State guide
Planting zones in Arizona
Arizona spans USDA zones 5b to 10a across its 415 ZIP codes, so there is no single zone for the state and anyone who gives you one is rounding. 36% of its ZIP codes are zone 9b; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Arizona 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.
Which zone you are in depends where you are
Arizona covers 10 hardiness zones. A guide that gives the state one zone has picked whichever is largest and rounded everyone else into it — which is fine for the 36% in zone 9b and wrong for the other 64%. Here is the actual split, by ZIP code.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 9b | 150 | 36% | |
| 9a | 60 | 14% | |
| 8b | 50 | 12% | |
| 7a | 44 | 11% | |
| 10a | 42 | 10% | |
| 6b | 26 | 6% | |
| 8a | 25 | 6% | |
| 7b | 12 | 3% | |
| 6a | 5 | 1% | |
| 5b | 1 | 0% |
Zones are published per ZIP code, so yours is exact even though the state's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Those are the earliest and latest medians among the 172 stations in Arizona with an ordinary freeze window — not an average, and not one station standing in for the rest. Half of years freeze later than a station's own median.
3 of this state's 175 stations are left out of that range, and saying so matters more than the range itself. 1 record no freeze at any probability, so they have no date to contribute. 2 sit where the freeze window crosses New Year, so their "first" freeze precedes their "last" and folding them in would be arithmetic on dates that do not sit in order. They are counted, not averaged away.
Your growing season
NOAA publishes a growing-season length for each station, and across the 175 stations in Arizona it runs 81–365 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 71–110 °F , reaching the 90 °F point where cool-season crops bolt and tomato and pepper pollen fails — so midsummer sowings of lettuce and its relatives are worth holding in the hotter parts of the state.
The ends of each range, named
A range with no station behind it cannot be checked, and Arizona has too many stations to table them all. So every figure above is reported here with the station standing at each end of it, by name and NOAA ID. No station on this page represents Arizona — these are its edges, which is a different claim.
| Measure | Earliest / lowest | Station | Latest / highest | Station |
|---|---|---|---|---|
| Last spring freeze | January 4 | Bullhead City, AZ USC00021050 | June 23 | Flagstaff 4 SW, AZ USC00023009 |
| First fall freeze | September 15 | Flagstaff 4 SW, AZ USC00023009 | December 29 | Willow Beach, AZ USC00029376 |
| Growing season | 81 days | Flagstaff 4 SW, AZ USC00023009 | 365 days | Phoenix Sky Harbor INTL AP, AZ USW00023183 |
| Mean summer high | 71 °F | Sunrise Mtn, AZ USC00028326 | 110 °F | Willow Beach, AZ USC00029376 |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
When to start seeds in Arizona
Every spring job for 63 crop dates, counted from this state's own last spring freeze. Each is a range across all 172 stations — the earliest and latest that job falls anywhere in Arizona — because no one station speaks for a whole state. The ranges are wide on purpose: that width is the state.
| Crop | Job | When | Offset |
|---|---|---|---|
| Arugula | Direct sow | January 1 – December 31 | 4 weeks before |
| Baby Salad Greens | Direct sow | January 1 – December 31 | 4 weeks before |
| Beets | Direct sow | January 1 – December 31 | 4 weeks before |
| Bok Choy | Start indoors | January 1 – December 31 | 5 weeks before |
| Bok Choy | Direct sow | January 1 – December 31 | 2 weeks before |
| Bok Choy | Set out | January 1 – December 31 | 2 weeks before |
| Broccoli | Set out | January 1 – December 31 | 2 weeks before |
| Cilantro | Direct sow | January 1 – December 31 | 2 weeks before |
| Dill | Direct sow | January 1 – December 31 | 1 week before |
| Green Onions | Start indoors | January 1 – December 31 | 8 weeks before |
| Green Onions | Direct sow | January 1 – December 31 | 4 weeks before |
| Kohlrabi | Start indoors | January 1 – December 31 | 5 weeks before |
| Leaf Lettuce | Set out | January 1 – December 31 | 2 weeks before |
| Mustard Greens | Direct sow | January 1 – December 31 | 4 weeks before |
| Okra | Start indoors | January 1 – December 31 | 4 weeks before |
| Peppers | Start indoors | January 1 – December 31 | 8 weeks before |
| Radishes | Direct sow | January 1 – December 31 | 4 weeks before |
| Swiss Chard | Start indoors | January 1 – December 31 | 5 weeks before |
| Swiss Chard | Direct sow | January 1 – December 31 | 2 weeks before |
| Swiss Chard | Set out | January 1 – December 31 | 2 weeks before |
| Turnips | Direct sow | January 1 – December 31 | 4 weeks before |
| Broccoli | Start indoors | January 2 – December 31 | 6 weeks before |
| Cabbage | Start indoors | January 2 – December 31 | 6 weeks before |
| Cabbage | Set out | January 2 – December 31 | 3 weeks before |
| Carrots | Direct sow | January 2 – December 31 | 3 weeks before |
| Collards | Start indoors | January 2 – December 31 | 6 weeks before |
| Collards | Direct sow | January 2 – December 31 | 3 weeks before |
| Collards | Set out | January 2 – December 31 | 3 weeks before |
| Cucumbers | Start indoors | January 2 – December 31 | 3 weeks before |
| Green Onions | Set out | January 2 – December 31 | 3 weeks before |
| Kale | Start indoors | January 2 – December 31 | 6 weeks before |
| Kale | Direct sow | January 2 – December 31 | 3 weeks before |
| Kale | Set out | January 2 – December 31 | 3 weeks before |
