Watercress
Nasturtium officinale
Overview
A peppery, aquatic green that grows wild in clean streams across much of the world, watercress was recently ranked as the single most nutrient-dense food by CDC researchers. Its sharp, mustard-like bite comes from glucosinolates, making it both a culinary delight and a cancer-fighting powerhouse. Watercress has been eaten since Roman times and can be easily grown in containers with continuously moist soil.
Growing Conditions
Companion Planting & Soil
Good Companions
Planting Calendar
When to sow, transplant, and harvest by growing zone.
| Zone | Action | Months | Notes |
|---|---|---|---|
| Cold (1-2) | Transplant | May — Jun | Transplant to stream edge or pot set in water tray; needs constant moisture |
| Cold (1-2) | Harvest | Jun — Sep | Cut stems above waterline; regrows quickly; best before flowering |
| Cool (3-4) | Direct Sow | Apr — May | Direct sow in very moist soil or shallow water; press seeds into surface |
| Cool (3-4) | Harvest | May — Oct | Harvest young shoots continuously; peppery flavor |
| Moderate (5-7) | Direct Sow | Mar — Apr | Sow in boggy soil or shallow water; roots from stem cuttings readily |
| Moderate (5-7) | Direct Sow | Sep — Oct | Fall sow for cool-season harvest |
| Moderate (5-7) | Harvest | Apr — Jun | Spring harvest; flavor turns bitter in heat |
| Moderate (5-7) | Harvest | Oct — Dec | Fall harvest |
| Warm (8-9) | Direct Sow | Sep — Nov | Fall through winter crop; bolts in spring heat |
| Warm (8-9) | Harvest | Oct — Mar (wraps) | Harvest through cool months |
| Hot (10+) | Direct Sow | Oct — Jan (wraps) | Cool-season only; grow in shade with standing water |
| Hot (10+) | Harvest | Nov — Feb (wraps) | Winter harvest; must have constant water |
Uses
Culinary
- Peppery addition to salads, sandwiches, and soups
- Classic watercress soup (potage au cresson)
- Blended into pesto and compound butters
Medicinal
- Ranked #1 most nutrient-dense food by CDC nutrient density score
- Rich in glucosinolates with anti-cancer properties
- Extremely high in vitamins K, A, and C
Other Uses
- Aquatic or bog garden edible plant
- Natural water purifier in stream-fed systems
Safety Notes
Whilst the plant is very wholesome and nutritious, some care should be taken if harvesting it from the wild. Any plants growing in water that drains from fields where animals, particularly sheep, graze should not be used raw. This is due to the risk of it being infested with the liver fluke parasite[5, 244]. Cooking the leaves, however, will destroy any parasites and render the plant perfectly safe to eat[244]. May inhibit the metabolism of paracetamol [301].
