Riverside, CA planting zone & frost dates
Riverside is in USDA hardiness zone 10a. The last spring frost usually comes around January 9 and the first fall frost around December 25, for a growing season of about 353 days.
Planting calendar for Riverside
Dates are counted from the average last spring frost (January 9) 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 14 – Nov 28 Transplant outdoors: Jan 16 – Jan 23 |
| Peppers | Start seeds indoors: Oct 31 – Nov 14 Transplant outdoors: Jan 23 – Jan 30 |
| Eggplant | Start seeds indoors: Oct 31 – Nov 14 Transplant outdoors: Jan 23 – Jan 30 |
| Broccoli | Start seeds indoors: Oct 31 – Nov 14 Transplant outdoors: Dec 12 – Dec 26 |
| Cabbage | Start seeds indoors: Oct 31 – Nov 14 Transplant outdoors: Dec 12 – Dec 26 |
| Onions (sets) | Plant outdoors: Dec 12 – Dec 26 |
| Peas | Sow outdoors: Nov 28 – Dec 12 |
| Spinach | Sow outdoors: Nov 28 – Dec 12 |
| Lettuce | Sow outdoors: Dec 12 – Dec 26 |
| Carrots | Sow outdoors: Dec 12 – Dec 26 |
| Potatoes | Plant outdoors: Dec 12 – Dec 26 |
| Beans | Sow outdoors: Jan 16 – Jan 23 |
| Sweet corn | Sow outdoors: Jan 16 – Jan 23 |
| Cucumbers | Sow outdoors: Jan 16 – Jan 23 |
| Squash & zucchini | Sow outdoors: Jan 16 – Jan 23 |
| Basil | Start seeds indoors: Nov 28 – Dec 12 Transplant outdoors: Jan 16 – Jan 23 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 30 (8 weeks before the average first fall frost on Dec 25).
Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Dec 16 | Jan 9 | Feb 25 |
| First 32°F frost in fall is before | Jan 27 | Dec 25 | Dec 1 |
How to read it: in spring there is a 10% chance of a frost after February 25, so that is a safe date for tender plants. In fall there is a 10% chance of frost before December 1. A hard freeze (28°F) usually ends around December 31.
Hardiness zone by ZIP code in Riverside
- 92501 zone 10a
- 92502 zone 10a
- 92503 zone 10a
- 92504 zone 10a
- 92505 zone 10a
- 92506 zone 10a
- 92507 zone 10a
- 92508 zone 9b
- 92509 zone 10a
- 92513 zone 10a
- 92514 zone 10a
- 92516 zone 10a
- 92517 zone 10a
- 92519 zone 10a
- 92521 zone 10a
- 92522 zone 10a
Nearby cities
- Rubidoux zone 10a
- Woodcrest zone 9b, last frost Jan 9
- Pedley zone 10a
- Glen Avon zone 10a
- Grand Terrace zone 10a
- Bloomington zone 10a
- Jurupa Valley zone 10a
- Fontana zone 10a
Questions
What growing zone is Riverside, CA?
Riverside is in USDA Plant Hardiness Zone 10a (average extreme winter low 30°F to 35°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 9b.
When is the last frost in Riverside?
The average last spring frost (32°F) in Riverside is January 9. There is still a 10% chance of frost until February 25.
When can I plant tomatoes in Riverside?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jan 16 – Jan 23. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Riverside Fire Stn 3, CA (USC00047470), 0.8 km (0.5 mi) from the city center, elevation 256 m, based on 21 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.