Persian buttercup · Hamhŭng, South Hamgyong, North Korea
When to sow persian buttercups in Hamhŭng
Main outdoor window
9-23 Sep
The window this page is built around.
Timed from last spring frost
20 April
In Hamhŭng, on your chosen risk.
Ready to pick
1 Apr - 30 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 Hamhŭng
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 the corms
9-23 Sep
Four to six weeks before your first frost, so roots form before the ground cools.
In flower
1 Apr - 30 Jun
Persian buttercups through the year
Against the frost risk in Hamhŭng
Why these dates
Where winters stay above about -7C, plant in autumn for spring flowers - this gives much the better crop. In colder gardens, start the corms indoors in late winter and plant out around the last frost, or grow them in a cold frame. Soak the claws for three or four hours before planting, points downward, 5cm deep.
Hardy only to about -7C, so autumn planting is limited to zone 8 and warmer. The foliage takes a light frost; a hard one kills the plant. It also stops flowering in real heat, so a hot spring simply ends the season early.
Persian buttercups are anchored to the first autumn frost rather than the last spring one, so the planting window on this page counts backwards from the end of the season in Hamhŭng instead of forwards from its start.
Hamhŭng 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 185 days, against 90 to 120 days to first flower for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Hamhŭng
Other flowers to time
Growing persian buttercups in Hamhŭng
When should I plant persian buttercups in Hamhŭng?
Aim for 9-23 Sep in an average year. If you would rather not gamble on the weather, wait until 2-16 Sep - by then frost has finished in nine years out of ten.
When will persian buttercups be ready to harvest in Hamhŭng?
Expect to start picking around 1 Apr - 30 Jun, based on 90 to 120 days to maturity from the planting date calculated for this location.
How much frost will persian buttercups tolerate?
Hardy only to about -7C, so autumn planting is limited to zone 8 and warmer. The foliage takes a light frost; a hard one kills the plant. It also stops flowering in real heat, so a hot spring simply ends the season early.