Porterville, CA planting zone & frost dates
Porterville is in USDA hardiness zone 9b. The last spring frost usually comes around January 20 and the first fall frost around December 13, for a growing season of about 330 days.
Planting calendar for Porterville
Dates are counted from the average last spring frost (January 20) 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: Nov 25 – Dec 9 Transplant outdoors: Jan 27 – Feb 3 |
| Peppers | Start seeds indoors: Nov 11 – Nov 25 Transplant outdoors: Feb 3 – Feb 10 |
| Eggplant | Start seeds indoors: Nov 11 – Nov 25 Transplant outdoors: Feb 3 – Feb 10 |
| Broccoli | Start seeds indoors: Nov 11 – Nov 25 Transplant outdoors: Dec 23 – Jan 6 |
| Cabbage | Start seeds indoors: Nov 11 – Nov 25 Transplant outdoors: Dec 23 – Jan 6 |
| Onions (sets) | Plant outdoors: Dec 23 – Jan 6 |
| Peas | Sow outdoors: Dec 9 – Dec 23 |
| Spinach | Sow outdoors: Dec 9 – Dec 23 |
| Lettuce | Sow outdoors: Dec 23 – Jan 6 |
| Carrots | Sow outdoors: Dec 23 – Jan 6 |
| Potatoes | Plant outdoors: Dec 23 – Jan 6 |
| Beans | Sow outdoors: Jan 27 – Feb 3 |
| Sweet corn | Sow outdoors: Jan 27 – Feb 3 |
| Cucumbers | Sow outdoors: Jan 27 – Feb 3 |
| Squash & zucchini | Sow outdoors: Jan 27 – Feb 3 |
| Basil | Start seeds indoors: Dec 9 – Dec 23 Transplant outdoors: Jan 27 – Feb 3 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 18 (8 weeks before the average first fall frost on Dec 13).
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 | Dec 25 | Jan 20 | Feb 22 |
| First 32°F frost in fall is before | Jan 6 | Dec 13 | Nov 26 |
How to read it: in spring there is a 10% chance of a frost after February 22, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 26. A hard freeze (28°F) usually ends around December 31.
Hardiness zone by ZIP code in Porterville
- 93257 zone 9b
- 93258 zone 9b
Nearby cities
Questions
What growing zone is Porterville, CA?
Porterville is in USDA Plant Hardiness Zone 9b (average extreme winter low 25°F to 30°F), according to the USDA 2023 map.
When is the last frost in Porterville?
The average last spring frost (32°F) in Porterville is January 20. There is still a 10% chance of frost until February 22.
When can I plant tomatoes in Porterville?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jan 27 – Feb 3. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Porterville, CA (USC00047077), 0.4 km (0.2 mi) from the city center, elevation 120 m, based on 11 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.