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Quick Facts
- Sowing window
- Sow from March to July in pots or trays of moisture-retentive compost.
- Harvest window
- Snip peppery shoots from late spring onwards once plants are growing strongly.
- Difficulty
- Easy
- Container suitability
- Use a pot or trough at least 15–20cm deep filled with moisture-retentive compost. Keep it constantly moist with clean fresh water, but refresh standing water frequently rather than allowing it to stagnate.
- Frost sensitivity
- Protect from hard frost
- Typical time to harvest
- Baby leaves can be cut within 4–6 weeks; headed lettuces usually need 8–14 weeks.
SOW
When to Sow Watercress in the UK
Sow from March to July in pots or trays of moisture-retentive compost.
Use that window as a practical starting point rather than a fixed deadline. In colder or exposed areas, delay outdoor sowing and planting; in mild sheltered areas, the earlier end of the range may work. Tender crops should remain protected until frost risk has passed.
Sowing Indoors
Start in modules for an earlier crop or where slugs are troublesome. Keep seedlings cool and bright; warm indoor conditions produce weak, stretched growth.
Sowing Outdoors
Sow Watercress thinly and shallowly, then thin or transplant before plants crowd. Small repeat sowings are more useful than one large batch.
PLANT
Spacing and Planting Out
Use 15cm spacing for small leaves and mini heads, 25–30cm for larger lettuces, chicory and chard. Good airflow reduces rotting at the base.
Before planting outside, harden off indoor-raised plants over 7–10 days unless the crop is fully hardy and already accustomed to outdoor conditions. Water the planting hole or container first and avoid leaving young roots exposed to sun or wind.
SMALL SPACES
Growing Watercress in Pots and Containers
Use a pot or trough at least 15–20cm deep filled with moisture-retentive compost. Keep it constantly moist with clean fresh water, but refresh standing water frequently rather than allowing it to stagnate.
Container checklist
- Use drainage holes and raise pots slightly so surplus water can escape.
- Fill with fresh peat-free compost suited to edible crops.
- Leave a watering lip below the rim and check pots more often in sun or wind.
- Use a strong support at planting time if the mature crop will climb or become top-heavy.
CARE
Watering and Feeding
Never let the compost dry. Use clean water and refresh any saucer or tray regularly. Feed lightly only if growth pales.
Variety note: Keep compost constantly moist with fresh water, but do not leave home-grown pots in stagnant water.
WATCH FOR
Common Problems
Bolting
Heat, dry roots and crowding can trigger flowering. Keep plants cool and moist and sow bolt-prone crops at the recommended time.
Slugs and snails
Raise containers, check at night and remove hiding places. Protect young plants before damage becomes severe.
Bottom rot or mildew
Crowding, wet foliage and stale air are common causes. Improve spacing and water the compost rather than the leaves.
PICK
Harvesting Watercress
Snip peppery shoots from late spring onwards once plants are growing strongly.
Baby leaves can be cut within 4–6 weeks; headed lettuces usually need 8–14 weeks. Harvest in the coolest part of the day where practical and handle produce gently. Regular picking encourages continued cropping in fruiting and cut-and-come-again plants.
GROW TOGETHER
Companion Plants
Radishes, spring onions, chives and compact herbs can share a wide trough when spacing allows. Their different shapes use space efficiently, but regular watering remains the main benefit.
QUESTIONS
Frequently Asked Questions
Can I grow Watercress in pots?
Use a pot or trough at least 15–20cm deep filled with moisture-retentive compost. Keep it constantly moist with clean fresh water, but refresh standing water frequently rather than allowing it to stagnate.
How long does Watercress take to harvest?
Baby leaves can be cut within 4–6 weeks; headed lettuces usually need 8–14 weeks.
Why is my Watercress bolting?
Hot weather, dry compost, root restriction or sowing at the wrong season can trigger flowering. Keep it cool and moist and make small repeat sowings.