Herb · Lamiaceae
When to plant rosemary
Evergreen, drought-proof once established, and picked all year round. Dies of wet feet in winter far more often than of cold.
First worthwhile crop
Year 1
After planting, not after sowing.
Hardy in USDA zones
7a to 10a
Winter cold sets the limit here, not the calendar.
Frost tolerance
Hardy
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, rosemary 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.
- Expect a first worthwhile crop in year 1 after planting.
- Hardy in USDA zones 7a–10a.
Getting the timing right
Plant out after the last frost so the roots establish through a full growing season. Cuttings root readily in early summer, which is a faster and more reliable route than seed - rosemary seed germinates poorly and slowly.
Frost tolerance
Hardy to about -15C in free-draining soil, and considerably less in heavy wet ground. Drainage matters more than any temperature figure here.
Classified as hardy, with damage expected below -15°C (5°F)5°F (-15°C).