Flower · Brassicaceae
When to sow wallflowers
Grown for a scent that is closer to warm honey than to anything floral, filling a garden on a still April evening. Traditionally planted with tulips, and traditionally bought as bare-root bundles in autumn.
Plant out
20 weeks after
Counted from your last spring frost.
Sow direct
6 weeks after
Counted from your last spring frost.
Days to maturity
300-340
From sowing to a first picking.
Those weeks become real dates once you name a place.
Timing, in frost-relative terms
Seed packets rarely give calendar dates, because a date that suits one latitude is wrong at another. They give offsets from the last spring frost instead, and those offsets are what make wallflowers plantable anywhere.
- Plant out 20 weeks after the last frost.
- Sow direct 6 weeks after the last frost.
- Expect 300–340 days to maturity, counted from sowing.
- Hardy in USDA zones 5a–9a.
Getting the timing right
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.
Frost tolerance
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.
Classified as very-hardy, with damage expected below -20°C (-4°F)-4°F (-20°C).