Vegetable · Cyperaceae
When to plant water chestnuts
Grown in a flooded container or a pond margin, and grown for the corms that form in the mud at the end of the season rather than for the rush-like top.
Plant out
2 weeks after
Counted from your last spring frost.
Days to maturity
180-220
From sowing to a first picking.
Frost tolerance
Tender
How much cold the plant itself will take.
Those weeks become real dates once you name a place.
Timing, in frost-relative terms
Seed packets rarely give calendar dates, because a date that suits one latitude is wrong at another. They give offsets from the last spring frost instead, and those offsets are what make water chestnuts plantable anywhere.
- Plant out 2 weeks after the last frost.
- Expect 180–220 days to maturity, counted from sowing.
Getting the timing right
Plant corms two weeks after the last frost into 5cm of standing water. Drain in autumn once the tops yellow, then dig the corms out of the drying mud.
Frost tolerance
Top growth is killed at 0C, which is the signal to drain and harvest. Corms need around 200 frost-free days to size up.
Classified as tender, with damage expected below 0°C (32°F)32°F (0°C).