Frost dates for Ajo, 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 10
typical year
Safe to plant
February 15
frost is over in 9 of 10 years
First fall frost
December 21
typical year
Growing season
347 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 13 – 27 | – |
| Spinach | – | Nov 29 – Dec 20 | Oct 26 – Nov 9 |
| Lettuce | – | Dec 13 – Jan 3 | Oct 26 – Nov 9 |
| Radishes | – | Dec 13 – Jan 24 | Nov 9 – 23 |
| Onions | – | Dec 13 – 27 | – |
| Potatoes | – | Dec 20 – Jan 3 | – |
| Carrots | – | Dec 20 – Jan 10 | Sep 28 – Oct 12 |
| Beets | – | Dec 13 – 27 | Oct 12 – 26 |
| Kale | Nov 1 – 15 | Dec 13 – 27 | Oct 12 – 26 |
| Broccoli | Nov 1 – 15 | Dec 27 – Jan 10 | Oct 12 – 26 |
| Cabbage | Oct 18 – Nov 1 | Dec 13 – 27 | Oct 12 – 26 |
| Garlic | – | – | Nov 9 – 30 |
| Warm-season crops | |||
| Tomatoes | Dec 21 – Jan 4 | Feb 15 – Mar 1 | – |
| Peppers | Dec 14 – 28 | Feb 22 – Mar 8 | – |
| Cucumbers | – | Feb 15 – Mar 8 | – |
| Zucchini | – | Feb 15 – Mar 15 | – |
| Pumpkins | – | Feb 15 – Mar 8 | – |
| Green beans | – | Feb 15 – Oct 12 | – |
| Sweet corn | – | Feb 15 – Mar 15 | – |
| Basil | Jan 11 – 25 | Feb 22 – Mar 1 | – |
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 15 | January 10 | December 11 |
| Fall frost before | November 25 | December 21 | January 24 |
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 8 (February 10 in a late year), and the first one in fall around January 3.
Where these dates come from
NOAA weather station AJO, AZ US (USC00020080), 1991–2020 climate normals. It's the nearest station for 1 zip code, all within 16 miles:
85321
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.