How to grow watercress at home, from seed or cuttings

Watercress breaks the usual rules for growing herbs indoors. Most herbs die from too much water. Watercress wants wet feet, and what kills it is water left to go stale. For a quick profile of the plant, see watercress at a glance.

Watercress growing conditions at a glance

These are the numbers to aim for.

Need	What watercress wants
Water at the roots	Always wet. The pot stands in 1 to 2 inches of water.
Fresh water	Change it at least twice a week, and every day or two in a warm room
Light	Your sunniest window, or 14 hours under a grow light
Room	60 to 70°F is best. It still grows below 60°F, only slower.
Tray water	Keep it cooler than about 78°F
Soil	Bagged potting mix, never garden soil
Seed to sprout	About 1 week (3 to 14 days)
Stem to roots	About 1 week
Seed to first cut	4 to 6 weeks
Regrowth after a cut	3 to 4 weeks

How to grow watercress in a pot, no running water needed

You do not need a stream or a pump. Stand a pot of wet potting mix in a tray of water, and swap the water often. Utah State University suggests the same thing: a pot in a bucket with 2 to 3 inches of water.^[1]

The swap matters. Still water goes stale, starts to smell, and rots the stems at the base.

1. Pick a pot about 6 to 8 inches wide with holes in the bottom. Plastic is fine. Our guide on how to pick a pot for herbs covers sizes.
2. Fill it with bagged potting mix, and soak it until water runs out the bottom. Most bags are peat with perlite or vermiculite, which suits watercress fine.
3. Stand the pot in a tray or bowl with no holes. Keep 1 to 2 inches of water in the tray, so the bottom of the mix sits in water.
4. Change the tray water at least twice a week. In a warm room, or if it smells, change it every day or two. Rinse the tray each time.
5. Use a dark tray, not a clear one. Light on still water grows green algae.

A deep tray with no holes makes a good water tray for one or two pots.

How to grow watercress from seed

Sprinkle the seed on top of wet mix, keep it wet, and look for sprouts in about a week. Sow it straight into the pot it will live in, so you never have to move the seedlings.

Buy seed labeled Nasturtium officinale. Garden cress and upland cress are different plants with similar names.

1. Set up the pot and tray as above, with the mix soaked.
2. Sprinkle a pinch of seed thinly over the top, and press it down with your palm. Do not cover it. The seeds are tiny, and they sprout on the surface.^[2]
3. Keep the top wet until sprouts show. The tray does most of the work, but mist the surface on a warm, dry day.
4. A cool room is fine. The seed sprouts anywhere from 41 to 77°F.
5. Leave the seedlings as a clump. You cut watercress like a small lawn, so there is no need to thin it.

Your first cut comes 4 to 6 weeks after you sow.^[2] If you want a faster crop, you can also grow it as microgreens and cut it young.

How to grow watercress from supermarket stems

A bunch of fresh watercress from the store will root in a glass of water in about a week. It is the fastest way to start.

1. Pick the freshest bunch you can find. One sold with its roots still on is even better.
2. Cut stems about 4 inches long, and pull off the lower leaves.
3. Stand them in a glass of water on a bright windowsill. Change the water every day or two.
4. When the roots are about 1 inch long, plant 3 to 5 stems in a pot of wet mix. Push them in up to the first leaves, then stand the pot in its tray.

Rooted stems already have leaves, so you can start picking sooner than from seed.

Can watercress grow in just water?

Yes, for a while. Stems keep growing in a glass of water, but tap water holds almost no plant food. After a few weeks, the leaves turn pale and small.

There are two fixes. Move the rooted stems into potting mix, as above, or add a weak plant food made for growing in water. Researchers in Hawaii have grown whole crops of watercress this way, in tanks with no pump at all. Our lettuce guide explains the no-pump jar method, and watercress grows the same way.

Keep the water cool and dark. Water warmer than about 78°F slows growth. A clear jar in the sun grows algae, so wrap it or use one you cannot see through.

How much light does watercress need indoors?

Watercress needs more light than most people think. Give it your sunniest window,^[1] ideally one that faces south. Or give it about 14 hours a day under a grow light, 6 to 12 inches above the leaves.^[3]

It does poorly in deep shade.^[4] In a dim spot, it grows long, thin, and pale.

