Canna · Brussels, Brussels Capital, Belgium
When to sow cannas in Brussels
Main outdoor window
27 Apr - 25 May
The window this page is built around.
Timed from last spring frost
13 April
In Brussels, 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 Brussels
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
27 Apr - 25 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 Brussels
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 Brussels has passed and the soil has begun to warm, giving the roots the longest possible run before the cold returns.
Hardiness is not the obstacle here. Brussels is zone 8b, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.
Also in Brussels
Other flowers to time
Growing cannas in Brussels
When should I plant cannas in Brussels?
Aim for 27 Apr - 25 May in an average year. If you would rather not gamble on the weather, wait until 7 May - 4 Jun - by then frost has finished in nine years out of ten.
When will cannas be ready to harvest in Brussels?
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.