How to grow Watercress

Where to plant

Watercress naturally grows in clear, cool, flowing water. At home, grow it in a pot of rich, moist potting mix standing in a saucer or tray of water that you change every day or two, or in a constantly wet bog bed, in part shade. It grows best in cool weather and turns hot, tough and quick to flower in summer heat.

Watercress spreads easily by stem pieces and has become invasive in streams and springs in parts of the US. Grow it in containers and never put plants or trimmings into ponds, ditches or streams. Do not harvest wild watercress from water that livestock can reach, as it can carry liver fluke.

• Florida and the Gulf South: grow it from fall through early spring in part shade; summer heat ends it.
• Texas, the Desert Southwest and California: grow it from fall through spring in shade with constant water.
• Mid-South, Mid-Atlantic and Southern Plains: sow in early spring and again from mid-August; July heat stops the seed sprouting and makes young plants bolt.
• Northeast, Midwest, Mountain West, Northern Plains and the Pacific Northwest: sow in early spring and late summer; in a cool, shady spot it grows through summer.
• Hawaii: grow it in the cooler months or at higher elevations. Alaska: sow from May to July.

How to plant

1. Fill a pot with rich, moist potting mix and stand it in a saucer or tray of water.
2. Scatter the tiny seed on the surface and press it in, barely covering it.
3. Keep the surface wet; seedlings appear within about a week.
4. Thin to a few inches apart, or simply cut as a dense patch.
5. For a quicker start, root a few stems from a store-bought bunch in a glass of water; they root within days and can then be potted.

Watering and feeding

Never let watercress dry out. Keep the pot standing in water and replace the water every day or two so it stays fresh and cool; stale, warm water leads to rot and mosquitoes.

Feed lightly with a diluted liquid fertilizer every couple of weeks to keep leaves coming.

Harvesting

Start snipping the top few inches of stems once plants are about 4 to 6 inches tall, cutting just above a leaf node so they branch. Pick often, before flowering, for the mildest flavor; the leaves turn hot and bitter once flowers appear. Store stems in a glass of water in the fridge and use within a few days.

Growing in pots

A pot standing in a tray of fresh water is the easiest and safest way to grow watercress at home, as it keeps the plant contained and out of natural waterways.

Using it

Use watercress raw in salads and sandwiches, blend it into soups and sauces, or wilt it into stir-fries. Wash it well before eating.

Propagation and saving seed

Watercress roots readily from stem cuttings in water, which is the fastest way to start a pot.