Clearlake, CA planting zone & frost dates
Clearlake is in USDA hardiness zone 9a. The last spring frost usually comes around April 10 and the first fall frost around November 6, for a growing season of about 209 days.
Planting calendar for Clearlake
Dates are counted from the average last spring frost (April 10) 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: Feb 13 – Feb 27 Transplant outdoors: Apr 17 – Apr 24 |
| Peppers | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Apr 24 – May 1 |
| Eggplant | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Apr 24 – May 1 |
| Broccoli | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Mar 13 – Mar 27 |
| Cabbage | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Mar 13 – Mar 27 |
| Onions (sets) | Plant outdoors: Mar 13 – Mar 27 |
| Peas | Sow outdoors: Feb 27 – Mar 13 |
| Spinach | Sow outdoors: Feb 27 – Mar 13 |
| Lettuce | Sow outdoors: Mar 13 – Mar 27 |
| Carrots | Sow outdoors: Mar 13 – Mar 27 |
| Potatoes | Plant outdoors: Mar 13 – Mar 27 |
| Beans | Sow outdoors: Apr 17 – Apr 24 |
| Sweet corn | Sow outdoors: Apr 17 – Apr 24 |
| Cucumbers | Sow outdoors: Apr 17 – Apr 24 |
| Squash & zucchini | Sow outdoors: Apr 17 – Apr 24 |
| Basil | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: Apr 17 – Apr 24 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 11 (8 weeks before the average first fall frost on Nov 6).
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 | Mar 24 | Apr 10 | Apr 30 |
| First 32°F frost in fall is before | Nov 20 | Nov 6 | Oct 24 |
How to read it: in spring there is a 10% chance of a frost after April 30, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 24. A hard freeze (28°F) usually ends around March 14.
Hardiness zone by ZIP code in Clearlake
- 95422 zone 9a
Nearby cities
- Healdsburg zone 9b, last frost Feb 15
- Windsor zone 9a, last frost Mar 2
- Santa Rosa zone 9b, last frost Feb 25
- Ukiah zone 9a, last frost Mar 19
- Rohnert Park zone 9a, last frost Feb 28
- Agua Caliente zone 9b, last frost Mar 2
- Sonoma zone 9b, last frost Mar 2
- Petaluma zone 9a, last frost Feb 28
Questions
What growing zone is Clearlake, CA?
Clearlake 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 Clearlake?
The average last spring frost (32°F) in Clearlake is April 10. There is still a 10% chance of frost until April 30.
When can I plant tomatoes in Clearlake?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 17 – Apr 24. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Clearlake 4 Se, CA (USC00041806), 6.4 km (4.0 mi) from the city center, elevation 411 m, based on 12 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.