Napa, CA planting zone & frost dates
Napa is in USDA hardiness zone 9b. The last spring frost usually comes around February 12 and the first fall frost around December 4, for a growing season of about 299 days.
Planting calendar for Napa
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 9 (8 weeks before the average first fall frost on Dec 4).
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 | Jan 3 | Feb 12 | Mar 13 |
| First 32°F frost in fall is before | Jan 4 | Dec 4 | Nov 15 |
How to read it: in spring there is a 10% chance of a frost after March 13, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 15. A hard freeze (28°F) usually ends around January 11.
Hardiness zone by ZIP code in Napa
- 94558 zone 9b
- 94559 zone 9b
- 94581 zone 9b
Nearby cities
- American Canyon zone 9b, last frost Mar 5
- Sonoma zone 9b, last frost Mar 2
- Vallejo zone 9b, last frost Jan 17
- Agua Caliente zone 9b, last frost Mar 2
- Fairfield zone 9b, last frost Jan 15
- Suisun zone 9b, last frost Jan 15
- Benicia zone 9b, last frost Feb 28
- Hercules zone 9b, last frost Jan 17
Questions
What growing zone is Napa, CA?
Napa 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 Napa?
The average last spring frost (32°F) in Napa is February 12. There is still a 10% chance of frost until March 13.
When can I plant tomatoes in Napa?
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 Napa State Hospital, CA (USC00046074), 2.8 km (1.7 mi) from the city center, elevation 11 m, based on 28 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.