Los Altos, CA planting zone & frost dates
Los Altos is in USDA hardiness zone 9b. The last spring frost usually comes around January 6 and the first fall frost around December 23, for a growing season of about 353 days.
Planting calendar for Los Altos
Dates are counted from the average last spring frost (January 6) 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 11 – Nov 25 Transplant outdoors: Jan 13 – Jan 20 |
| Peppers | Start seeds indoors: Oct 28 – Nov 11 Transplant outdoors: Jan 20 – Jan 27 |
| Eggplant | Start seeds indoors: Oct 28 – Nov 11 Transplant outdoors: Jan 20 – Jan 27 |
| Broccoli | Start seeds indoors: Oct 28 – Nov 11 Transplant outdoors: Dec 9 – Dec 23 |
| Cabbage | Start seeds indoors: Oct 28 – Nov 11 Transplant outdoors: Dec 9 – Dec 23 |
| Onions (sets) | Plant outdoors: Dec 9 – Dec 23 |
| Peas | Sow outdoors: Nov 25 – Dec 9 |
| Spinach | Sow outdoors: Nov 25 – Dec 9 |
| Lettuce | Sow outdoors: Dec 9 – Dec 23 |
| Carrots | Sow outdoors: Dec 9 – Dec 23 |
| Potatoes | Plant outdoors: Dec 9 – Dec 23 |
| Beans | Sow outdoors: Jan 13 – Jan 20 |
| Sweet corn | Sow outdoors: Jan 13 – Jan 20 |
| Cucumbers | Sow outdoors: Jan 13 – Jan 20 |
| Squash & zucchini | Sow outdoors: Jan 13 – Jan 20 |
| Basil | Start seeds indoors: Nov 25 – Dec 9 Transplant outdoors: Jan 13 – Jan 20 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Oct 28 (8 weeks before the average first fall frost on Dec 23).
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 16 | Jan 6 | Feb 4 |
| First 32°F frost in fall is before | Jan 16 | Dec 23 | Dec 3 |
How to read it: in spring there is a 10% chance of a frost after February 4, so that is a safe date for tender plants. In fall there is a 10% chance of frost before December 3. A hard freeze (28°F) usually ends around January 1.
Hardiness zone by ZIP code in Los Altos
- 94022 zone 9b
- 94023 zone 9b
- 94024 zone 9b
Nearby cities
- Mountain View zone 10a, last frost Jan 6
- Palo Alto zone 9b, last frost Feb 1
- Stanford zone 9b, last frost Feb 1
- Sunnyvale zone 10a, last frost Jan 6
- East Palo Alto zone 10a, last frost Feb 1
- Menlo Park zone 9b, last frost Feb 1
- Cupertino zone 9b, last frost Jan 6
- Saratoga zone 9b, last frost Feb 2
Questions
What growing zone is Los Altos, CA?
Los Altos 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 Los Altos?
The average last spring frost (32°F) in Los Altos is January 6. There is still a 10% chance of frost until February 4.
When can I plant tomatoes in Los Altos?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jan 13 – Jan 20. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Moffett Federal Airfield, CA (USW00023244), 6.3 km (3.9 mi) from the city center, elevation 12 m, based on 22 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.