Tempe, Arizona: planting zone & frost dates
Tempe 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 Feb 24 and the first fall frost around Nov 29.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Mar 9 | Nov 18 |
| Typical planning date (30% risk) | Feb 24 | Nov 29 |
| Median (50%) | Feb 13 | Dec 5 |
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 TEMPE ASU, AZ (USC00028499), 2.7 mi (4.3 km) from the city center and 10 ft lower than the city center (-3 m). Record used for the 1991–2020 normals: 24 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Tempe
Tempe spans more than one half-zone. Share of the city's land area by zone (via its 4 ZIP codes): 9b (72%), 10a (28%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Tempe
Dates are counted from the 30%-risk frost dates above (last frost Feb 24, first frost Nov 29). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Dec 30 – Jan 13 | Mar 3 – Mar 17 | — | — |
| Pepper | Dec 16 – Dec 30 | Mar 10 – Mar 24 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Jan 13 – Jan 27 | Feb 10 – Mar 3 | Jan 27 – Mar 10 | Sep 20 – Oct 18 |
| Green Beans | — | — | Mar 3 – Apr 7 | Sep 6 – Sep 20 |
| Sweet Corn | — | — | Mar 3 – Mar 31 | — |
| Zucchini & Summer Squash | Jan 27 – Feb 3 | Mar 3 – Mar 17 | Mar 3 – Mar 24 | Sep 6 – Sep 20 |
| Cucumber | Jan 27 – Feb 3 | Mar 10 – Mar 17 | Mar 3 – Mar 24 | Sep 6 – Sep 20 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Feb 3 – Mar 10 | Sep 6 – Sep 20 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 2 – Dec 16 | Jan 27 – Feb 10 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Jan 27 – Feb 17 | — | — |
| Basil | Jan 13 – Jan 27 | Mar 10 – Mar 24 | Mar 10 – Mar 31 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 13 – Feb 10 | Oct 4 – Nov 1 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 30 – Jan 13 | Jan 27 – Feb 17 | Jan 27 – Feb 17 | Sep 20 – Oct 18 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 30 – Jan 13 | Feb 10 – Mar 3 | — | Sep 6 – Sep 20 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 13 – Feb 3 | Sep 20 – Oct 4 |
| Eggplant | Dec 16 – Dec 30 | Mar 10 – Mar 24 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 30 – Jan 13 | Jan 27 – Feb 10 | — | Sep 6 – Sep 20 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 20 – Mar 10 | Oct 18 – Nov 15 |
| Strawberry | — | Jan 27 – Feb 17 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Feb 3 – Mar 17 | Sep 20 – Oct 4 |
Nearby cities in Arizona
- Chandler — zone 9b, last frost Feb 24, first frost Nov 29
- Gilbert — zone 9b, last frost Feb 12, first frost Dec 3
- Mesa — zone 9b, last frost Feb 12, first frost Dec 2
- Phoenix — zone 9b, last frost Jan 23, first frost Dec 15
- Glendale — zone 9b, last frost Feb 2, first frost Dec 8
- Scottsdale — zone 10a, last frost Feb 13, first frost Dec 11
More: all Arizona cities · other zone 9b cities: Houston, TX, Phoenix, AZ, Jacksonville, FL, San Jose, CA, Fresno, CA, Sacramento, CA, Mesa, AZ, Bakersfield, CA
Tempe gardening questions
When is the last frost in Tempe, AZ?
Plan around Feb 24. At NOAA's Tempe ASU, AZ station, 2.7 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 Feb 13, and after Mar 9 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Jan 16. Springs here are erratic: 56 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 Tempe, AZ?
Start seeds indoors Dec 30 – Jan 13 and set transplants outside Mar 3 – Mar 17, once nights stay above 50°F and the soil is near 60°F. With about 278 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 Tempe?
About 298 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 266 days, and in 1 year in 10 it runs 331 days or more. In fall there is a 10% chance of frost by Nov 18 and a 30% chance by Nov 29. That ranks 14th longest of 16 Arizona cities on this site.
When should I plant a fall garden in Tempe?
Count back from the first fall frost (Nov 29): transplant broccoli Sep 6 – Sep 20; sow kale Sep 20 – Oct 18; sow lettuce Sep 20 – Oct 18; sow radishes Oct 18 – Nov 15. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 19. How the math works: succession and fall planting.
Did Tempe's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Tempe 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 Tempe in zone 9b?
No. Zone 9b covers about 72% of the city's land; the rest is in 10a (28%), measured across the city's 4 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.