Planting zone for Grass Valley, CA
Grass Valley, CA is in USDA zones 9a to 9b across its 2 ZIP codes. The median last spring frost is April 14 and the first fall frost November 20.
Grass Valley on the zone map
Outlined: its 2 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoomNot the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.
9a 1 ZIP 9b 1 ZIP
Frost forecast — next 7 nights
live from the National Weather ServiceLoading the forecast for Grass Valley, CA…
Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.
Frost dates in Grass Valley, CA
A hard freeze (28 °F) usually ends around March 17 and returns around December 8.
From the NOAA station Nevada City, CA, elevation 2,782 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.
When to plant vegetables in Grass Valley
Counted from the median last spring frost (Apr 14) and first fall frost (Nov 20) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.
When spring arrived in 2026
In 2026, spring leaf-out near 95945 came on Jan 24 — 19 days earlier than the 1991–2020 average (Feb 12).
Feb 122026
Jan 24
The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).
Soil in Grass Valley, CA
The center of ZIP 95945 is mapped as Alluvial land, clayey: built-over ground without natural soil data. Garden soil here is usually imported or disturbed — test before you plant.
Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 95945; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in Grass Valley, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Nevada City, CA (4 mi away); precipitation: Nevada City 1.7 Sse, CA (3 mi away). Daylight is calculated from latitude.
ZIP codes in Grass Valley
Questions about Grass Valley
What planting zone is Grass Valley, CA?
Grass Valley, CA is in USDA hardiness zones 9a to 9b on the 2023 map (9a: 20 to 25 °F; 9b: 25 to 30 °F).
When is the last frost in Grass Valley, CA?
The median last spring frost is April 14 and the median first fall frost is November 20 (NOAA 1991–2020 normals, Nevada City station).
When can I plant a garden in Grass Valley, CA?
Cool-season crops like peas and spinach go in around Mar 3 – Mar 24; tomatoes, peppers, beans and squash after about Apr 21, once frost risk has passed.
What kind of onions grow in Grass Valley, CA?
Intermediate onions: the longest day is 14 h 55 min, so day-neutral types bulb best; long-day varieties may not bulb fully.
How much rain and snow does Grass Valley, CA get?
About 49 inches of precipitation a year (NOAA 1991–2020 normals).