California
Planting zones in Sierra County, California
This county spans USDA zones 6b to 9a, so there is no single zone for Sierra County and anyone who gives you one is rounding. 38% of its ZIP codes are zone 6b; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Sierra County, California as a whole. Hardiness zones and freeze dates are published per ZIP code, so yours is exact — enter it and this page will tell you your zone, which NOAA station it comes from and how far away that station is.
The growing season in Sierra County is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives September 10 – October 30 across the 5 NOAA stations serving this county .
Your next season already has a date
The first job of it is 🧅 Green Onions, start indoors, around March 3 – April 16 — counted back from a last spring freeze of April 28 – June 11 here.
These are ranges across the whole county. The ZIP lookup above gives the dates from your own nearest station instead.
All 5 stations agreeAt least one station
Every one of the 5 NOAA stations serving this county counts June 11 – September 10 as growing season (91 days). Widening to any single station gives April 28 – October 30 (185 days).
That is a 94-day difference inside one county — which is why this page gives ranges rather than a single planting date. The ZIP lookup above resolves it to one station.
Which zone you are in depends where you are
Sierra County covers 5 hardiness zones. A guide that gives the county one zone has picked whichever is largest and rounded everyone else into it — fine for the 38% in zone 6b and wrong for the other 62%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 6b | 3 | 38% | |
| 8b | 2 | 25% | |
| 7a | 1 | 13% | |
| 8a | 1 | 13% | |
| 9a | 1 | 13% |
Zones are published per ZIP code, so yours is exact even though the county's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Across the 5 NOAA stations serving this county. These are medians — half of years freeze later than the date shown — so treat the later end of each range as the cautious one.
The growing season runs 91–178 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 78.7–86.4 °F in June–August. Summer rain over the same months runs 1.2–1.4" across those 4 stations, against the rough inch a week — about 13 inches over the same 92 days — that a vegetable garden is usually reckoned to want. The middle station covers about 11% of it, so a summer garden here is watered rather than rained on. The inches are NOAA's published normals; the inch a week is a rule of thumb, and it takes no account of a 82 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in Sierra County
Zones are published per ZIP code, not per county, so this is the exact answer rather than the county's average. The station column is the nearest one to that ZIP code's centroid and how far away it is — the same figure the tools use, shown here so you can see which ZIP codes are well covered and which are reaching.
| ZIP code | USDA zone | Nearest NOAA station | Distance |
|---|---|---|---|
| 95910 | 8b | Downieville, CA | 11.2 km |
| 95936 | 8a | Downieville, CA | 4.7 km |
| 95944 | 8b | Downieville, CA | 3.5 km |
| 95960 | 9a | Strawberry Valley, CA | 15.6 km |
| 96118 | 6b | Verdi 2W, CA | 23.0 km |
| 96124 | 6b | Portola, CA | 18.5 km |
| 96125 | 7a | Bowman Dam, CA | 18.3 km |
| 96126 | 6b | Bowman Dam, CA | 24.1 km |
ZIP-code positions are area centroids, so a large rural ZIP code's listed distance is measured from the middle of its area rather than from any particular address in it.
When to start seeds in Sierra County
Every date below is anchored on the last spring freeze at each station and reported as a range across all 5 of them, because no one station speaks for the county.
