Vegetable · Oxalidaceae
When to plant oca
Only begins forming tubers when the days shorten below about eleven hours, which makes the first autumn frost date the whole story.
Plant out
0 weeks after
Counted from your last spring frost.
Days to maturity
180-210
From sowing to a first picking.
Hardy in USDA zones
8a to 10a
Winter cold sets the limit here, not the calendar.
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 oca plantable anywhere.
- Plant out 0 weeks after the last frost.
- Expect 180–210 days to maturity, counted from sowing.
- Hardy in USDA zones 8a–10a.
Getting the timing right
Plant tubers after the last frost. Do not lift until several weeks after the tops are frosted - almost all the crop forms in that final window, and digging early gets nothing.
Frost tolerance
Foliage is killed around -2C, but tuber formation happens in the weeks just before and after that. In short-season climates a fleece over the plants buys the time the crop needs.
Classified as tender, with damage expected below -2°C (28.4°F)28.4°F (-2°C).