Leafy green (aquatic)
How to grow watercress
Nasturtium officinale
You do not need a stream to grow watercress. Root shop-bought sprigs in a jar, or sow seed in March and April, then grow the plants in a pot of rich compost standing in a tray of clean water in sun or part shade. Change the water every two or three days and cut the shoots regularly from May to October. Fresh water and frequent cutting are what keep the leaves mild and the plants from flowering.
- Hardiness
- Hardy
- Position
- Sun to part shade
- Soil
- Permanently wet, fertile; cool fresh water ideal
- Ideal pH
- 6.5 to 7.5
- Water
- Very high, roots must stay in fresh water
- Feeding
- Moderate feeder
Sowing and planting watercress
WhenSow Mar to Apr or root supermarket sprigs; harvest May to Oct
Starting off
Sow March to April or August 0.5 cm deep in a seed tray of compost stood in water at 15 to 20 °C, germinating in 7 to 14 days. Easier still: stand bought sprigs in a jar of water on a windowsill for 7 to 10 days until roots form, then pot up. Take tip cuttings every spring to renew plants.
Spacing and planting
Plant rooted sprigs 10 to 15 cm apart in a trench or trough of rich compost, or 6 to 8 plants in a 30 cm pot standing in a 5 cm deep tray of water, so the compost stays saturated. One of the best crops for a container, as the water is easier to control than in a bed.
Varieties worth growing
- Aqua
- The named variety in most UK seed catalogues. Quick from seed and selected for growing in pots and damp soil rather than running water.
- Watercress (Nasturtium officinale, unnamed seed)
- Ordinary green watercress sold simply by its common name. Perfectly good, and the cheapest way to raise a lot of plants.
- Supermarket sprigs
- Bunched or bagged watercress with intact stems roots in water within about a week. The fastest start, and you know you like the flavour.
Watercress month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do. Pots kept in a cold greenhouse give a few leaves.
- February
Nothing to do. Order seed.
- March
Sow indoors in a tray stood in water, or root sprigs in a jar on a windowsill.
- April
Pot up rooted sprigs and seedlings, six to eight to a 30 cm pot. Harden off.
- May
Stand pots outside in their trays. Take the first cut once shoots reach 10 to 15 cm.
- June
Cut every two to three weeks. Change the water every two or three days.
- July
Move pots into part shade. Pinch out flower buds. Change the water daily in hot spells.
- August
Sow or take tip cuttings for a fresh autumn batch.
- September
Keep cutting. Growth is at its best again as the weather cools.
- October
Last outdoor cuts. Move a pot into a cold greenhouse or porch before hard frost.
- November
Light picking from pots under cover.
- December
Nothing to do. Keep the compost wet but stop feeding.
Feeding watercress
A moderate feeder in a small volume of compost that is constantly flushed with water, so nutrients wash out. Mix feed into the compost at potting and top up with a light dry top-dress once or twice while cutting.
Needs steady nutrients and, above all, constantly moist roots.
Feeding plan
At potting, April or May
Fruit & Vegetable Fertiliser 4-5-6
5 g per litre of compost, the bottom of the label range: 60 g mixed through a 30 cm pot of about 12 litres.
After the second or third cut, about June, and once more at least six weeks later, no later than early September
Fruit & Vegetable Fertiliser 4-5-6
2 g per litre as a top-dress, the low end of the label: 24 g scattered on a 12 litre pot and watered in from above. The label gives no interval for top-dressing pots, so stop at two in a season. Tip out and refill the tray the next day so the run-off does not sit and grow algae.
October to March
Nothing
No feed while growth is slow.
Signs to watch
Pale yellow, small leaves
Nitrogen short in a nutrient-poor tray
A light top-dress of the dry feed in the feeding plan, watered in
Purple-tinged, dull leaves in cold water
Phosphorus uptake slowed by cold, not shortage
Move to a warmer spot
Rotting stems and a sour smell
Stagnant water, not a nutrient fault
Refresh the tray every 2 to 3 days
Pests, diseases and problems
Small round holes peppering the leaves
Flea beetle, most active in warm, dry weather from April to August
Cover the pot with fine insect mesh, and keep the plants growing fast with fresh water. Raising the pot on a table reduces attacks.
Leaves stripped, green caterpillars on the stems
Caterpillars of the small and large white butterflies, June to October
Check the pot twice a week and pick them off, or keep it under fine mesh through summer.
Clusters of green or grey aphids on shoot tips
Aphids, often when plants are stressed by warm, stale water
Cut the affected shoots off and discard them, refresh the water, and let clean regrowth come through. Dunking the whole pot in a bucket of water for a few minutes dislodges most of them.
Ragged holes and slime, small snails on stems and pot rim
Slugs and snails drawn to the constant damp
Lift the pot and check under the rim and tray every few days. Standing the tray on a table or bench keeps most of them away.
Small white flowers appear, leaves become small and bitter
Flowering, brought on by long days, heat and infrequent cutting
Cut the whole pot back to 5 cm, move it into part shade, and keep cutting every two to three weeks. Start a fresh batch from cuttings if the plants are tired.
Green slime coating the tray and compost surface
Algae growing in warm, still, nutrient-rich water in full sun
Empty and scrub the tray, refill with clean water, and change it more often. Feed onto the compost, not into the tray, and move the pot out of the hottest sun.
Harvest and rotation
Harvest and storage
Cut shoots at 10 to 15 cm from May, 6 to 8 weeks from planting, with scissors 5 cm above the base, and keep cutting every 2 to 3 weeks to stop flowering; pinch out flower buds. A 30 cm pot gives 150 to 200 g per cut. Eat within a day or stand stems in a jar of water in the fridge for 3 days.
Rotation and companions
Rotation: brassica group, but as a container or stream-edge perennial it needs no rotation; renew plants from cuttings every year. Grow beside mint and land cress, which share the damp, shaded conditions; nothing else competes in a tray. Keep away from dry, sunny beds and from beds near livestock run-off.
Good to knowGrow in a pot standing in a tray of fresh water that you refresh often; never let it dry out.
Growing watercress in pots
A container is the best way to grow watercress in a garden. Use a 30 cm pot or a trough with drainage holes, filled with peat-free multipurpose compost, and stand it in a tray or washing-up bowl holding about 5 cm of water so the compost stays saturated. Rainwater is ideal, but clean tap water is fine. Change the water every two or three days, and daily in hot weather, because stale water is what makes stems rot. Part shade suits it from June to August. Never use water from a stream or pond that livestock or wildlife can reach.
Watercress: common questions
Can you grow watercress without running water?
Yes. Watercress grows well in a pot of compost standing in a tray of still water, as long as you replace that water every two or three days. It needs wet roots and fresh water, not a current.
Can you grow watercress from supermarket watercress?
Yes, as long as the stems are intact. Stand a few of the longest sprigs in a jar of water on a bright windowsill, change the water every day or two, and white roots appear from the leaf joints in about a week. Pot them up once the roots are 2 to 3 cm long.
Is it safe to eat watercress grown in a stream?
Not raw, unless you are certain no sheep or cattle graze upstream. Wild and stream-grown watercress can carry liver fluke, a parasite spread through water contaminated by livestock, and washing does not reliably remove it. Grow watercress for salads in clean tap water or rainwater, and cook anything gathered from the wild.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.
- Nasturtium officinale (common watercress)RHS
- Nasturtium officinaleBBC Gardeners' World Magazine