Potato · Imabari, Ehime, Japan
When to plant potatoes in Imabari
Main outdoor window
25 Feb - 11 Mar
The window this page is built around.
Timed from last spring frost
11 March
In Imabari, on your chosen risk.
Ready to pick
6 May - 25 Jun
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 Imabari
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.
Sow direct
25 Feb - 11 Mar
Two weeks before your last frost.
Harvest
6 May - 25 Jun
Potatoes through the year
Against the frost risk in Imabari
Why these dates
Plant two weeks before last frost so shoots emerge around the frost date. Earthing up buries vulnerable shoots and buys you a week of frost protection at a time.
Emerged foliage is blackened at -2C, though the plant usually regrows from the tuber with a yield penalty. Frost after emergence is the classic potato setback.
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. Potatoes are timed for direct sowing 2 weeks before it, and this page simply resolves those offsets against the frost date computed for Imabari.
The median frost-free season here is 282 days, against 70 to 120 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Imabari
Other vegetables to time
Growing potatoes in Imabari
When should I plant potatoes in Imabari?
Aim for 25 Feb - 11 Mar in an average year. If you would rather not gamble on the weather, wait until 11-25 Mar - by then frost has finished in nine years out of ten.
When will potatoes be ready to harvest in Imabari?
Expect to start picking around 6 May - 25 Jun, based on 70 to 120 days to maturity from the planting date calculated for this location.
How much frost will potatoes tolerate?
Emerged foliage is blackened at -2C, though the plant usually regrows from the tuber with a yield penalty. Frost after emergence is the classic potato setback.