| Crop | Job | When | Offset |
|---|---|---|---|
| 🧅 Green Onions | Start indoors | March 3 – April 16 | 8 wk before |
| 🌶️ Peppers | Start indoors | March 3 – April 16 | 8 wk before |
| 🥦 Broccoli | Start indoors | March 17 – April 30 | 6 wk before |
| 🥬 Cabbage | Start indoors | March 17 – April 30 | 6 wk before |
| 🥬 Collards | Start indoors | March 17 – April 30 | 6 wk before |
| 🥬 Kale | Start indoors | March 17 – April 30 | 6 wk before |
| 🥬 Leaf Lettuce | Start indoors | March 17 – April 30 | 6 wk before |
| 🫛 Peas | Direct sow | March 17 – April 30 | 6 wk before |
| 🥬 Spinach | Direct sow | March 17 – April 30 | 6 wk before |
| 🍠 Sweet Potato | Start indoors | March 17 – April 30 | 6 wk before |
| 🍅 Tomatoes | Start indoors | March 17 – April 30 | 6 wk before |
| 🥬 Bok Choy | Start indoors | March 24 – May 7 | 5 wk before |
| 🥬 Kohlrabi | Start indoors | March 24 – May 7 | 5 wk before |
| 🥬 Swiss Chard | Start indoors | March 24 – May 7 | 5 wk before |
| 🥬 Arugula | Direct sow | March 31 – May 14 | 4 wk before |
| 🥬 Baby Salad Greens | Direct sow | March 31 – May 14 | 4 wk before |
| 🥕 Beets | Direct sow | March 31 – May 14 | 4 wk before |
| 🧅 Green Onions | Direct sow | March 31 – May 14 | 4 wk before |
| 🥬 Mustard Greens | Direct sow | March 31 – May 14 | 4 wk before |
| 🌶️ Okra | Start indoors | March 31 – May 14 | 4 wk before |
| 🌱 Radishes | Direct sow | March 31 – May 14 | 4 wk before |
| 🥔 Turnips | Direct sow | March 31 – May 14 | 4 wk before |
| 🥬 Cabbage | Set out | April 7 – May 21 | 3 wk before |
| 🥕 Carrots | Direct sow | April 7 – May 21 | 3 wk before |
| 🥬 Collards | Direct sow | April 7 – May 21 | 3 wk before |
| 🥬 Collards | Set out | April 7 – May 21 | 3 wk before |
| 🥒 Cucumbers | Start indoors | April 7 – May 21 | 3 wk before |
| 🧅 Green Onions | Set out | April 7 – May 21 | 3 wk before |
| 🥬 Kale | Direct sow | April 7 – May 21 | 3 wk before |
| 🥬 Kale | Set out | April 7 – May 21 | 3 wk before |
| 🥬 Kohlrabi | Direct sow | April 7 – May 21 | 3 wk before |
| 🥬 Kohlrabi | Set out | April 7 – May 21 | 3 wk before |
| 🥬 Leaf Lettuce | Direct sow | April 7 – May 21 | 3 wk before |
| 🎃 Pumpkins | Start indoors | April 7 – May 21 | 3 wk before |
| 🎃 Summer Squash | Start indoors | April 7 – May 21 | 3 wk before |
| 🎃 Winter Squash | Start indoors | April 7 – May 21 | 3 wk before |
| 🥒 Zucchini | Start indoors | April 7 – May 21 | 3 wk before |
| 🥬 Bok Choy | Direct sow | April 14 – May 28 | 2 wk before |
| 🥬 Bok Choy | Set out | April 14 – May 28 | 2 wk before |
| 🥦 Broccoli | Set out | April 14 – May 28 | 2 wk before |
| 🌿 Cilantro | Direct sow | April 14 – May 28 | 2 wk before |
| 🥬 Leaf Lettuce | Set out | April 14 – May 28 | 2 wk before |
| 🥬 Swiss Chard | Direct sow | April 14 – May 28 | 2 wk before |
| 🥬 Swiss Chard | Set out | April 14 – May 28 | 2 wk before |
| 🌿 Dill | Direct sow | April 21 – June 4 | 1 wk before |
| 🫘 Bush Beans | Direct sow | May 5 – June 18 | 1 wk after |
| 🥒 Cucumbers | Set out | May 5 – June 18 | 1 wk after |
| 🎃 Pumpkins | Direct sow | May 5 – June 18 | 1 wk after |
| 🎃 Pumpkins | Set out | May 5 – June 18 | 1 wk after |
| 🎃 Summer Squash | Direct sow | May 5 – June 18 | 1 wk after |
| 🎃 Summer Squash | Set out | May 5 – June 18 | 1 wk after |
| 🌽 Sweet Corn | Direct sow | May 5 – June 18 | 1 wk after |
| 🍅 Tomatoes | Set out | May 5 – June 18 | 1 wk after |
| 🎃 Winter Squash | Direct sow | May 5 – June 18 | 1 wk after |
| 🎃 Winter Squash | Set out | May 5 – June 18 | 1 wk after |
| 🥒 Zucchini | Direct sow | May 5 – June 18 | 1 wk after |
| 🥒 Zucchini | Set out | May 5 – June 18 | 1 wk after |
| 🥒 Cucumbers | Direct sow | May 12 – June 25 | 2 wk after |
| 🌶️ Okra | Direct sow | May 12 – June 25 | 2 wk after |
| 🌶️ Okra | Set out | May 12 – June 25 | 2 wk after |
| 🌶️ Peppers | Set out | May 12 – June 25 | 2 wk after |
| 🫘 Southern Peas | Direct sow | May 12 – June 25 | 2 wk after |
| 🍠 Sweet Potato | Set out | May 12 – June 25 | 2 wk after |
Offsets are published guidance; the dates they land on are computed from measured NOAA normals. The seed-starting tool does this for your own ZIP code and counts the days.
