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 crops most naturally suited to aquaponics, given its native habitat of nutrient-rich flowing water. NFT or shallow raft systems replicate that environment well. EC 0.4-1.8 mS/cm. pH 6.5-7.5. Temperature: 10–20°C (cool-season; above 25°C the plant bolts and the leaves turn very peppery). Moderate light (DLI 10-16 mol/m2/day). From seed or cutting to first harvest: 4-6 weeks. The plant spreads by rooting at the nodes, so a small starter amount colonizes the channel quickly. Harvest by cutting the top 10–15 cm of growth and it resprouts from the cut stems. Flowing water in NFT and aquaponics gives the cleanest, crispest watercress; watercress from stagnant water can harbour the liver fluke (Fasciola hepatica) where the parasite is present, while clean flowing or controlled systems remove that concern. Watercress commands premium prices and its link to flowing-water systems makes it a natural aquaponics crop.