Rohnert Park, CA planting zone & frost dates
Rohnert Park is in USDA hardiness zone 9a. The last spring frost usually comes around February 28 and the first fall frost around November 25, for a growing season of about 271 days.
Planting calendar for Rohnert Park
Dates are counted from the average last spring frost (February 28) 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: Jan 3 – Jan 17 Transplant outdoors: Mar 7 – Mar 14 |
| Peppers | Start seeds indoors: Dec 20 – Jan 3 Transplant outdoors: Mar 14 – Mar 21 |
| Eggplant | Start seeds indoors: Dec 20 – Jan 3 Transplant outdoors: Mar 14 – Mar 21 |
| Broccoli | Start seeds indoors: Dec 20 – Jan 3 Transplant outdoors: Jan 31 – Feb 14 |
| Cabbage | Start seeds indoors: Dec 20 – Jan 3 Transplant outdoors: Jan 31 – Feb 14 |
| Onions (sets) | Plant outdoors: Jan 31 – Feb 14 |
| Peas | Sow outdoors: Jan 17 – Jan 31 |
| Spinach | Sow outdoors: Jan 17 – Jan 31 |
| Lettuce | Sow outdoors: Jan 31 – Feb 14 |
| Carrots | Sow outdoors: Jan 31 – Feb 14 |
| Potatoes | Plant outdoors: Jan 31 – Feb 14 |
| Beans | Sow outdoors: Mar 7 – Mar 14 |
| Sweet corn | Sow outdoors: Mar 7 – Mar 14 |
| Cucumbers | Sow outdoors: Mar 7 – Mar 14 |
| Squash & zucchini | Sow outdoors: Mar 7 – Mar 14 |
| Basil | Start seeds indoors: Jan 17 – Jan 31 Transplant outdoors: Mar 7 – Mar 14 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 30 (8 weeks before the average first fall frost on Nov 25).
Useful for zone 9a 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 24 | Feb 28 | Apr 6 |
| First 32°F frost in fall is before | Dec 16 | Nov 25 | Nov 9 |
How to read it: in spring there is a 10% chance of a frost after April 6, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 9. A hard freeze (28°F) usually ends around January 17.
Hardiness zone by ZIP code in Rohnert Park
- 94926 zone 9a
- 94927 zone 9a
- 94928 zone 9a
Nearby cities
- Santa Rosa zone 9b, last frost Feb 25
- Petaluma zone 9a, last frost Feb 28
- Agua Caliente zone 9b, last frost Mar 2
- Windsor zone 9a, last frost Mar 2
- Sonoma zone 9b, last frost Mar 2
- Novato zone 9b, last frost Jan 11
- Healdsburg zone 9b, last frost Feb 15
- San Anselmo zone 9b, last frost Jan 16
Questions
What growing zone is Rohnert Park, CA?
Rohnert Park is in USDA Plant Hardiness Zone 9a (average extreme winter low 20°F to 25°F), according to the USDA 2023 map.
When is the last frost in Rohnert Park?
The average last spring frost (32°F) in Rohnert Park is February 28. There is still a 10% chance of frost until April 6.
When can I plant tomatoes in Rohnert Park?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Mar 7 – Mar 14. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Petaluma Ap, CA (USC00046826), 12.2 km (7.6 mi) from the city center, elevation 6 m, based on 26 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.