Simi Valley, CA planting zone & frost dates
Simi Valley is in USDA hardiness zone 10a. The last spring frost usually comes around January 24 and the first fall frost around December 15, for a growing season of about 329 days.
Planting calendar for Simi Valley
Dates are counted from the average last spring frost (January 24) 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 29 – Dec 13 Transplant outdoors: Jan 31 – Feb 7 |
| Peppers | Start seeds indoors: Nov 15 – Nov 29 Transplant outdoors: Feb 7 – Feb 14 |
| Eggplant | Start seeds indoors: Nov 15 – Nov 29 Transplant outdoors: Feb 7 – Feb 14 |
| Broccoli | Start seeds indoors: Nov 15 – Nov 29 Transplant outdoors: Dec 27 – Jan 10 |
| Cabbage | Start seeds indoors: Nov 15 – Nov 29 Transplant outdoors: Dec 27 – Jan 10 |
| Onions (sets) | Plant outdoors: Dec 27 – Jan 10 |
| Peas | Sow outdoors: Dec 13 – Dec 27 |
| Spinach | Sow outdoors: Dec 13 – Dec 27 |
| Lettuce | Sow outdoors: Dec 27 – Jan 10 |
| Carrots | Sow outdoors: Dec 27 – Jan 10 |
| Potatoes | Plant outdoors: Dec 27 – Jan 10 |
| Beans | Sow outdoors: Jan 31 – Feb 7 |
| Sweet corn | Sow outdoors: Jan 31 – Feb 7 |
| Cucumbers | Sow outdoors: Jan 31 – Feb 7 |
| Squash & zucchini | Sow outdoors: Jan 31 – Feb 7 |
| Basil | Start seeds indoors: Dec 13 – Dec 27 Transplant outdoors: Jan 31 – Feb 7 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 20 (8 weeks before the average first fall frost on Dec 15).
Useful for zone 10a 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 21 | Jan 24 | Mar 5 |
| First 32°F frost in fall is before | Jan 26 | Dec 15 | Nov 27 |
How to read it: in spring there is a 10% chance of a frost after March 5, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 27. A hard freeze (28°F) usually ends around December 31.
Hardiness zone by ZIP code in Simi Valley
- 93062 zone 10a
- 93063 zone 10a
- 93065 zone 10a
- 93094 zone 10a
- 93099 zone 10a
Nearby cities
- Oak Park zone 10b, last frost Jan 24
- Moorpark zone 10a
- Thousand Oaks zone 10a
- Agoura Hills zone 10a, last frost Jan 24
- Agoura zone 10b, last frost Jan 24
- Fillmore zone 10a
- Stevenson Ranch zone 10a
- Malibu zone 11a, last frost Jan 24
Questions
What growing zone is Simi Valley, CA?
Simi Valley is in USDA Plant Hardiness Zone 10a (average extreme winter low 30°F to 35°F), according to the USDA 2023 map.
When is the last frost in Simi Valley?
The average last spring frost (32°F) in Simi Valley is January 24. There is still a 10% chance of frost until March 5.
When can I plant tomatoes in Simi Valley?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jan 31 – Feb 7. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Woodland Hills Pierce College, CA (USC00049785), 21.4 km (13.3 mi) from the city center, elevation 241 m, based on 24 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.