Rosemary in Zone 9a & 9b
Salvia rosmarinus
When to plant rosemary in zone 9b
Zones 9a and 9b share the same average frost dates in our data, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. Rosemary needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Dec 7–Dec 14 |
|---|---|
| Direct sow / transplant outside | Mar 1–Mar 8 |
| Estimated harvest | May 30–Jun 6 (~90 days after transplanting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-4 ft.
Rosemary is a woody Mediterranean shrub, not a tender annual herb. Treat it more like a small perennial landscape plant than something you replant every spring. In the right climate, one plant can keep producing for years.
How rosemary fits zone 9's season
Zone 9b's frost-free window runs about 293 days, from February 15 to December 5. Rosemary needs about 90 days from transplant to first harvest.
Good companions
- Cabbage: Rosemary's scent is reputed to deter cabbage moths, the same role thyme and sage play, though rosemary itself hasn't been specifically tested the way thyme and sage have — treat this as garden tradition rather than a directly measured result.
Where to buy rosemary seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing rosemary" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 9b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Rosemary in USDA zone 9b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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