Flower · Iridaceae
When to sow freesias
Grown almost entirely for the scent, which is stronger in the older narrow-flowered forms than in the showy modern ones. A cool-season plant that stops flowering in real heat.
Hardy in USDA zones
9a to 11a
Winter cold sets the limit here, not the calendar.
Frost tolerance
Tender
How much cold the plant itself will take.
Those weeks become real dates once you name a place.
Timing, in frost-relative terms
Nothing about a standing crop is sown to a calendar. Once planted, freesias stay in the ground for years, so the question is not when to sow but whether your winter is survivable and your planting window is open. Both answers come from your frost dates.
- Hardy in USDA zones 9a–11a.
Getting the timing right
In frost-free gardens plant corms in autumn for late-winter flowers. Where there is frost, plant after the last one for early-summer flowers, or grow them in pots started in autumn and kept somewhere cool and bright. Freesias need cool nights below about 13C to initiate flowers at all, which is why a warm greenhouse produces leaves and nothing else.
Frost tolerance
Killed at about -3C. The limiting factor is heat rather than cold: the corms need a warm dry dormancy but the growing plant wants cool conditions, so hot-summer climates flower them in winter and spring only.
Classified as tender, with damage expected below -3°C (26.6°F)26.6°F (-3°C).