How to Grow Watercress
Nasturtium officinale
When to Start
Direct sow outdoors as soon as soil reaches 5°C — typically early to mid spring. Hardy enough to tolerate light frosts.
Don't know your frost date? Find it here →
Growth Stages
Approximate days from start
Care Essentials
- Watercress grown in flowing water or regularly refreshed water rarely needs feeding. In containers or damp soil, apply a dilute balanced liquid fertiliser every 3–4 weeks during the growing season.
- Harvest regularly by snipping stems just above the water line to encourage bushy regrowth. Watercress bolts quickly in warm weather, so harvest frequently and resow in mid-summer for a second autumn crop.
Companion Planting
—
Growing Conditions
Get a personalized schedule for Watercress based on your exact frost dates
Start planning freeEnter your last frost date to see your dates
- Direct sow
- —
Want your full season plan with reminders? Try Leaftide free
Spacing & Planting
| Plant spacing | 15 cm |
| Row spacing | 15 cm |
| Sow depth | 0 cm |
| Mature height | 15 cm |
| Mature spread | 30 cm |
Care Guide
- Feeding
- Watercress grown in flowing water or regularly refreshed water rarely needs feeding. In containers or damp soil, apply a dilute balanced liquid fertiliser every 3–4 weeks during the growing season.
- Watch for
-
- Watercress leaf beetle (small black beetle skeletonising leaves)
- Aphids on young shoots
- Powdery mildew in dry spells
- Slugs on young seedlings
Pests & Diseases
Pest Watercress Leaf Beetle
Identification: Small metallic blue-green beetles (about 3 mm) and their pale yellow larvae feeding on leaves, creating small round holes and a characteristic pitted appearance. Damage is most visible from late spring through summer.
- Remove adults and larvae by hand and drop into soapy water; most practical for small container plantings.
- Encourage natural predators such as ground beetles and birds by maintaining diverse planting nearby.
- Covering plants with fine insect mesh immediately after sowing or planting provides effective physical exclusion.
- Pyrethrin-based insecticides can be used as a last resort but are rarely necessary for container crops and must not be used near waterways.
Pest Aphids
Identification: Dense colonies of small soft-bodied insects (often pale green or grey) on the undersides of leaves and on growing tips. Honeydew deposits cause a sticky sheen and may encourage sooty mould growth.
- Blast off with a strong jet of water, directing it at leaf undersides.
- Introduce or encourage ladybirds, lacewings, and hoverfly larvae as natural predators.
- Spray with insecticidal soap solution in the early morning.
- Pyrethrin-based spray as a last resort; never apply to plants growing in or beside open water.
Pest Slugs
Identification: Irregular holes in leaves with silvery slime trails. Damage is most severe at seedling stage and on soft new growth after harvest.
- Apply wool pellets or copper tape barriers around container edges.
- Hand-pick at night when slugs are most active.
- Use nematode treatments (Phasmarhabditis hermaphroditis) watered into surrounding soil in warm, moist conditions.
- Ferric phosphate pellets are wildlife-safe; do not use metaldehyde near water.
Disease Powdery Mildew Erysiphe cruciferarum
Symptoms: White powdery coating on the upper leaf surface, starting as small patches. Affected leaves may curl, yellow, and die prematurely. Most prevalent in warm, dry spells despite the plant's moisture needs.
Treatment: Remove and destroy affected leaves. Spray remaining foliage with a 1:9 milk-to-water solution or dilute sodium bicarbonate spray. Ensure good air circulation and avoid overcrowding plants.
Prevention: Do not overhead water in the evening. Space plants to allow air movement. Harvest regularly to prevent dense canopy buildup that traps humidity.
Disease Downy Mildew Peronospora nasturtii
Symptoms: Yellow patches on the upper leaf surface corresponding to a grey-purple downy fungal growth on the underside. Leaves yellow rapidly and collapse. Most severe in cool, humid conditions.
Treatment: Remove and destroy all affected material promptly. Improve air circulation by thinning plants. There are no chemical treatments approved for home use on watercress.
Prevention: Avoid overhead watering. Do not crowd plants. Rotate container growing medium annually. Never compost affected material.
Growing Conditions
| Min. soil temperature | 5°C |
| Germination temperature | 10–18°C |
| Base growth temperature | 5°C |
| Min. daylength to start | 8h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Watercress?
- Plant Watercress 15cm apart with 15cm between rows.
- Is Watercress frost hardy?
- Watercress is classified as Hardy.
Plan Watercress in your garden — get personalized frost-date scheduling
Start planning free