to 18 mol/m²/day
Climate and zones
- USDA zones
- 9 to 13 (winter low around -7°C or warmer)
- Frost tolerance
- frost sensitive (dies at first frost)
- Season
- year-round tropical (needs consistent warmth)
Viable growing environments:
- outdoor in growing season (annual)
- 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
Vietnamese coriander 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 (vietnamese coriander 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 | 0.8 |
| vegetative | 3 | 1 | 2 | 1.5 |
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
An easy, productive herb for warm, moist hydroponic systems. EC 1.0-2.0 mS/cm. pH 5.5-7.0. Temperature: 20–32°C (tropical; frost-sensitive). Moderate to high light (DLI 12-20 mol/m2/day; tolerates partial shade). The semi-aquatic nature makes it ideal for NFT, DWC, and raft systems where roots are constantly in contact with water. Propagation by stem cuttings: every node roots rapidly in water. From cutting to harvestable plant: 3-4 weeks. Harvest by cutting stem tips; the plant branches and grows vigorously in warm, moist conditions. The flavor is at its peak in warm weather (the opposite of cilantro, which is at its worst in heat), making Vietnamese coriander the perfect warm-season cilantro substitute. For pho garnish, spring rolls, and laksa, fresh rau ram is traditional and irreplaceable. A few plants in a hydroponic system provide year-round supply in warm conditions.
Plan a setup with Vietnamese coriander
Verified against: university-of-florida-ifas. Last reviewed 2026-05-15.