Santa Rosa, CA planting zone & frost dates
Santa Rosa is in USDA hardiness zone 9b. The last spring frost usually comes around February 25 and the first fall frost around December 1, for a growing season of about 279 days.
Planting calendar for Santa Rosa
Dates are counted from the average last spring frost (February 25) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Dec 31 – Jan 14 Transplant outdoors: Mar 4 – Mar 11 |
| Peppers | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Mar 11 – Mar 18 |
| Eggplant | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Mar 11 – Mar 18 |
| Broccoli | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Jan 28 – Feb 11 |
| Cabbage | Start seeds indoors: Dec 17 – Dec 31 Transplant outdoors: Jan 28 – Feb 11 |
| Onions (sets) | Plant outdoors: Jan 28 – Feb 11 |
| Peas | Sow outdoors: Jan 14 – Jan 28 |
| Spinach | Sow outdoors: Jan 14 – Jan 28 |
| Lettuce | Sow outdoors: Jan 28 – Feb 11 |
| Carrots | Sow outdoors: Jan 28 – Feb 11 |
| Potatoes | Plant outdoors: Jan 28 – Feb 11 |
| Beans | Sow outdoors: Mar 4 – Mar 11 |
| Sweet corn | Sow outdoors: Mar 4 – Mar 11 |
| Cucumbers | Sow outdoors: Mar 4 – Mar 11 |
| Squash & zucchini | Sow outdoors: Mar 4 – Mar 11 |
| Basil | Start seeds indoors: Jan 14 – Jan 28 Transplant outdoors: Mar 4 – Mar 11 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 6 (8 weeks before the average first fall frost on Dec 1).
Useful for zone 9b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Shade cloth — for hot summers
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Jan 21 | Feb 25 | Mar 29 |
| First 32°F frost in fall is before | Dec 24 | Dec 1 | Nov 10 |
How to read it: in spring there is a 10% chance of a frost after March 29, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 10. A hard freeze (28°F) usually ends around January 20.
Hardiness zone by ZIP code in Santa Rosa
- 95401 zone 9a
- 95402 zone 9b
- 95403 zone 9a
- 95404 zone 9b
- 95405 zone 9a
- 95406 zone 9a
- 95407 zone 9a
- 95409 zone 9b
Nearby cities
- Rohnert Park zone 9a, last frost Feb 28
- Windsor zone 9a, last frost Mar 2
- Petaluma zone 9a, last frost Feb 28
- Healdsburg zone 9b, last frost Feb 15
- Agua Caliente zone 9b, last frost Mar 2
- Sonoma zone 9b, last frost Mar 2
- Novato zone 9b, last frost Jan 11
- Napa zone 9b, last frost Feb 12
Questions
What growing zone is Santa Rosa, CA?
Santa Rosa is in USDA Plant Hardiness Zone 9b (average extreme winter low 25°F to 30°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 9a.
When is the last frost in Santa Rosa?
The average last spring frost (32°F) in Santa Rosa is February 25. There is still a 10% chance of frost until March 29.
When can I plant tomatoes in Santa Rosa?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 4 – Mar 11. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Santa Rosa, CA (USC00047965), 1.7 km (1.1 mi) from the city center, elevation 51 m, based on 22 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.