California planting calendar

When to plant rosemary in California — sow, transplant & harvest dates

California is mostly USDA zone 9b (range 5a-11a). Dates below are derived from rosemary's frost tolerance and California's frost window — not generic national averages.

Rosemary planting timetable for California

Stage	When in California	Anchor
Start seeds indoors (spring crop)	early December (December 7)	10 weeks before the last frost (mid-February (coast) to late April (interior))
Transplant outside (spring crop)	early March (March 1)	14 days after the last frost (mid-February (coast) to late April (interior))
Spring-crop harvest	late May onward, before peak summer heat	90-day crop — finishes before mid-summer
Plant the fall crop	early August (August 3) — once the worst heat breaks	~104 days before the first fall frost (mid-November (coast) to mid-October (interior))
Fall-crop harvest	early November into early winter	90-day crop — often the more productive of the two

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why California's climate shifts the rosemary dates

California's long hot summer shuts down fruit set, so locals run two short crops — a spring planting and a fall planting — around a deliberate mid-summer pause, instead of one long northern-style season. California packs more climate diversity than almost any state — alpine mountains, Mediterranean coast, Central Valley farmland, and desert. Coastal and valley areas grow year-round.

Start seeds indoors 10–12 weeks before the last frost; germination is slow and erratic (14–21 days at 18–21 °C / 65–70 °F) with low viability, so propagation by stem cuttings is preferred by most Extension services. Transplant outdoors after the last frost once soil has warmed — rosemary is perennial only in USDA zones 7–10 (established plants survive to about −12 °C / 10 °F); in zones 6 and colder treat as a tender annual or overwinter potted plants indoors before the first autumn frost. Tip harvests of stem ends begin around 80–100 days from transplant.

Frost-risk note

A light frost in the high Sierra Nevada (zone 5a-6a) can clip an early spring planting; the bigger risk is mid-summer heat sterilising flowers.

Regional variation within California

the southern coast and Imperial Valley (zone 11a) can start the spring crop weeks earlier and may garden almost year-round; the high Sierra Nevada (zone 5a-6a) runs a shorter, more northern-style single season.

Los Angeles — USDA zone 10b
San Francisco — USDA zone 10b
Sacramento — USDA zone 9b
San Diego — USDA zone 10b
Fresno — USDA zone 9b

What else to plant in California around then

Pair the spring slot with other heat-lovers (peppers, squash, beans); use the cool October–February window for greens and brassicas.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 18–21 °C (65–70 °F).
Spacing: 18–36 inches (45–90 cm) between plants.
Days to harvest: ~90 days from planting out.

Frequently asked questions

When is the best time to plant rosemary in California?

In California (mostly USDA zone 9b), sow rosemary indoors around early December, set the spring crop out early March, harvest before peak summer heat, then plant a second crop early August for an autumn harvest. Avoid mid-summer. Rosemary are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

What USDA zone is California?

Most of California sits in USDA hardiness zone 9b, with the state spanning roughly 5a-11a from the high Sierra Nevada (zone 5a-6a) to the southern coast and Imperial Valley (zone 11a). The last spring frost averages mid-February (coast) to late April (interior) and the first fall frost mid-November (coast) to mid-October (interior).

Can you grow rosemary in California?

Yes. California's dominant zone 9b supports rosemary — the key is timing. Rosemary are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

Does the planting date change across California?

What else can I plant in California around the same time?

Pair the spring slot with other heat-lovers (peppers, squash, beans); use the cool October–February window for greens and brassicas.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.