Watercress
Nasturtium officinale
Also known asGarden cress (related) · Brunnenkresse · Berro
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 6–11 (winter low around -23°C)
- Frost
- tolerates light frost
- Season
- cool (spring/fall)
Growing systems
Root mass: light.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Lava rock (Scoria) | neutral / inert | low | very high |
| Net pot, no medium (Bare-root) | - | - | - |
| 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 | 0.4 |
| vegetative | 3 | 1 | 2 | 1.2 |
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
One of the most naturally suited crops for aquaponics, given its native habitat of nutrient-rich flowing water. NFT or shallow raft systems replicate the natural growing environment perfectly. EC 0.8-2.0 mS/cm. pH 6.0-7.5. Temperature: 10–22°C (cool-season; above 25°C, the plant bolts and the leaves become very peppery). Moderate light (DLI 12-18 mol/m2/day). From seed or cutting to first harvest: 4-6 weeks. The plant spreads by rooting at nodes along the stems; a small starter amount colonizes the growing channel rapidly. Harvest by cutting the top 10–15 cm of growth; the plant resprouts from the cut stems. The flowing water of NFT and aquaponics systems produces the cleanest, crispest watercress. Watercress from stagnant water can harbor liver fluke (Fasciola hepatica) parasites in areas where the parasite is present; clean flowing water eliminates this concern. For commercial hydroponic growers, watercress commands premium prices ($8-15/kg) and the connection to flowing water systems makes it a natural aquaponics crop.