How to grow Watercress in New Zealand
Watercress is a peppery, nutritious leaf that loves wet feet. In the garden it grows best in shallow water trays, self-watering pots or permanently wet ground with a little shade, and it crops close to year round in mild areas. A bunch from the shop will often root in a glass of water.
📖 Our full guide: How to Grow Watercress in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | August to May | |
| Auckland | August to May | |
| Waikato & Bay of Plenty | August to May | |
| Central North Island | August to May | |
| Wellington & Lower North Island | August to May | |
| Nelson & Marlborough | August to May | |
| Canterbury | August to May | |
| Otago & Southland | September to April | Plant Sep to Apr so roots establish before the hard frosts. |
| Central Otago | September to March | Plant Sep to Mar so roots establish before the hard frosts. |
Not to be confused with: Garden cress, a quick, dry-land seedling crop, and nasturtium, which shares watercress's botanical name Nasturtium but is a different plant with a similar peppery taste.
Where to plant
Watercress needs constant moisture and a little shade. Grow it in a pot standing in a tray of water, a self-watering container, a shallow pond edge or a permanently wet patch of rich soil. In hot sun it needs even more water.
- Northland to Canterbury: sow or plant at most times of year; it crops close to year round in Auckland.
- Otago, Southland and Central Otago: plant from spring to autumn so plants establish before the hard frosts; growth slows in the cold.
How to plant
- Sow seed in clumps of two or three seeds about 20 cm apart in moist, rich soil or potting mix, cover lightly and keep wet.
- Or stand a few stems from a shop bunch in a glass of water; they root within a week or two and can then be planted.
- Stand pots in a saucer or tray of water so the mix never dries out.
Watering and feeding
Keep watercress wet at all times; it wilts and turns bitter when dry. Change the water in trays regularly so it stays fresh. Feed every couple of weeks with a liquid fertiliser.
Pruning and care through the year
- Cut regularly to keep fresh, leafy shoots coming.
- Pinch out flower buds, as flowering ends leaf production.
- Sow or root new pieces every few months to keep a young, productive supply.
- Watch for slugs, snails and aphids.
Harvesting
Cut the tender shoots with scissors when the plants are 10 to 15 cm tall, about eight weeks from planting, leaving the base to regrow. Use it fresh in sandwiches, salads and soups.
Growing in pots
A pot of rich potting mix standing in a tray of water is the easiest way to grow watercress. Keep the tray topped up, refresh the water often, and grow it in part shade in summer.
Varieties
- Watercress (Common)
Companion planting
Watercress likes the same damp, shaded conditions as a few other herbs.
Good companions
Pests and diseases
Garden watercress has few pests. The bigger safety issue is wild watercress.
Pests to watch for
- Aphids Small insects clustered on shoot tips.
- Slugs and snails (slugs and snails) Leaves eaten in damp weather.
- Slugs
- Snails
Diseases to watch for
- Leaf spot Small brown spots on the leaves.
- Downy mildew Yellow patches with grey growth underneath in cool, damp weather.
Common questions
Can I grow watercress without a stream?
Yes. Grow it in a pot of rich potting mix standing in a tray of water, or in a self-watering container, and never let it dry out.
Is it safe to eat wild watercress?
Take care. Watercress growing in streams and drains on farmland, where sheep or cattle graze, can carry the cysts of liver fluke, which is present in New Zealand. Cooking kills the parasite. Home-grown watercress in clean water avoids the risk.
How do I grow watercress from a supermarket bunch?
Stand a few healthy stems in a glass of water on a bright windowsill. Roots form within a week or two, and the rooted stems can be planted in a wet pot.
Why is my watercress bitter?
It has dried out, been in hot sun, or started to flower. Keep it constantly wet, give it some shade and pinch out flower buds.
When can I pick watercress?
Once the shoots are 10 to 15 cm tall, about eight weeks after planting. Cut with scissors and it regrows.
Sources we checked: Yates NZ: How to grow watercress; VetEnt: Liver fluke (fascioliasis) in New Zealand; US CDC: About Fasciola.