Canna · Goyang-si, Gyeonggi-do, South Korea
When to sow cannas in Goyang-si
Main outdoor window
17 Apr - 15 May
The window this page is built around.
Timed from last spring frost
3 April
In Goyang-si, on your chosen risk.
Ready to pick
1 Jul - 31 Oct
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 Goyang-si
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 rhizomes
17 Apr - 15 May
After the last frost, once the soil has warmed. This crop is never fully dormant, so it cannot be planted bare-root in winter.
In flower
1 Jul - 31 Oct
Cannas through the year
Against the frost risk in Goyang-si
Why these dates
Plant rhizomes two weeks after the last frost, once the soil is 15C, 10cm deep. In a short season start them in pots under cover a month earlier, because a canna planted into cold soil sits and sulks and may not flower before autumn.
Foliage is killed at about -2C. Rhizomes survive in the ground from zone 8 upward under a thick mulch; colder than that, lift them after the first frost blackens the leaves and store them barely moist and frost-free.
Cannas are planted once and then left in place, so there is no sowing offset to resolve. Nor is there a dormant season to plant into: this crop keeps its leaves and keeps growing through the winter, which is exactly why cold damages it. The window on this page therefore waits until the last frost in Goyang-si has passed and the soil has begun to warm, giving the roots the longest possible run before the cold returns.
Goyang-si sits in zone 7a, 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.
Also in Goyang-si
Other flowers to time
Growing cannas in Goyang-si
When should I plant cannas in Goyang-si?
Aim for 17 Apr - 15 May in an average year. If you would rather not gamble on the weather, wait until 26 Apr - 24 May - by then frost has finished in nine years out of ten.
When will cannas be ready to harvest in Goyang-si?
Expect to start picking around 1 Jul - 31 Oct, based on 90 to 120 days to maturity from the planting date calculated for this location.
How much frost will cannas tolerate?
Foliage is killed at about -2C. Rhizomes survive in the ground from zone 8 upward under a thick mulch; colder than that, lift them after the first frost blackens the leaves and store them barely moist and frost-free.