Vegetable · Brassicaceae
Watercress
Nasturtium officinale
Kept in cool, clean, moving water, watercress turns a sunny sill into a small, peppery harvest from spring through fall.
Full sun
Every 1–3 days
32–77°F · 0–25°C
50–60 days
Overview
Watercress brings a quiet, kitchen-garden charm to a home, the kind of edible that looks as good on the windowsill as it does on the plate. Its peppery bite dresses up a weeknight salad or sandwich, and it belongs to the mustard family with cabbage and radish rather than the climbing garden nasturtium it is sometimes taken for. In the wild it settles along cool, clean streams across much of the temperate world, and that watery character is part of its appeal indoors.
What sets it apart as a houseplant of sorts is the way it lives in water. The roots stay wet at all times, ideally in flowing spring water, though a pot standing in a simple tray of water suits a kitchen counter or a bright bathroom sill just as well. Keep that water cool and moving, and the plant supplies fresh greens faster than most pots can manage.
Few edibles slip so easily into a daily routine. A quick pinch of the shoots while the kettle boils keeps it lush and tender and ready to snip into the next meal. Let the water warm or sit still, though, and it bolts, turns bitter, and thins, a gentle reminder that this is a cool-season companion.
Care
The short version: keep cool, clean water around the roots at all times, set it in full sun to part shade, and snip often so the leaves stay tender and the plant holds back from flowering.
Light
Watercress settles happily into full sun to partial shade, which makes it flexible about where it sits at home. A bright sill gives the fullest growth, while a spot with a little afternoon shade keeps the water and leaves cooler through summer.
Water
Water is the heart of keeping it well. The roots stay submerged or in constantly saturated soil, never drying out, so a pot standing in a tray of water is the simplest setup for a counter or sill. Cool, clean, flowing or spring water is ideal, and refreshing the tray every 1 to 3 days keeps it cool, clean, and full of oxygen.
Soil
Give it rich, mucky loam at a water's edge, or a soil-filled pot standing in water for indoor life. It is easy about pH, from 6.5 to 8.0, leaning toward the neutral-to-alkaline side that recalls the limestone streams it comes from.
Temperature
Watercress favors cool conditions, from about 32°F to 77°F (0°C to 25°C), so a cooler room or a bright bathroom suits it well. It shrugs off frost but bolts and turns bitter once the water warms past that range, which is where a shadier summer spot helps.
Humidity
As a water plant it likes the air humid, from 70% up to nearly 100%, and the standing water around its roots usually keeps the surroundings moist enough on its own. That makes it an easy fit for the naturally damp corners of a kitchen or bath.
Feeding
In clean flowing water the plant feeds itself and needs no fertilizer. In a container, a dilute balanced liquid feed monthly through spring and summer keeps it lush, since still water on a sill cannot supply everything on its own.
Pruning
Regular pinching and harvesting of the shoot tips keeps the planting full and tender, ideal for a countertop crop you pick from often. Snip out flower stalks as soon as they appear, since flowering turns the leaves bitter and tells the plant to wind down.
Repotting
Lift and divide the mat about once a year, or sooner when the stems crowd and new growth slows. Stems creeping over the edge of the tray are the cue to give it a fresh, roomier home.
Size & spacing
The plant stays low at 4 to 20 inches (10 to 50 cm) tall but spreads into a mat 12 to 35 inches (30 to 90 cm) across, so it reads as a low, spreading green rather than a tall feature. Give that spread room on a wide sill, or thin it so the water keeps moving through.
When to plant
Watercress keeps to the cooler rhythm of the year, thriving in spring and fall and fading through summer heat. Surface-sow the seed in late winter to early spring, move young plants outdoors once hard frost has passed, and gather leaves from spring through fall, or year-round where the water stays cool and moving.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring, surface-sown on constantly moist medium
- Plant: Spring after danger of hard frost, or fall in mild-winter regions
- Harvest: Harvest leaves spring through fall (year-round in mild flowing water); small white cross-shaped flowers appear late spring to summer
Hardiness
USDA hardiness zones: 4–10
Temperature: down to -34°C
Troubleshooting
Most watercress troubles trace back to the water or the season rather than anything you have done wrong. Warm, still water and summer heat cause the bulk of them, and the leaves signal the change early. Match what you see below and adjust the setting before the whole planting loses its looks.
Pale, yellowing leaves on a mat that has lost its luster
The usual culprit is warm, still water. Once the water stops moving it loses oxygen and warms, and the older leaves pale first, dulling the whole planting. Refresh or circulate the water to cool it, move the pot into partial shade through the summer heat, and offer a dilute balanced fertilizer if it lives in a container.
