Castro Valley, CA planting zone & frost dates
Castro Valley is in USDA hardiness zone 10a. Frost is rare here: in most years temperatures do not drop to 32°F.
Useful for zone 10a gardens
- Drip irrigation kit — saves water in long, hot seasons
- Shade cloth — protects plants from midday sun
- Soil moisture meter
- Plants for zone 10
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Hardiness zone by ZIP code in Castro Valley
- 94546 zone 9b
- 94552 zone 9b
Nearby cities
- Cherryland zone 10a
- Hayward zone 10a
- Ashland zone 10a
- Fairview zone 9b
- San Lorenzo zone 10a
- San Leandro zone 10a, last frost Jan 7
- Union City zone 9b, last frost Jan 7
- San Ramon zone 9b, last frost Feb 15
Questions
What growing zone is Castro Valley, CA?
Castro Valley is in USDA Plant Hardiness Zone 10a (average extreme winter low 30°F to 35°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 9b.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Hayward Air Terminal, CA (USW00093228), 5.1 km (3.2 mi) from the city center, elevation 13 m, based on 21 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.