Oca · Riga, Riga, Latvia
When to plant oca in Riga
Main outdoor window
30 Apr - 28 May
The window this page is built around.
Timed from last spring frost
30 April
In Riga, on your chosen risk.
Ready to pick
1 Nov - 31 Dec
If you plant at the start of the window.
The average last frost. Half of all years are later than this.
Step by step in Riga
Each window is a range, not a single day. Earlier in the range buys you a longer season; later in it buys you a safer one.
Plant tubers
30 Apr - 28 May
Around your last frost.
Harvest
1 Nov - 31 Dec
Oca through the year
Against the frost risk in Riga
Why these dates
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.
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.
Seed packets and extension guides express timing as weeks either side of the last spring frost, because that is the only reference point that travels. Oca are timed with planting out 0 weeks after it, and this page simply resolves those offsets against the frost date computed for Riga.
Riga sits in zone 6a, which is colder than this crop is rated for, so it will need winter protection or a container that can be moved under cover. The dates below still describe the right time of year; the open question is survival rather than timing.
The median frost-free season here is 176 days, against 180 to 210 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Riga
Other vegetables to time
Growing oca in Riga
When should I plant oca in Riga?
Aim for 30 Apr - 28 May in an average year. If you would rather not gamble on the weather, wait until 9 May - 6 Jun - by then frost has finished in nine years out of ten.
When will oca be ready to harvest in Riga?
Expect to start picking around 1 Nov - 31 Dec, based on 180 to 210 days to maturity from the planting date calculated for this location.
How much frost will oca tolerate?
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.