Alpine, CA planting zone & frost dates
Alpine is in USDA hardiness zone 9b. The last spring frost usually comes around February 12 and the first fall frost around December 24, for a growing season of about 317 days.
Planting calendar for Alpine
Dates are counted from the average last spring frost (February 12) 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 18 – Jan 1 Transplant outdoors: Feb 19 – Feb 26 |
| Peppers | Start seeds indoors: Dec 4 – Dec 18 Transplant outdoors: Feb 26 – Mar 5 |
| Eggplant | Start seeds indoors: Dec 4 – Dec 18 Transplant outdoors: Feb 26 – Mar 5 |
| Broccoli | Start seeds indoors: Dec 4 – Dec 18 Transplant outdoors: Jan 15 – Jan 29 |
| Cabbage | Start seeds indoors: Dec 4 – Dec 18 Transplant outdoors: Jan 15 – Jan 29 |
| Onions (sets) | Plant outdoors: Jan 15 – Jan 29 |
| Peas | Sow outdoors: Jan 1 – Jan 15 |
| Spinach | Sow outdoors: Jan 1 – Jan 15 |
| Lettuce | Sow outdoors: Jan 15 – Jan 29 |
| Carrots | Sow outdoors: Jan 15 – Jan 29 |
| Potatoes | Plant outdoors: Jan 15 – Jan 29 |
| Beans | Sow outdoors: Feb 19 – Feb 26 |
| Sweet corn | Sow outdoors: Feb 19 – Feb 26 |
| Cucumbers | Sow outdoors: Feb 19 – Feb 26 |
| Squash & zucchini | Sow outdoors: Feb 19 – Feb 26 |
| Basil | Start seeds indoors: Jan 1 – Jan 15 Transplant outdoors: Feb 19 – Feb 26 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 29 (8 weeks before the average first fall frost on Dec 24).
Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Dec 29 | Feb 12 | Mar 20 |
| First 32°F frost in fall is before | Feb 3 | Dec 24 | Dec 2 |
How to read it: in spring there is a 10% chance of a frost after March 20, so that is a safe date for tender plants. In fall there is a 10% chance of frost before December 2. A hard freeze (28°F) usually ends around January 22.
Hardiness zone by ZIP code in Alpine
- 91901 zone 9b
- 91903 zone 9b
Nearby cities
- Lakeside zone 10a, last frost Jan 6
- Winter Gardens zone 10a, last frost Jan 6
- San Diego Country Estates zone 9b, last frost Mar 4
- Bostonia zone 10a, last frost Jan 6
- Rancho San Diego zone 10b, last frost Jan 6
- El Cajon zone 10a, last frost Jan 6
- Santee zone 10a, last frost Jan 6
- Casa de Oro-Mount Helix zone 10b, last frost Jan 6
Questions
What growing zone is Alpine, CA?
Alpine 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 Alpine?
The average last spring frost (32°F) in Alpine is February 12. There is still a 10% chance of frost until March 20.
When can I plant tomatoes in Alpine?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Feb 19 – Feb 26. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Alpine, CA (USC00040136), 1.0 km (0.6 mi) from the city center, elevation 517 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.