California
Planting zones in Glenn County, California
This county spans USDA zones 9a to 9b, so there is no single zone for Glenn County and anyone who gives you one is rounding. 86% of its ZIP codes are zone 9b; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Glenn 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 Glenn County is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives November 13 – December 7 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 January 7 – December 31 — counted back from a last spring freeze of January 29 – April 5 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 April 5 – November 13 as growing season (222 days). Widening to any single station gives January 29 – December 7 (312 days).
That is a 90-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
Glenn County covers 2 hardiness zones. A guide that gives the county one zone has picked whichever is largest and rounded everyone else into it — fine for the 86% in zone 9b and wrong for the other 14%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 9b | 6 | 86% | |
| 9a | 1 | 14% |
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 220–317 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 92–93.2 °F in June–August. That is past the point where tomato and pepper pollen fails and cool-season greens bolt, so in this county heat decides as much as frost does. Summer rain over the same months runs 0.4–0.8" across those 5 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 4% 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 93 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in Glenn 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 |
|---|---|---|---|
| 95913 | 9b | Orland, CA | 13.0 km |
| 95920 | 9b | Oroville Muni AP, CA | 27.7 km |
| 95939 | 9a | Stony Gorge Rsvr, CA | 7.2 km |
| 95943 | 9b | Chico Univ Farm, CA | 22.4 km |
| 95951 | 9b | Chico Univ Farm, CA | 16.1 km |
| 95963 | 9b | Orland, CA | 8.9 km |
| 95988 | 9b | Willows 6 W, CA | 3.2 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 Glenn 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 |
|---|---|---|---|
| 🥬 Arugula | Direct sow | January 1 – March 8 | 4 wk before |
| 🥬 Baby Salad Greens | Direct sow | January 1 – March 8 | 4 wk before |
| 🥕 Beets | Direct sow | January 1 – March 8 | 4 wk before |
| 🧅 Green Onions | Direct sow | January 1 – March 8 | 4 wk before |
| 🥬 Mustard Greens | Direct sow | January 1 – March 8 | 4 wk before |
| 🌶️ Okra | Start indoors | January 1 – March 8 | 4 wk before |
| 🌱 Radishes | Direct sow | January 1 – March 8 | 4 wk before |
| 🥔 Turnips | Direct sow | January 1 – March 8 | 4 wk before |
| 🧅 Green Onions | Start indoors | January 7 – December 31 | 8 wk before |
| 🌶️ Peppers | Start indoors | January 7 – December 31 | 8 wk before |
| 🥬 Cabbage | Set out | January 8 – March 15 | 3 wk before |
| 🥕 Carrots | Direct sow | January 8 – March 15 | 3 wk before |
| 🥬 Collards | Direct sow | January 8 – March 15 | 3 wk before |
| 🥬 Collards | Set out | January 8 – March 15 | 3 wk before |
| 🥒 Cucumbers | Start indoors | January 8 – March 15 | 3 wk before |
| 🧅 Green Onions | Set out | January 8 – March 15 | 3 wk before |
| 🥬 Kale | Direct sow | January 8 – March 15 | 3 wk before |
| 🥬 Kale | Set out | January 8 – March 15 | 3 wk before |
| 🥬 Kohlrabi | Direct sow | January 8 – March 15 | 3 wk before |
| 🥬 Kohlrabi | Set out | January 8 – March 15 | 3 wk before |
| 🥬 Leaf Lettuce | Direct sow | January 8 – March 15 | 3 wk before |
| 🎃 Pumpkins | Start indoors | January 8 – March 15 | 3 wk before |
| 🎃 Summer Squash | Start indoors | January 8 – March 15 | 3 wk before |
| 🎃 Winter Squash | Start indoors | January 8 – March 15 | 3 wk before |
| 🥒 Zucchini | Start indoors | January 8 – March 15 | 3 wk before |
| 🥦 Broccoli | Start indoors | January 10 – December 18 | 6 wk before |
| 🥬 Cabbage | Start indoors | January 10 – December 18 | 6 wk before |
