Frost dates · USDA zone 9a
Frost dates for Santa Rosa, CA
Santa Rosa, CA sees its last 32 °F night of spring around February 25 and its first of fall around December 1 — a 279-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | Jan 21 | Dec 24 |
| Median — 1 year in 2 | Feb 25 | Dec 1 |
| 1 year in 10 | Mar 29 | Nov 10 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 279 days median, at least 244 in 9 years of 10, at least 319 days in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of Jan 20 and first of Dec 16.
Santa Rosa planting calendar, 2027
Every row runs from the median last frost (Feb 25) and median first frost (Dec 1) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Dec 3 | Jan 28 | May 18 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Feb 25 | Mar 27 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Feb 11 | Feb 11 | Mar 28 | 45 from sow |
| Genovese BasilGenovese | Jan 28 | Mar 11 | May 10 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Dec 31 | Mar 4 | May 18 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Dec 17 | Mar 11 | Jun 14 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Dec 31 | Mar 4 | May 18 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Dec 31 | Mar 4 | May 23 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Dec 31 | Mar 4 | May 23 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Feb 11 | Feb 11 | Apr 22 | 70 from sow |
| TomatilloToma Verde | Jan 14 | Mar 4 | May 13 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Jan 14 | Mar 4 | May 18 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Jan 14 | Mar 4 | May 23 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can Santa Rosa grow?
Each sauce, scheduled for a Santa Rosa container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Santa Rosa frost questions
When is the last frost in Santa Rosa, CA?
The median last 32 °F freeze at SANTA ROSA, CA is February 25: half of years see a later one. One year in ten, a freeze still comes after March 29; nine years in ten, it comes after January 21. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Santa Rosa, CA?
The median first 32 °F freeze of fall is December 1. One year in ten it arrives before November 10; nine years in ten, before December 24.
How long is the growing season in Santa Rosa, CA?
279 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 244 days; one year in ten, at least 319 days.
What growing zone is Santa Rosa, CA?
USDA hardiness zone 9a, per the 2023 USDA Plant Hardiness Zone Map for ZIP 95405. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in Santa Rosa, CA?
Start Roma VF (determinate paste) seeds indoors around Jan 14 and transplant around Mar 4, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for Mar 29. First ripe fruit lands around May 18.
When should I plant peppers in Santa Rosa, CA?
Sow jalapeño indoors on a heat mat around Dec 31; transplant no earlier than Mar 4, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around May 18.
Nearby in California
- Rohnert Parklast frost Feb 28
- Petalumalast frost Feb 28
- Napalast frost Feb 12
- Novatolast frost Jan 11
- Vallejolast frost Mar 5
- San Rafaellast frost Jan 11
All California frost dates → · How frost-date math drives a sowing calendar →