Water spinach
Ipomoea aquatica
Also known asKangkong · Ong choy · Rau muong · Pak boong · River spinach · Swamp morning glory
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 9–13 (winter low around -7°C)
- Frost
- frost sensitive (dies at first frost)
- Season
- year-round tropical
Growing systems
Root mass: moderate.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Lava rock (Scoria) | neutral / inert | low | very high |
| Pea gravel (Pea stone) | varies | very low | moderate |
| Soil-based mix (Potting soil) | varies | high | high |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.8 |
| vegetative | 4 | 1 | 2 | 1.5 |
Companion-growing notes
- Heavy uptake of nitrogen. Co-grown crops with the same demand will end up deficient even at "correct" EC.
- High transpiration. Regular reservoir top-ups needed during fruiting.
Aquaponics suitability
Compatible
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 supremely productive warm-weather hydroponic/aquaponic green, but with legal restrictions in the US. Check federal and state regulations before growing. EC 1.5-2.5 mS/cm. pH 5.5-7.0. Temperature: 25–35°C (tropical; frost kills the plant). High light (DLI 16-25 mol/m2/day). The semi-aquatic nature makes it ideal for NFT, DWC, and raft systems where roots are in constant water contact. Also grows directly in fish tank water or in flooded media beds. From cutting to first harvest: 3-4 weeks. Growth is extremely vigorous in warm, nutrient-rich water. Harvest by cutting the top 20–30 cm of growing tips; the plant resprouts rapidly from every cut node. Continuous harvesting every 1-2 weeks keeps the plant productive. For the classic stir-fry: cut stems into 5 cm pieces, stir-fry over very high heat with garlic, chile, and fermented bean paste or shrimp paste for 60-90 seconds. The stems should still be slightly crunchy. The productivity in warm aquaponics systems is unmatched by any other leafy green.
Legality
| Jurisdiction | Status | Notes |
|---|---|---|
| United States (federal) | restricted | USDA APHIS federal noxious weed; interstate movement requires permit. Possession rules vary by state. source verified 2026-05-13 |
| Florida | prohibited | Florida prohibited aquatic plant; cultivation requires special permit even indoors source verified 2026-05-13 |
| Texas | prohibited | Texas prohibited exotic aquatic species source verified 2026-05-13 |
| Arizona | prohibited | Arizona Department of Agriculture prohibited noxious weed list verified 2026-05-13 |
| California | permit required | CDFA permit required for cultivation verified 2026-05-13 |