| Kohlrabi | Direct sow | January 2 – December 31 | 3 weeks before |
| Kohlrabi | Set out | January 2 – December 31 | 3 weeks before |
| Leaf Lettuce | Start indoors | January 2 – December 31 | 6 weeks before |
| Leaf Lettuce | Direct sow | January 2 – December 31 | 3 weeks before |
| Peas | Direct sow | January 2 – December 31 | 6 weeks before |
| Pumpkins | Start indoors | January 2 – December 31 | 3 weeks before |
| Spinach | Direct sow | January 2 – December 31 | 6 weeks before |
| Summer Squash | Start indoors | January 2 – December 31 | 3 weeks before |
| Sweet Potato | Start indoors | January 2 – December 31 | 6 weeks before |
| Tomatoes | Start indoors | January 2 – December 31 | 6 weeks before |
| Winter Squash | Start indoors | January 2 – December 31 | 3 weeks before |
| Zucchini | Start indoors | January 2 – December 31 | 3 weeks before |
| Bush Beans | Direct sow | January 11 – June 30 | 1 week after |
| Cucumbers | Set out | January 11 – June 30 | 1 week after |
| Pumpkins | Direct sow | January 11 – June 30 | 1 week after |
| Pumpkins | Set out | January 11 – June 30 | 1 week after |
| Summer Squash | Direct sow | January 11 – June 30 | 1 week after |
| Summer Squash | Set out | January 11 – June 30 | 1 week after |
| Sweet Corn | Direct sow | January 11 – June 30 | 1 week after |
| Tomatoes | Set out | January 11 – June 30 | 1 week after |
| Winter Squash | Direct sow | January 11 – June 30 | 1 week after |
| Winter Squash | Set out | January 11 – June 30 | 1 week after |
| Zucchini | Direct sow | January 11 – June 30 | 1 week after |
| Zucchini | Set out | January 11 – June 30 | 1 week after |
| Cucumbers | Direct sow | January 18 – July 7 | 2 weeks after |
| Okra | Direct sow | January 18 – July 7 | 2 weeks after |
| Okra | Set out | January 18 – July 7 | 2 weeks after |
| Peppers | Set out | January 18 – July 7 | 2 weeks after |
| Southern Peas | Direct sow | January 18 – July 7 | 2 weeks after |
| Sweet Potato | Set out | January 18 – July 7 | 2 weeks after |
The week offsets are conventional extension guidance and vary by variety; the freeze dates they are counted from are measured. For a single date rather than a range, run when do I start my seeds? with your own ZIP code.
What survives the winter changes across Arizona
Of 74 perennial fruits, nuts, berries, vegetables and herbs, 58 come through the winter in zone 7a and only 25 in zone 10a. Winter hardiness runs on the zone alone, so each row below is exact for the ZIP codes in it.
| Zone | ZIPs | Survive | Fail for being too warm |
|---|---|---|---|
| 5b | 1 | 48 of 74 | 0 |
| 6a | 5 | 51 of 74 | 0 |
| 6b | 26 | 51 of 74 | 0 |
| 7a | 44 | 58 of 74 | 1 |
| 7b | 12 | 56 of 74 | 3 |
| 8a | 25 | 57 of 74 | 8 |
| 8b | 50 | 54 of 74 | 11 |
| 9a | 60 | 46 of 74 | 25 |
| 9b | 150 | 40 of 74 | 32 |
| 10a | 42 | 25 of 74 | 49 |
The best zone in Arizona is 7a, which is not its mildest — 10a is. The count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat rather than to cold. Most temperate fruit needs a documented number of hours below about 45 °F to break dormancy and set a crop, so an apple fails in a winter that is too warm; currants and rhubarb cook in the heat that comes with it. See the full list with reasons.
Your own ZIP
Work out your own dates
Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.
- What survives my winter?
Runs on the hardiness zone, so it answers exactly for your ZIP code rather than for Arizona as a whole — 74 perennial fruits, berries, vegetables and herbs.
- When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
- When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
- What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.
Metro areas in Arizona
7 metro areas here have its own page, with the freeze dates from every station serving it, a spring calendar built from those stations, and every ZIP code in it listed with that ZIP code's exact zone and nearest station.
- Phoenix-Mesa-Chandler, AZ Zones 9a–10a
- Tucson, AZ Zones 8b–9b
- Prescott Valley-Prescott, AZ Zones 7a–9b
- Flagstaff, AZ Zones 5b–7b
- Lake Havasu City-Kingman, AZ Zones 7b–10a
- Sierra Vista-Douglas, AZ Zones 8a–8b
- Yuma, AZ Zones 9a–10a
Counties in Arizona
6 countys here have its own page, listing every ZIP code in it with that ZIP code's exact zone and nearest station. These are the smaller places outside the metro areas above — where most of Arizona's ZIP codes actually are.
- Apache County, AZ Zones 6a–7a
- Navajo County, AZ Zones 6b–7b
- Gila County, AZ Zones 7a, 8a, 8b, 9a
- Graham County, AZ Zones 8b–9a
- La Paz County, AZ Zones 9a–9b
- Santa Cruz County, AZ Zones 8a–8b
Other states to compare
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 96 °F, at or above the 90 °F point where lettuce and spinach bolt and tomato pollen fails.
- Trunk wrapZone 5b is cold enough that winter sun on a young trunk does more damage than the cold does.
- 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
The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates, growing seasons and summer highs are NOAA's 1991–2020 Climate Normals, read from every station in Arizona. Which ZIP codes are in Arizona comes from the Census ZIP-to-county relation, since a county's federal code begins with its state's. Nothing here is estimated.
This page names no single station for Arizona on purpose. Picking one to represent a state sounds reasonable and is not — the same reason the metro pages refuse it, only more so at this size. Instead every range names the station at each end, so you can check both without either one being made to speak for the state.