Keep a grow light to about 14 hours, not 16 or more. Watercress starts to flower as the days get longer,^[4] and once it flowers, the flavor fades.^[1]

Hot sun through glass can warm a small tray of water. If the tray feels warm, pull the pot back from the glass at midday, or use an east window in summer. Turn the pot every few days so it grows evenly. For lamps and timers, see our guide to grow lights for herbs.

Keep it cool

Watercress grows best at 60 to 70°F. It still grows below 60°F, only more slowly. Above 85°F the taste goes downhill, so keep it away from heaters, vents, and the top of the fridge.

How to harvest watercress so it keeps coming back

Cut the stems back to about 4 inches tall with scissors.^[1] New shoots grow from the leaf joints, and you can cut again in 3 to 4 weeks.^[2] Never cut lower than about 1½ inches, or it has little left to grow back from.

You can also pick single leaves at any time. Pinch off flower stalks as soon as you see them.

Watercress is a perennial, a plant that lives for years, and one pot gives you months of picking. When it turns woody or keeps trying to flower, start a fresh pot from a few of its own stems.

It needs little food. Add a weak liquid plant food to the tray water every few weeks. Our watercress care guide covers feeding and keeping a pot going. For the harvest itself, here are ways to use watercress in the kitchen.

Is homegrown watercress safe to eat raw?

Yes. Watercress you grow in tap water is the safe kind to eat raw. The CDC says raw wild watercress can carry liver fluke, a parasite from places where farm animals graze.^[5] Rinse your harvest as you would any greens.

Why is my watercress leggy or yellow? Common problems

Most problems come down to light, stale water, or heat.

Symptom	Likely cause	Fix
Long, thin, pale stems leaning to the window	Too little light	More light. Cut the long stems back so it regrows bushy.
Leaves turning yellow or small	Out of plant food	Weak liquid plant food, or move stems from water into potting mix.
Cloudy or smelly water, slimy stems at the base	Stale water	Fresh water, a rinsed tray, and soft stems pulled out. Change it more often.
Green film on the water or tray	Algae, from light on still water	Dark tray or jar. Rinse it at each change.
Flower stalks, harsh or bitter leaves	Long days or heat	Pinch off flowers, move it somewhere cooler, and keep lights to 14 hours. More on why herbs bolt.
Tiny green bugs on the tips, sticky leaves	Aphids	Rinse them off under the tap, and use insecticidal soap if they come back. More on getting rid of aphids and other indoor pests.
Tiny white flies, or fine specks on the leaves	Whiteflies or spider mites	Insecticidal soap, sprayed under the leaves too.

Questions & answers

How long does watercress take to grow?

Seeds sprout in about a week, and your first cut comes 4 to 6 weeks after you sow. Supermarket stems root in about a week, and you can pick them sooner. After each cut, it grows back in 3 to 4 weeks.

Does watercress come back every year?

Yes. It lives for years and grows back after each cut, with 3 to 4 weeks between cuts. Indoors, start a fresh pot from your own stems when the old one gets woody.

Can you grow watercress indoors?

Yes. It needs a sunny window or a grow light. Stand the pot in water, and change it twice a week. Winter is a good time to grow it, because it likes a cool room.

Is watercress easy to grow?

Yes, once the pot is set up. You cannot give it too much water. The two things that go wrong are stale water and too little light.

Where does watercress grow?

In the wild, it grows at the edges of slow streams, rivers, springs, and ditches. At home, it grows in any pot that stands in a tray of water.

References

1. Utah State University Extension, How to grow watercress in your garden. https://extension.usu.edu/yardandgarden/research/watercress-in-the-garden ↩︎ ↩︎ ↩︎ ↩︎

2. University of Hawai’i CTAHR, Growing watercress from seed by a non-circulating hydroponic method. https://www.ctahr.hawaii.edu/hawaii/downloads/Growing_Watercress_by_a_Non-circulating_Hydroponic_Method.pdf ↩︎ ↩︎ ↩︎

3. University of Illinois Extension, Grow herbs and lettuce indoors this winter. https://extension.illinois.edu/blogs/good-growing/2017-11-17-grow-herbs-and-lettuce-indoors-winter ↩︎

4. U.S. Fish and Wildlife Service, Watercress (Nasturtium officinale) ecological risk screening summary. https://www.fws.gov/sites/default/files/documents/Ecological-Risk-Screening-Summary-Watercress.pdf ↩︎ ↩︎

5. Centers for Disease Control and Prevention, About Fasciola. https://www.cdc.gov/liver-flukes/fasciola/index.html ↩︎