Maricopa, Arizona: planting zone & frost dates
Maricopa is in USDA plant hardiness zone 9a, where the average coldest winter night reaches 20 to 25°F (-6.7 to -3.9°C). The typical last spring frost is around Mar 3 and the first fall frost around Nov 18.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Mar 15 | Nov 10 |
| Typical planning date (30% risk) | Mar 3 | Nov 18 |
| Median (50%) | Feb 23 | Nov 24 |
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 MARICOPA 4 N, AZ (USC00025270), 5.3 mi (8.5 km) from the city center and 36 ft lower than the city center (-11 m). Record used for the 1991–2020 normals: 22 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Maricopa
All 3 ZIP codes covering Maricopa are in zone 9a.
Vegetable planting calendar for Maricopa
Dates are counted from the 30%-risk frost dates above (last frost Mar 3, first frost Nov 18). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Jan 6 – Jan 20 | Mar 10 – Mar 24 | — | — |
| Pepper | Dec 23 – Jan 6 | Mar 17 – Mar 31 | — | — |
| Lettuce | Jan 20 – Feb 3 | Feb 17 – Mar 10 | Feb 3 – Mar 17 | Sep 9 – Oct 7 |
| Green Beans | — | — | Mar 10 – Apr 14 | Aug 26 – Sep 9 |
| Sweet Corn | — | — | Mar 10 – Apr 7 | — |
| Zucchini & Summer Squash | Feb 3 – Feb 10 | Mar 10 – Mar 24 | Mar 10 – Mar 31 | Aug 26 – Sep 9 |
| Cucumber | Feb 3 – Feb 10 | Mar 17 – Mar 24 | Mar 10 – Mar 31 | Aug 26 – Sep 9 |
| Carrot | — | — | Feb 10 – Mar 17 | Aug 26 – Sep 9 |
| Onion | Dec 9 – Dec 23 | Feb 3 – Feb 17 | — | — |
| Potato | — | Feb 3 – Feb 24 | — | — |
| Basil | Jan 20 – Feb 3 | Mar 17 – Mar 31 | Mar 17 – Apr 7 | — |
| Spinach | — | — | Jan 20 – Feb 17 | Sep 23 – Oct 21 |
| Kale | Jan 6 – Jan 20 | Feb 3 – Feb 24 | Feb 3 – Feb 24 | Sep 9 – Oct 7 |
| Broccoli | Jan 6 – Jan 20 | Feb 17 – Mar 10 | — | Aug 26 – Sep 9 |
| Peas | — | — | Jan 20 – Feb 10 | Sep 9 – Sep 23 |
| Eggplant | Dec 23 – Jan 6 | Mar 17 – Mar 31 | — | — |
| Cabbage | Jan 6 – Jan 20 | Feb 3 – Feb 17 | — | Aug 26 – Sep 9 |
| Radish | — | — | Jan 27 – Mar 17 | Oct 7 – Nov 4 |
| Strawberry | — | Feb 3 – Feb 24 | — | — |
| Beets | — | — | Feb 10 – Mar 24 | Sep 9 – Sep 23 |
Nearby cities in Arizona
- Chandler — zone 9b, last frost Feb 24, first frost Nov 29
- Tempe — zone 9b, last frost Feb 24, first frost Nov 29
- Gilbert — zone 9b, last frost Feb 12, first frost Dec 3
- Goodyear — zone 9b, last frost Jan 29, first frost Dec 12
- Queen Creek — zone 9b, last frost Feb 12, first frost Dec 3
- Mesa — zone 9b, last frost Feb 12, first frost Dec 2
More: all Arizona cities · other zone 9a cities: San Antonio, TX, Austin, TX, Seattle, WA, Las Vegas, NV, Portland, OR, Tucson, AZ, Baton Rouge, LA, Tallahassee, FL
Maricopa gardening questions
When is the last frost in Maricopa, AZ?
Plan around Mar 3. At NOAA's Maricopa 4 N, AZ station, 5.3 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 23, and after Mar 15 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Feb 2. The 90% and 10% dates are 45 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in Maricopa, AZ?
Start seeds indoors Jan 6 – Jan 20 and set transplants outside Mar 10 – Mar 24, once nights stay above 50°F and the soil is near 60°F. With about 260 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 Maricopa?
About 274 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 245 days, and in 1 year in 10 it runs 304 days or more. In fall there is a 10% chance of frost by Nov 10 and a 30% chance by Nov 18. That ranks 15th longest of 16 Arizona cities on this site.
When should I plant a fall garden in Maricopa?
Count back from the first fall frost (Nov 18): transplant broccoli Aug 26 – Sep 9; sow kale Sep 9 – Oct 7; sow lettuce Sep 9 – Oct 7; sow radishes Oct 7 – Nov 4. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 6. How the math works: succession and fall planting.
Did Maricopa's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Maricopa is zone 9a 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.
How does Maricopa compare with Chandler, AZ?
Maricopa is zone 9a and Chandler is zone 9b. The typical last spring frost in Maricopa (Mar 3) comes about 7 days later than in Chandler, AZ (Feb 24), 19 miles away, and the first fall frost is Nov 18 versus Nov 29. The two cities use different NOAA stations.