Discovery Bay, CA planting zone & frost dates
Discovery Bay is in USDA hardiness zone 9b. The last spring frost usually comes around January 19 and the first fall frost around December 10, for a growing season of about 330 days.
Planting calendar for Discovery Bay
Dates are counted from the average last spring frost (January 19) 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 24 – Dec 8 Transplant outdoors: Jan 26 – Feb 2 |
| Peppers | Start seeds indoors: Nov 10 – Nov 24 Transplant outdoors: Feb 2 – Feb 9 |
| Eggplant | Start seeds indoors: Nov 10 – Nov 24 Transplant outdoors: Feb 2 – Feb 9 |
| Broccoli | Start seeds indoors: Nov 10 – Nov 24 Transplant outdoors: Dec 22 – Jan 5 |
| Cabbage | Start seeds indoors: Nov 10 – Nov 24 Transplant outdoors: Dec 22 – Jan 5 |
| Onions (sets) | Plant outdoors: Dec 22 – Jan 5 |
| Peas | Sow outdoors: Dec 8 – Dec 22 |
| Spinach | Sow outdoors: Dec 8 – Dec 22 |
| Lettuce | Sow outdoors: Dec 22 – Jan 5 |
| Carrots | Sow outdoors: Dec 22 – Jan 5 |
| Potatoes | Plant outdoors: Dec 22 – Jan 5 |
| Beans | Sow outdoors: Jan 26 – Feb 2 |
| Sweet corn | Sow outdoors: Jan 26 – Feb 2 |
| Cucumbers | Sow outdoors: Jan 26 – Feb 2 |
| Squash & zucchini | Sow outdoors: Jan 26 – Feb 2 |
| Basil | Start seeds indoors: Dec 8 – Dec 22 Transplant outdoors: Jan 26 – Feb 2 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 15 (8 weeks before the average first fall frost on Dec 10).
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 25 | Jan 19 | Feb 17 |
| First 32°F frost in fall is before | Jan 7 | Dec 10 | Nov 26 |
How to read it: in spring there is a 10% chance of a frost after February 17, so that is a safe date for tender plants. In fall there is a 10% chance of frost before November 26. A hard freeze (28°F) usually ends around January 1.
Hardiness zone by ZIP code in Discovery Bay
- 94505 zone 9b
Nearby cities
Questions
What growing zone is Discovery Bay, CA?
Discovery Bay 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 Discovery Bay?
The average last spring frost (32°F) in Discovery Bay is January 19. There is still a 10% chance of frost until February 17.
When can I plant tomatoes in Discovery Bay?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jan 26 – Feb 2. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Tracy Pumping Plt, CA (USC00049001), 12.6 km (7.8 mi) from the city center, elevation 19 m, based on 25 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.