How to grow watercress
Nasturtium officinale · Brassicaceae · Vegetable
Watercress is a cool-season vegetable in the Brassicaceae family, grown either from a direct sowing or from transplants. It wants full sun, though it tolerates a little afternoon shade in hot regions and plenty of water, especially in hot weather. From sowing to first pick is about 50–60 days. It handles frost well and a light freeze often improves the flavour.
Grower’s note: A true water-lover - grow it in a wide, shallow container kept standing in an inch or two of water (top it up or change it often so it does not stagnate), or in a bog-style bed that never fully dries out. Snip stems above a leaf node for repeat cut-and-come-again harvests. It also roots readily from a bunch of fresh grocery-store watercress stood in a glass of water.
Sowing
Sow about 0.25″ deep, into soil between 45–70°F — germination is quickest near 60°F. Germination takes a week or two (7–14 days). For an early crop, start seed indoors about 4 weeks before your last spring frost and grow it under bright light.
Spacing & layout
Give each plant about 4″ along the row with roughly 12″ between rows. On a square-foot grid that is 9 per square foot. Allow at least 6″ of loose, workable soil for the roots. It grows well in containers at least 6″ deep.
Fitting it to your season
As a cool-season crop, watercress does its best growing in the mild weather of spring and fall and tends to bolt or turn bitter in summer heat. A second sowing in late summer, timed to mature as the weather cools, is usually the better crop of the year — and light frost only sweetens it.
Quick facts
When to plant watercress
Companions
No strong companions recorded.
No strong antagonists recorded.
Common problems
Pests: aphids, flea beetle, snails.
Diseases & disorders: root rot, leaf spot.
Same family (Brassicaceae)
Rotate these so they don’t follow each other in the same bed year to year.
Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.