Fix:
- Refresh or circulate the water to keep it cool and oxygenated
- Move to partial shade during summer heat
- Apply a dilute balanced fertilizer when grown in containers
Flower stalks rise and the leaves turn harsh and bitter
This is bolting, brought on by heat. Once the water climbs past about 75°F (24°C), flower stalks shoot up, the leaves shrink, and the peppery bite turns harsh on the plate. Pinch out the flowering stems, move the plant to a shadier spot with cooler water, and if summer takes over, begin again from stem cuttings once the weather cools.
Fix:
- Harvest and pinch out flowering stems
- Provide shade and cooler water
- Restart from stem cuttings in the cooler season
Curled leaves marked with clustered bugs or tiny shot-holes
Two pests spoil the look here. Aphids gather on the leaf undersides and twist the new growth, while flea beetles punch the small round holes that freckle a leaf like buckshot. A strong jet of water clears both, and trimming away the badly chewed shoots restores a tidy planting.
Fix:
- Dislodge pests with a strong jet of water
- Remove and discard heavily infested shoots
Toxicity
This is a reassuring plant to keep around a home: watercress is a food crop, not a hazard. It is safe for cats, dogs, horses, rabbits, livestock, birds, and people alike, with no toxin in any part. The single caution is for people, and it turns on where the cress grew rather than the plant itself.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Watercress poses no risk to cats. A passing nibble does no harm, though the peppery leaves rarely tempt them for long.
Dogs None
It is safe for dogs, leaves and stems alike. A dog that gulps a big mouthful might get a touch of harmless gas, and nothing beyond that.
Horses None
Horses can graze it without concern. The sharp mustard tang tends to keep them from eating much of it anyway.
Rabbits Safe
Rabbits can share in watercress as part of a mixed green diet. Introduce it slowly, as with any new leafy vegetable, so the gut adjusts.
Livestock Safe
Cattle, goats, and sheep can browse watercress safely, since it holds no toxin to trouble grazing stock.
Birds Safe
Backyard hens and other birds peck at the tender leaves with no ill effect, and the greens lend a little variety to their feed.
People Safe
Watercress is a nourishing salad green, welcome raw or cooked at the table. The one real catch is wild plants, since cress foraged from water grazed by livestock can carry liver fluke parasites, so cook wild-harvested cress or grow your own in clean water before eating it raw.
Food-safety note for people (not pet toxicity): wild watercress from water that may be contaminated by grazing livestock can carry liver fluke (Fasciola) larvae and waterborne pathogens. Cook wild-harvested cress or grow it in clean, uncontaminated water before eating it raw.
Varieties
Most watercress grown at home is simply the wild species, but a couple of named types are worth a mention.
Improved Broad Leaved
A cultivated strain prized for larger, broader leaves and a fuller harvest than the wild plant provides.
Nasturtium microphyllum (one-row, small-leaved watercress)
A close relative with smaller leaves and single-rowed seeds that crosses freely with true watercress wherever the two share a spot.
How to propagate
Watercress multiplies with almost no coaxing, whether a few cuttings root in a glass on the sill or seed scatters across a tray of damp soil.
Stem cuttingsEasy
Any time during active growth, best in spring or fall · 1 to 2 weeks
Cuttings are the quickest way to begin, and they can be taken any time the plant is growing, with spring and fall the most rewarding. Cut stems about 4 to 6 inches (10 to 15 cm) long and stand them in a glass on the sill or press them into wet soil. They root at the nodes within 1 to 2 weeks, ready for their place.
SeedEasy
Spring, in cool moist conditions · 2 to 3 weeks to germinate and establish
Seed suits the cool, damp days of spring. Scatter the fine seed across the surface of a constantly moist medium rather than burying it, since it needs light and must never dry out. Allow it 2 to 3 weeks in cool temperatures to sprout and settle in.
Myths
Wild watercress is always safe to eat raw straight from the stream.
Cress gathered from water grazed by livestock can carry liver fluke larvae and other waterborne organisms you cannot see. The simple habit worth keeping is to cook wild-harvested cress, or grow your own in clean water, before eating any of it raw.
Edible watercress is the same plant as the ornamental garden nasturtium.
They share a peppery flavor and a common name, and there the likeness ends. Edible watercress is Nasturtium officinale in the mustard family, while the climbing garden nasturtium is Tropaeolum majus, a separate genus altogether.
Watercress needs deep running water and cannot be grown at home.
Flowing spring water is the ideal, but hardly a requirement for a home grower. A pot of rich soil standing in a tray of water, kept wet and refreshed, keeps a steady supply within reach on a windowsill or patio.