Chinese water chestnut
Eleocharis dulcis
Also known as: Matai, Ma tai, Chinese sedge, Eleocharis tuberosa, Pi qi
Quick facts
- Category
- roots bulbs
- Difficulty
- intermediate
- Days to harvest
- 180 to 270 days
- Harvest type
- single harvest then replant
- Spacing
- 30 cm between plants
Environment
- Temperature
- 18–32°C
- pH
- 6 to 7.5
- EC (hydroponic)
- 1.5 to 2.5 mS/cm
- Daily light
- 15 to 22 mol/m²/day
Climate and zones
- USDA zones
- 9 to 12 (winter low around -7°C or warmer)
- Frost tolerance
- frost sensitive (dies at first frost)
- Season
- warm (summer crops, frost-sensitive)
Viable growing environments:
- outdoor in growing season (annual)
- heated greenhouse
- indoor (heated home)
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
Chinese water chestnut works in:
- media bed (ebb and flow)
- 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 (chinese water chestnut works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Lava rock (Scoria) | neutral / inert | low | very high |
| 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 | 2 | 1 | 3 | 2 |
Companion-growing notes
- Heavy uptake of potassium. 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
An aquatic crop grown in waterlogged conditions, well-suited to aquaponics integration. Grow in large, shallow containers (30 cm wide, 15–20 cm deep) filled with waterlogged substrate (clay loam, aquatic planting soil) and 5–10 cm of standing water above the substrate surface. EC 1.5-2.5 mS/cm (the water surrounding the containers). pH 6.0-7.0. Temperature: 25–32°C (tropical; the corms form as days shorten in autumn, similar to oca). Full sun (DLI 18-25 mol/m2/day). Plant corms or divisions in spring. The rush-like stems grow throughout summer. Corms form at the tips of underground stolons in autumn. Harvest by digging through the waterlogged substrate in late autumn, feeling for the small, round corms. Yields: 0.5–2 kg per container. Peel the brown skin to reveal white flesh. Eat raw (sliced, crispy, mildly sweet) or add to stir-fries, salads, or dim sum fillings. The crunch of a fresh water chestnut is incomparably superior to the canned product.
Plan a setup with Chinese water chestnut
Verified against: university-of-florida-ifas, fao-fisheries-aquaculture. Last reviewed 2026-05-15.