Hercules, CA planting zone & frost dates
Hercules is in USDA hardiness zone 9b. The last spring frost usually comes around January 17 and the first fall frost around December 27, for a growing season of about 346 days.
Planting calendar for Hercules
Dates are counted from the average last spring frost (January 17) 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 22 – Dec 6 Transplant outdoors: Jan 24 – Jan 31 |
| Peppers | Start seeds indoors: Nov 8 – Nov 22 Transplant outdoors: Jan 31 – Feb 7 |
| Eggplant | Start seeds indoors: Nov 8 – Nov 22 Transplant outdoors: Jan 31 – Feb 7 |
| Broccoli | Start seeds indoors: Nov 8 – Nov 22 Transplant outdoors: Dec 20 – Jan 3 |
| Cabbage | Start seeds indoors: Nov 8 – Nov 22 Transplant outdoors: Dec 20 – Jan 3 |
| Onions (sets) | Plant outdoors: Dec 20 – Jan 3 |
| Peas | Sow outdoors: Dec 6 – Dec 20 |
| Spinach | Sow outdoors: Dec 6 – Dec 20 |
| Lettuce | Sow outdoors: Dec 20 – Jan 3 |
| Carrots | Sow outdoors: Dec 20 – Jan 3 |
| Potatoes | Plant outdoors: Dec 20 – Jan 3 |
| Beans | Sow outdoors: Jan 24 – Jan 31 |
| Sweet corn | Sow outdoors: Jan 24 – Jan 31 |
| Cucumbers | Sow outdoors: Jan 24 – Jan 31 |
| Squash & zucchini | Sow outdoors: Jan 24 – Jan 31 |
| Basil | Start seeds indoors: Dec 6 – Dec 20 Transplant outdoors: Jan 24 – Jan 31 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Nov 1 (8 weeks before the average first fall frost on Dec 27).
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 23 | Jan 17 | Mar 4 |
| First 32°F frost in fall is before | Feb 4 | Dec 27 | Dec 4 |
How to read it: in spring there is a 10% chance of a frost after March 4, so that is a safe date for tender plants. In fall there is a 10% chance of frost before December 4. A hard freeze (28°F) usually ends around January 5.
Hardiness zone by ZIP code in Hercules
- 94547 zone 9b
Nearby cities
- Pinole zone 9b
- El Sobrante zone 9b
- San Pablo zone 10a
- Vallejo zone 9b, last frost Jan 17
- Richmond zone 10a
- El Cerrito zone 10a
- Albany zone 10a
- Benicia zone 9b, last frost Feb 28
Questions
What growing zone is Hercules, CA?
Hercules 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 Hercules?
The average last spring frost (32°F) in Hercules is January 17. There is still a 10% chance of frost until March 4.
When can I plant tomatoes in Hercules?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jan 24 – Jan 31. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Vallejo, CA (USC00049219), 12.8 km (7.9 mi) from the city center, elevation 104 m, based on 7 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.