What survives the winter changes across Sierra County
Zone 7a carries 58 of 74 perennial edibles; zone 9a carries 46. The best number is not always the warmest zone — the count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat, not to cold.
Hardiness ranges are a judgement, published by growers rather than measured; the zone they are compared against is measured. On a warm-end verdict, check with your local extension service — a coastal zone 8 and an inland zone 8 are not the same summer.
Cautious — shortens the seasonMedian across stationsOptimistic
- Last spring freeze
- Plan to July 2 to be careful. Median April 28 – June 11 across 5 stations; April 13 is the optimistic end.
- First fall freeze
- Plan to August 22 to be careful. Median September 10 – October 30 across 5 stations; November 14 is the optimistic end.
NOAA publishes these as probabilities, not averages — the middle figure is a median, so half of years fall either side of it. The cautious end is the 10% tail: in roughly nine years in ten the freeze falls on the safe side of it.
The 5 stations behind these numbers
All 5 NOAA stations whose normals this page quotes, spanning about 39 km north to south. Every one is named with its identifier in the station list below — this page does not single one out, because no one station speaks for a whole county.
A relative sketch, not a map with a projection: longitude is adjusted for latitude so the shape is not stretched, and there is no basemap. For the one station nearest a specific address, with its real distance, use the ZIP lookup above.
These are the stations this county's ZIP codes actually cite as nearest — not a claim that each one sits inside its boundary, since a rural ZIP legitimately reaches over it. Every figure above comes from them, and each is named so you can check it.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Bowman Dam, CA | USC00041018 | May 12 | October 29 | 167 days |
| Downieville, CA | USC00042500 | April 28 | October 25 | 178 days |
| Portola, CA | USC00047085 | June 11 | September 10 | 91 days |
| Strawberry Valley, CA | USC00048606 | May 4 | October 30 | 174 days |
| Verdi 2W, CA | USC00049298 | May 9 | October 17 | 156 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Your own ZIP
Work out your own dates
This page describes a whole county. Every tool below answers for one ZIP code, which is the grain the underlying data is published at.
Other places to compare
Sierra County sits in California. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.
More of California
- Glenn County, CA 9a–9b
- Del Norte County, CA 8a, 9b
- Humboldt County, CA 9a–9b
- Mendocino County, CA 9a–10a
- Siskiyou County, CA 6b, 7b, 8a, 8b
- Calaveras County, CA 8b–9b
- Lassen County, CA 6a–7a
- Plumas County, CA 6b–8a
- Lake County, CA 8b–9b
- Tehama County, CA 7a, 7b, 9a, 9b
- Tuolumne County, CA 6a, 6b, 7b, 8a, 8b, 9a, 9b
- Trinity County, CA 7b, 8b, 9a
Gear
If you want to act on this
Each link opens an Amazon search rather than a product we picked. We have not tested these and do not rank them — the search is the honest version, and you choose.
- Row cover and frost clothThe season here closes at the first fall freeze dated above — a cover buys back some of those days at the end.
- MulchFor the perennials nearest their cold limit in zone 6b, where an insulated crown is what decides whether they come back.
As an Amazon Associate we earn from qualifying purchases. That costs you nothing extra, and it buys no influence over anything on this site: the dates come from NOAA normals and the zones from the USDA, and no product affects either.
Sources
Where these numbers come from
Hardiness zones are the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. Freeze dates and growing-season lengths are NOAA 1991–2020 Climate Normals, taken per station and cited above by name and NOAA ID.
County boundaries come from the Census ZCTA-to-county relation, which is what places each ZIP code — and which treats parishes, boroughs and census areas as county equivalents. No station is chosen to represent this county: every range above is taken across all of them and the count is stated, because picking one would be a judgement dressed as a measurement.