Start indoors or direct sow?

Start indoors for controlled moisture and easy early growth, then transplant to a very wet garden site or container. Direct sowing also works where you can keep the seedbed continuously moist and free of crusting.

When to start Watercress seeds

Start indoors about 4 to 6 weeks before the last spring frost, or direct sow around the last frost date in cool regions. Sow additional crops in late summer for fall harvest, avoiding the hottest part of summer where possible.

How to sow the seeds

Press seeds onto the surface of moist seed-starting mix, then cover only very lightly with fine mix or vermiculite. Use shallow cells or trays with drainage set in a waterproof tray, keeping the growing medium constantly moist.

Germination

Seeds often germinate in 5 to 10 days. They do best at roughly 50 to 70 F with constant moisture and no standing water over the tiny seedlings.

Seedling care

Provide bright light and keep the medium wet by maintaining a shallow water reservoir beneath the containers after emergence. Thin crowded seedlings, refresh stagnant water, and provide gentle airflow to reduce damping off.

Transplanting & hardening off

Harden seedlings off for about a week, then move them after the danger of severe freezing has passed to a clean, consistently wet site. Plant into saturated soil or a container with shallow clean water, keeping crowns above deep water.

Tips

Use clean water and avoid collecting watercress from unknown natural waterways. Harvest outer stems regularly to keep plants branching and productive.

General seed-starting guidance for US home gardens; timing depends on your local frost dates and variety. Page updated Aug 4, 2026.