USDA zone 6b in California
USDA plant hardiness zone 6b covers 14 locations across California (average annual extreme minimum −5 to 0 °F): Alturas, CA, Benton, CA, Chilcoot-Vinton, CA, Floriston, CA, Lake, CA, Lake, CA, and 8 more. Average last spring frost across this group ranges March 16 (Silver) to June 11 (Chilcoot-Vinton), and growing seasons run 91–249 days (Chilcoot-Vinton to Silver) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every California location's own frost dates; the printable planting calendar uses Lake, this group's median-season location.
- USDA zone
- 6b−5 to 0 °F
- Last frost range
- Mar 16–Jun 11avg, 32°F
- First frost range
- Sep 10–Nov 26avg, 32°F
- Growing season range
- 91–249days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Alturas | Likely, Madeline | Alturas Muni Ap | Jun 3 | Sep 12 | 97 |
| Benton | Mono | Lee Vining | May 23 | Oct 9 | 139 |
| Chilcoot-Vinton | Beckwourth, Portola, Sierraville, Sattley, Sierra Brooks | Portola | Jun 11 | Sep 10 | 91 |
| Floriston | — | Verdi 2w | May 9 | Oct 17 | 156 |
| Lake * | Cedarville, Eagleville | Cedarville | May 15 | Oct 1 | 137 |
| Lake | Fort Bidwell, New Pine Creek | Ft Bidwell | May 26 | Oct 1 | 127 |
| Litchfield | Madeline | Susanville 2sw | May 16 | Oct 8 | 143 |
| Mount Hebron | — | Lava Beds Nat Mon | Jun 6 | Sep 28 | 113 |
| Newell | Bonanza, Malin, Merrill | Tulelake | Jun 6 | Sep 14 | 97 |
| Silver | — | Three Rivers Edison Ph 1 | Mar 16 | Nov 26 | 249 |
| Strawberry | — | Hetch Hetchy | Apr 16 | Nov 12 | 208 |
| Tahoma | — | Glenbrook | Jun 5 | Oct 9 | 126 |
| Truckee | Incline, Kings Beach | Tahoe City | Jun 9 | Sep 25 | 108 |
| Walker | Bear Valley | Topaz Lake | May 12 | Oct 6 | 145 |
* Lake is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Lake, representative)
Computed from Lake's average frost dates — the median-season location in this Californiazone 6b group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Mar 20 – Apr 3 | May 22 – May 29 | Jul 21 – Aug 10 | — | matures comfortably |
| Pepper | Very tender | Mar 6 – Mar 20 | May 29 – Jun 5 | Jul 28 – Aug 27 | — | matures comfortably |
| Cucumber | Tender | Apr 17 – Apr 24 | May 22 – May 29 | Jul 11 – Jul 31 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 22 – May 29 | Jul 6 – Jul 21 | — | matures comfortably |
| Bush bean | Tender | — | May 22 – May 29 | Jul 11 – Jul 21 | Aug 2 – Aug 12 | matures comfortably |
| Sweet corn | Tender | — | May 15 – May 29 | Jul 14 – Aug 13 | — | matures comfortably |
| Basil | Very tender | Apr 3 – Apr 17 | May 22 – May 29 | Jun 21 – Jul 6 | — | matures comfortably |
| Lettuce | Half-hardy | Apr 3 – Apr 17 | Apr 17 – May 1 | Jun 1 – Jun 16 | Jul 19 – Aug 3 | matures comfortably |
| Pea | Hardy | — | Apr 3 – Apr 17 | May 28 – Jun 12 | Jul 9 – Jul 24 | matures comfortably |
| Spinach | Hardy | — | Apr 3 – Apr 17 | May 13 – May 23 | Jul 29 – Aug 8 | matures comfortably |
| Carrot | Half-hardy | — | Apr 24 – May 1 | Jun 23 – Jul 13 | Jun 29 – Jul 19 | matures comfortably |
| Broccoli | Half-hardy | Mar 20 – Apr 3 | Apr 17 – May 1 | Jun 11 – Jul 1 | Jul 4 – Jul 24 | matures comfortably |
Which crops fit this growing season
Using Lake's own 137-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Lake)
From NOAA's 1991–2020 Climate Normals at station USC00041614. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Jun 3 | Jun 19 | Sep 20 | Oct 3 | 107 |
| 32°F (freeze) | May 15 | Jun 6 | Oct 1 | Oct 16 | 137 |
| 28°F | Apr 27 | May 16 | Oct 13 | Oct 28 | 167 |
| 24°F | Apr 12 | Apr 29 | Oct 25 | Nov 10 | 195 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 14 locations is 2,142; Lake's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,548 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,651 | cool-season crops (brassicas, greens) |
Hardiness zone 6b in California
Zone 6b means an average annual extreme minimum winter temperature of about −5 to 0 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. California spans 12 hardiness zones in this dataset — see all California locations for the full range, including zones5b, 6a, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b, 11a.
Explore zone 6b in other states at zone 6b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 6b mean in California?
- Zone 6b means an average annual extreme minimum winter temperature of −5 to 0 °F — the standard USDA measure of which perennials survive winter. 14 locations in California fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in California's zone 6b is the growing season longest?
- Silver runs the longest season on this page at about 249 days; Chilcoot-Vinton is shortest at about 91 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in California's zone 6b?
- Using Lake's frost dates (this page's median-season location): start seeds indoors about Mar 20 – Apr 3, then transplant outside about May 22 – May 29. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in California's zone 6b have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 14 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.