Wallflower · Essen, North Rhine-Westphalia, Germany
When to sow wallflowers in Essen
Main outdoor window
29 May - 26 Jun
The window this page is built around.
Timed from last spring frost
17 April
In Essen, on your chosen risk.
Ready to pick
1 Apr - 31 May
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 Essen
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
29 May - 26 Jun
Six weeks after your last frost.
Move to final position
4 Sep - 2 Oct
20 weeks after your last frost.
In flower
1 Apr - 31 May
Wallflowers through the year
Against the frost risk in Essen
Why these dates
Sow in early summer, six weeks after the last frost, and pinch the tips once to make the plants bush. Move them to their final position in autumn, twenty weeks after the last frost, so the roots settle before winter. Flowering starts the following April and runs six weeks.
Hardy to about -20C. Clubroot is a real risk because it is a brassica, so do not plant it where cabbages grew; rotate it around the garden as you would a vegetable.
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. Wallflowers are timed with planting out 20 weeks after it, and this page simply resolves those offsets against the frost date computed for Essen.
Hardiness is not the obstacle here. Essen is zone 8a, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.
This is a two-season crop, so the dates above describe a sowing in one year and a flowering in the next. The plant spends the winter in the ground as a small rosette, which is why the frost-free season in Essen does not limit it the way it would limit a tomato: it is not trying to finish before the cold arrives, it is trying to be well enough rooted to sit through it. Sowing too late is the real risk, because a plant that goes into winter undersized often fails to flower at all the following year.
Also in Essen
Other flowers to time
Growing wallflowers in Essen
When should I plant wallflowers in Essen?
Aim for 29 May - 26 Jun in an average year. If you would rather not gamble on the weather, wait until 7 Jun - 5 Jul - by then frost has finished in nine years out of ten.
When will wallflowers be ready to harvest in Essen?
Expect to start picking around 1 Apr - 31 May, based on 300 to 340 days to maturity from the planting date calculated for this location.
How much frost will wallflowers tolerate?
Hardy to about -20C. Clubroot is a real risk because it is a brassica, so do not plant it where cabbages grew; rotate it around the garden as you would a vegetable.