Frost dates for South Phoenix, AZ
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
January 21
typical year
Safe to plant
February 20
frost is over in 9 of 10 years
First fall frost
December 16
typical year
Growing season
331 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | Dec 24 – Jan 7 | – |
| Spinach | – | Dec 10 – 31 | Oct 21 – Nov 4 |
| Lettuce | – | Dec 24 – Jan 14 | Oct 21 – Nov 4 |
| Radishes | – | Dec 24 – Feb 4 | Nov 4 – 18 |
| Onions | – | Dec 24 – Jan 7 | – |
| Potatoes | – | Dec 31 – Jan 14 | – |
| Carrots | – | Dec 31 – Jan 21 | Sep 23 – Oct 7 |
| Beets | – | Dec 24 – Jan 7 | Oct 7 – 21 |
| Kale | Nov 12 – 26 | Dec 24 – Jan 7 | Oct 7 – 21 |
| Broccoli | Nov 12 – 26 | Jan 7 – 21 | Oct 7 – 21 |
| Cabbage | Oct 29 – Nov 12 | Dec 24 – Jan 7 | Oct 7 – 21 |
| Garlic | – | – | Nov 4 – 25 |
| Warm-season crops | |||
| Tomatoes | Dec 26 – Jan 9 | Feb 20 – Mar 6 | – |
| Peppers | Dec 19 – Jan 2 | Feb 27 – Mar 13 | – |
| Cucumbers | – | Feb 20 – Mar 13 | – |
| Zucchini | – | Feb 20 – Mar 20 | – |
| Pumpkins | – | Feb 20 – Mar 13 | – |
| Green beans | – | Feb 20 – Oct 7 | – |
| Sweet corn | – | Feb 20 – Mar 20 | – |
| Basil | Jan 16 – 30 | Feb 27 – Mar 6 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | February 20 | January 21 | December 24 |
| Fall frost before | November 29 | December 16 | January 9 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around January 3 (February 8 in a late year), and the first one in fall around December 29.
Where these dates come from
NOAA weather station SOUTH PHOENIX, AZ US (USC00028112), 1991–2020 climate normals. It's the nearest station for 8 zip codes, all within 10 miles:
85007, 85009, 85031, 85035, 85041, 85042, 85044, 85048
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.