Phoenix, Arizona: planting zone & frost dates
Phoenix is in USDA plant hardiness zone 9b, where the average coldest winter night reaches 25 to 30°F (-3.9 to -1.1°C). The typical last spring frost is around Jan 23 and the first fall frost around Dec 15.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 12 | Dec 5 |
| Typical planning date (30% risk) | Jan 23 | Dec 15 |
| Median (50%) | Jan 8 | Dec 25 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station PHOENIX DEER VALLEY MUNI AP, AZ (USW00003184), 8.0 mi (12.9 km) from the city center and 213 ft higher than the city center (+65 m). Record used for the 1991–2020 normals: 21 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Phoenix
Phoenix spans more than one half-zone. Share of the city's land area by zone (via its 49 ZIP codes): 9b (56%), 10a (44%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
ZIP codes in Phoenix and their zones
| ZIP | Zone | Share of city land |
|---|---|---|
| 85085 | 9b | 6.7% |
| 85086 | 9b | 5.7% |
| 85339 | 9b | 4.3% |
| 85042 | 10a | 3.8% |
| 85083 | 9b | 3.8% |
| 85043 | 9b | 3.4% |
| 85087 | 9b | 3.4% |
| 85044 | 10a | 3.2% |
| 85018 | 10a | 2.9% |
| 85050 | 10a | 2.9% |
| 85009 | 10a | 2.8% |
| 85041 | 10a | 2.7% |
| 85331 | 9b | 2.6% |
| 85032 | 9b | 2.4% |
| 85027 | 10a | 2.3% |
| 85254 | 10a | 2.3% |
| 85024 | 10a | 2.2% |
| 85034 | 10a | 2.2% |
| 85008 | 10a | 2.0% |
| 85040 | 10a | 2.0% |
| 85048 | 9b | 1.9% |
| 85022 | 9b | 1.8% |
| 85029 | 9b | 1.8% |
| 85020 | 10a | 1.7% |
| 85054 | 9b | 1.7% |
| 85353 | 9b | 1.7% |
| 85016 | 10a | 1.6% |
| 85037 | 9b | 1.5% |
| 85023 | 9b | 1.4% |
| 85310 | 10a | 1.4% |
| 85021 | 9b | 1.3% |
| 85028 | 10a | 1.3% |
| 85033 | 9b | 1.2% |
| 85051 | 9b | 1.2% |
| 85035 | 9b | 1.1% |
| 85017 | 9b | 1.0% |
| 85053 | 9b | 1.0% |
| 85007 | 10a | 0.9% |
| 85015 | 9b | 0.9% |
| 85006 | 10a | 0.8% |
| 85014 | 10a | 0.8% |
| 85031 | 9b | 0.8% |
| 85045 | 10a | 0.8% |
| 85013 | 9b | 0.7% |
| 85019 | 9b | 0.7% |
| 85003 | 10a | 0.4% |
| 85004 | 10a | 0.4% |
| 85012 | 10a | 0.4% |
| 85026 | 10a | 0.0% |
Vegetable planting calendar for Phoenix
Dates are counted from the 30%-risk frost dates above (last frost Jan 23, first frost Dec 15). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Nov 28 – Dec 12 | Jan 30 – Feb 13 | — | — |
| Pepper | Nov 14 – Nov 28 | Feb 6 – Feb 20 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 12 – Dec 26 | Jan 9 – Jan 30 | Dec 26 – Feb 6 | Oct 6 – Nov 3 |
| Green Beans | — | — | Jan 30 – Mar 6 | Sep 22 – Oct 6 |
| Sweet Corn | — | — | Jan 30 – Feb 27 | — |
| Zucchini & Summer Squash | Dec 26 – Jan 2 | Jan 30 – Feb 13 | Jan 30 – Feb 20 | Sep 22 – Oct 6 |
| Cucumber | Dec 26 – Jan 2 | Feb 6 – Feb 13 | Jan 30 – Feb 20 | Sep 22 – Oct 6 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 2 – Feb 6 | Sep 22 – Oct 6 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Oct 31 – Nov 14 | Dec 26 – Jan 9 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Dec 26 – Jan 16 | — | — |
| Basil | Dec 12 – Dec 26 | Feb 6 – Feb 20 | Feb 6 – Feb 27 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 12 – Jan 9 | Oct 20 – Nov 17 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 28 – Dec 12 | Dec 26 – Jan 16 | Dec 26 – Jan 16 | Oct 6 – Nov 3 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 28 – Dec 12 | Jan 9 – Jan 30 | — | Sep 22 – Oct 6 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 12 – Jan 2 | Oct 6 – Oct 20 |
| Eggplant | Nov 14 – Nov 28 | Feb 6 – Feb 20 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 28 – Dec 12 | Dec 26 – Jan 9 | — | Sep 22 – Oct 6 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 19 – Feb 6 | Nov 3 – Dec 1 |
| Strawberry | — | Dec 26 – Jan 16 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 2 – Feb 13 | Oct 6 – Oct 20 |
Nearby cities in Arizona
- Glendale — zone 9b, last frost Feb 2, first frost Dec 8
- Tempe — zone 9b, last frost Feb 24, first frost Nov 29
- Scottsdale — zone 10a, last frost Feb 13, first frost Dec 11
- Avondale — zone 9b, last frost Jan 18, first frost Dec 16
- Peoria — zone 9b, last frost Feb 16, first frost Dec 2
- Chandler — zone 9b, last frost Feb 24, first frost Nov 29
More: all Arizona cities · other zone 9b cities: Houston, TX, Jacksonville, FL, San Jose, CA, Fresno, CA, Sacramento, CA, Mesa, AZ, Bakersfield, CA, New Orleans, LA
Phoenix gardening questions
When is the last frost in Phoenix, AZ?
Plan around Jan 23. At NOAA's Phoenix Deer Valley Municipal Airport, AZ station, 8.0 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Jan 8, and after Feb 12 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Jan 8. Springs here are erratic: 58 days separate the 90% and 10% dates, versus a median of 36 days for cities on this site, so watch the forecast rather than the calendar.
When should I plant tomatoes in Phoenix, AZ?
Start seeds indoors Nov 28 – Dec 12 and set transplants outside Jan 30 – Feb 13, once nights stay above 50°F and the soil is near 60°F. With about 326 frost-free days, frost is not the main limit — fruit set drops when nights stay above about 75°F, so early plantings tend to do best. More: tomato planting dates by zone.
How long is the growing season in Phoenix?
About 354 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 320 days, and in 1 year in 10 it runs 365 days or more. In fall there is a 10% chance of frost by Dec 5 and a 30% chance by Dec 15. That is the longest of the 16 Arizona cities on this site.
When should I plant a fall garden in Phoenix?
Count back from the first fall frost (Dec 15): transplant broccoli Sep 22 – Oct 6; sow kale Oct 6 – Nov 3; sow lettuce Oct 6 – Nov 3; sow radishes Nov 3 – Dec 1. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Jan 7. How the math works: succession and fall planting.
Did Phoenix's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Phoenix is zone 9b on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
Is all of Phoenix in zone 9b?
No. Zone 9b covers about 56% of the city's land; the rest is in 10a (44%), measured across the city's 49 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.