| 🥬 Collards | Start indoors | January 10 – December 18 | 6 wk before |
| 🥬 Kale | Start indoors | January 10 – December 18 | 6 wk before |
| 🥬 Leaf Lettuce | Start indoors | January 10 – December 18 | 6 wk before |
| 🫛 Peas | Direct sow | January 10 – December 18 | 6 wk before |
| 🥬 Spinach | Direct sow | January 10 – December 18 | 6 wk before |
| 🍠 Sweet Potato | Start indoors | January 10 – December 18 | 6 wk before |
| 🍅 Tomatoes | Start indoors | January 10 – December 18 | 6 wk before |
| 🥬 Bok Choy | Direct sow | January 15 – March 22 | 2 wk before |
| 🥬 Bok Choy | Set out | January 15 – March 22 | 2 wk before |
| 🥦 Broccoli | Set out | January 15 – March 22 | 2 wk before |
| 🌿 Cilantro | Direct sow | January 15 – March 22 | 2 wk before |
| 🥬 Leaf Lettuce | Set out | January 15 – March 22 | 2 wk before |
| 🥬 Swiss Chard | Direct sow | January 15 – March 22 | 2 wk before |
| 🥬 Swiss Chard | Set out | January 15 – March 22 | 2 wk before |
| 🥬 Bok Choy | Start indoors | January 17 – December 25 | 5 wk before |
| 🥬 Kohlrabi | Start indoors | January 17 – December 25 | 5 wk before |
| 🥬 Swiss Chard | Start indoors | January 17 – December 25 | 5 wk before |
| 🌿 Dill | Direct sow | January 22 – March 29 | 1 wk before |
| 🫘 Bush Beans | Direct sow | February 5 – April 12 | 1 wk after |
| 🥒 Cucumbers | Set out | February 5 – April 12 | 1 wk after |
| 🎃 Pumpkins | Direct sow | February 5 – April 12 | 1 wk after |
| 🎃 Pumpkins | Set out | February 5 – April 12 | 1 wk after |
| 🎃 Summer Squash | Direct sow | February 5 – April 12 | 1 wk after |
| 🎃 Summer Squash | Set out | February 5 – April 12 | 1 wk after |
| 🌽 Sweet Corn | Direct sow | February 5 – April 12 | 1 wk after |
| 🍅 Tomatoes | Set out | February 5 – April 12 | 1 wk after |
| 🎃 Winter Squash | Direct sow | February 5 – April 12 | 1 wk after |
| 🎃 Winter Squash | Set out | February 5 – April 12 | 1 wk after |
| 🥒 Zucchini | Direct sow | February 5 – April 12 | 1 wk after |
| 🥒 Zucchini | Set out | February 5 – April 12 | 1 wk after |
| 🥒 Cucumbers | Direct sow | February 12 – April 19 | 2 wk after |
| 🌶️ Okra | Direct sow | February 12 – April 19 | 2 wk after |
| 🌶️ Okra | Set out | February 12 – April 19 | 2 wk after |
| 🌶️ Peppers | Set out | February 12 – April 19 | 2 wk after |
| 🫘 Southern Peas | Direct sow | February 12 – April 19 | 2 wk after |
| 🍠 Sweet Potato | Set out | February 12 – April 19 | 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 Glenn County
Zone 9a carries 46 of 74 perennial edibles; zone 9b carries 40. 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.
At least one station here freezes across the new year, which puts the two ends of a spread on opposite sides of the calendar. Drawing it would produce a bar spanning almost the whole year and meaning nothing, so none is drawn.
The 5 stations behind these numbers
All 5 NOAA stations whose normals this page quotes, spanning about 28 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 |
|---|---|---|---|---|
| Chico Univ Farm, CA | USC00041715 | March 4 | November 17 | 257 days |
| Orland, CA | USC00046506 | February 25 | December 2 | 279 days |
| Oroville Muni AP, CA | USW00093210 | January 29 | December 7 | 317 days |
| Stony Gorge Rsvr, CA | USC00048587 | April 5 | November 13 | 220 days |
| Willows 6 W, CA | USC00049699 | February 21 | December 6 | 289 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
Glenn 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
- 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
- Modoc County, CA 6b–7a
Counties with the same zones — 9a–9b
Matched on the exact zone set, not a dominant zone, so the winter answer on these pages really is the same one as here.
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.
- Shade clothSummer highs here average 93 °F, at or above the 90 °F point where lettuce and spinach bolt and tomato pollen fails.
- 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.
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.