USDA Zone 11 is frost-free year-round, with average winter lows of 40 to 50°F. There is no last spring frost and no first autumn frost to plan around, so Zone 11 gardeners plant by heat and by the wet and dry seasons instead of by frost dates. The heat and humidity that let tropical crops grow all year make cool-season crops much harder. Frost dates here are zone averages and vary by microclimate, elevation and year — check your local extension service for guidance for your exact spot.
Rosemary is the tough, woody, evergreen herb of roast potatoes, lamb and focaccia, and it is one of the best perennial herbs for Zone 11 — with one condition. It is a Mediterranean plant that wants sun, wind and sharp drainage, and it will die fast in wet, heavy soil. Give it drainage and it will live for years, growing into a fragrant shrub you pick from all year.
Zone 11 at a glance
USDA Zone 11 is frost-free year-round, with average winter lows of 40 to 50°F. Plant by the season: the coolest, driest months for cool-season crops, and the cooler part of the year for the best fruit set on heat lovers.
| Detail | Zone 11 guidance |
|---|---|
| Average winter low | 40 to 50°F |
| Last spring frost | None — frost-free year-round |
| First autumn frost | None — frost-free year-round |
| Days to germination | 14–28 days |
| Days to maturity | 90–120 days |
| Sowing | start indoors |
| Best planting window | Year-round; best October to February so roots establish before the wettest weather |
| Harvest | 90–120 days after sowing/transplanting |
| Sun | full sun |
| Soil pH | 6.0–7.0 |
| Spacing | 24–36 inches |
| Water needs | low |
| Cold tolerance | tender |
When to plant rosemary in Zone 11
Plant rosemary any time of year in Zone 11, but the best time is October to February, in the cooler, drier months, so roots can establish before the wettest weather. Seeds germinate in 14–28 days and plants take 90–120 days to reach a first light harvest, though rosemary is really a long-term plant: it is far more productive in its second year and beyond. Zone 11 is frost-free, so there is no last frost date to work back from — plant by the dry season instead, and check your local extension service for your area.
Work by the season rather than by frost dates: the planting calendar hub gives the Zone 11 picture month by month, and the month guide for October in Zone 11 shows what else is happening at planting time. The harvest date calculator can turn your sowing date into a harvest window.
Starting rosemary in Zone 11
Rosemary is started indoors from seed or, far more reliably, from cuttings and nursery plants. Seed germinates slowly and patchily in 14–28 days, so most Zone 11 gardeners buy a plant or take a cutting: strip the lower leaves from a 4-inch stem, push it into gritty compost, and keep it moist until it roots in a few weeks. Space plants 24–36 inches apart — a rosemary bush can grow several feet wide over the years — and harden indoor-started plants off for a week before they go out.
Soil, spacing, sun and water
Rosemary grows best in full sun, in soil with a pH of 6.0–7.0, spaced 24–36 inches apart. Rosemary needs full sun and very sharp drainage. In Zone 11 this is the make-or-break factor: heavy rain on clay soil rots the roots fast. Dig in coarse grit or perlite, plant on a mound or in a raised bed, and use gravel mulch rather than bark, which holds moisture against the crown. Water young plants until established, then water only in long dry spells. Overwatering kills more rosemary in the tropics than any pest. Rosemary needs low water: water deeply when the top inch or two of soil feels dry, rather than sprinkling lightly every day, and water at the base in the morning so leaves dry before night. Mulch helps hold moisture.
Companion planting
Good companions for rosemary include tomatoes, peppers, marigolds, cabbage. The companion planting finder can suggest combinations for your whole garden. Rotate crops each year and avoid planting where the same family (Lamiaceae) grew last year. A related crop to plan alongside is thyme, which shares the Zone 11 calendar, so the two guides work well together.
Pests and problems
The common pests and problems to watch for with rosemary are aphids, spider mites, whiteflies. Aphids gather on young tips and wash off with water. Spider mites appear in hot, dry weather, so keep plants watered at the base and avoid wetting the leaves. Whiteflies are present year-round in Zone 11's warmth. The real killer is root rot from wet soil: if a plant yellows and wilts despite wet soil, the roots are rotting and there is no cure, so prevention through drainage is everything. Inspect plants regularly, especially leaf undersides, and act early: hand-pick larger pests, wash aphids off with water, and remove badly affected leaves. Healthy plants in the right soil and spacing resist pests better than stressed ones. If you are unsure what you are looking at, the pest identifier helper can narrow it down.
Harvest and storage
Harvest rosemary once plants are established, about 90–120 days after sowing, by snipping sprigs as needed — never take more than a third of the plant at once. Pick in the morning, when the oils are strongest, and use fresh or dried: rosemary dries very well and keeps its flavour for months in a jar. Prune lightly after flowering to keep plants compact, but never cut into old woody stems, which may not regrow. In frost-free Zone 11, rosemary is evergreen and you can pick fresh sprigs all year.
Frequently asked questions
When should I plant rosemary in Zone 11?
Any time of year, but October to February is best, so roots establish before the wettest weather. Zone 11 is frost-free year-round. Check your local extension service for your area.
How long does rosemary take to grow in Zone 11?
Seeds germinate in 14–28 days and plants take 90–120 days to reach a first light harvest. It is a long-term perennial, far more productive from its second year.
Why is my rosemary dying in Zone 11?
Almost always wet soil or overwatering. Rosemary needs sharp drainage and low water once established — use grit, a raised bed or a mound, and water sparingly.
What soil and spacing does rosemary need in Zone 11?
Full sun, sharply drained soil with a pH of 6.0–7.0, spaced 24–36 inches apart, with low water and gravel mulch rather than bark.