Glendale, Arizona: planting zone & frost dates
Glendale 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 2 and the first fall frost around Dec 8.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 18 | Nov 28 |
| Typical planning date (30% risk) | Feb 2 | Dec 8 |
| Median (50%) | Jan 20 | Dec 15 |
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 YOUNGTOWN, AZ (USC00029634), 7.7 mi (12.4 km) from the city center and 7 ft lower than the city center (-2 m). Record used for the 1991–2020 normals: 29 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Glendale
Glendale spans more than one half-zone. Share of the city's land area by zone (via its 13 ZIP codes): 9b (97%), 10a (3%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Glendale
Dates are counted from the 30%-risk frost dates above (last frost Feb 2, first frost Dec 8). 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 8 – Dec 22 | Feb 9 – Feb 23 | — | — |
| Pepper | Nov 24 – Dec 8 | Feb 16 – Mar 2 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 22 – Jan 5 | Jan 19 – Feb 9 | Jan 5 – Feb 16 | Sep 29 – Oct 27 |
| Green Beans | — | — | Feb 9 – Mar 16 | Sep 15 – Sep 29 |
| Sweet Corn | — | — | Feb 9 – Mar 9 | — |
| Zucchini & Summer Squash | Jan 5 – Jan 12 | Feb 9 – Feb 23 | Feb 9 – Mar 2 | Sep 15 – Sep 29 |
| Cucumber | Jan 5 – Jan 12 | Feb 16 – Feb 23 | Feb 9 – Mar 2 | Sep 15 – Sep 29 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 12 – Feb 16 | Sep 15 – Sep 29 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 10 – Nov 24 | Jan 5 – Jan 19 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Jan 5 – Jan 26 | — | — |
| Basil | Dec 22 – Jan 5 | Feb 16 – Mar 2 | Feb 16 – Mar 9 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 22 – Jan 19 | Oct 13 – Nov 10 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 8 – Dec 22 | Jan 5 – Jan 26 | Jan 5 – Jan 26 | Sep 29 – Oct 27 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 8 – Dec 22 | Jan 19 – Feb 9 | — | Sep 15 – Sep 29 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 22 – Jan 12 | Sep 29 – Oct 13 |
| Eggplant | Nov 24 – Dec 8 | Feb 16 – Mar 2 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 8 – Dec 22 | Jan 5 – Jan 19 | — | Sep 15 – Sep 29 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 29 – Feb 16 | Oct 27 – Nov 24 |
| Strawberry | — | Jan 5 – Jan 26 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 12 – Feb 23 | Sep 29 – Oct 13 |
Nearby cities in Arizona
- Phoenix — zone 9b, last frost Jan 23, first frost Dec 15
- Avondale — zone 9b, last frost Jan 18, first frost Dec 16
- Peoria — zone 9b, last frost Feb 16, first frost Dec 2
- Tempe — zone 9b, last frost Feb 24, first frost Nov 29
- Surprise — zone 9b, last frost Feb 16, first frost Dec 2
- Goodyear — zone 9b, last frost Jan 29, first frost Dec 12
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
Glendale gardening questions
When is the last frost in Glendale, AZ?
Plan around Feb 2. At NOAA's Youngtown, AZ station, 7.7 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 Jan 20, and after Feb 18 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Jan 3. Springs here are erratic: 57 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 Glendale, AZ?
Start seeds indoors Dec 8 – Dec 22 and set transplants outside Feb 9 – Feb 23, once nights stay above 50°F and the soil is near 60°F. With about 309 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 Glendale?
About 331 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 297 days, and in 1 year in 10 it runs 358 days or more. In fall there is a 10% chance of frost by Nov 28 and a 30% chance by Dec 8. That ranks 5th longest of 16 Arizona cities on this site.
When should I plant a fall garden in Glendale?
Count back from the first fall frost (Dec 8): transplant broccoli Sep 15 – Sep 29; sow kale Sep 29 – Oct 27; sow lettuce Sep 29 – Oct 27; sow radishes Oct 27 – Nov 24. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 29. How the math works: succession and fall planting.
Did Glendale's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Glendale 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 Glendale in zone 9b?
No. Zone 9b covers about 97% of the city's land; the rest is in 10a (3%), measured across the city's 13 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.