Frost dates for Tohono Chul, 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
February 26
typical year
Safe to plant
March 18
frost is over in 9 of 10 years
First fall frost
December 4
typical year
Growing season
279 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 | – | Jan 29 – Feb 12 | – |
| Spinach | – | Jan 15 – Feb 5 | Oct 9 – 23 |
| Lettuce | – | Jan 29 – Feb 19 | Oct 9 – 23 |
| Radishes | – | Jan 29 – Mar 12 | Oct 23 – Nov 6 |
| Onions | – | Jan 29 – Feb 12 | – |
| Potatoes | – | Feb 5 – 19 | – |
| Carrots | – | Feb 5 – 26 | Sep 11 – 25 |
| Beets | – | Jan 29 – Feb 12 | Sep 25 – Oct 9 |
| Kale | Dec 18 – Jan 1 | Jan 29 – Feb 12 | Sep 25 – Oct 9 |
| Broccoli | Dec 18 – Jan 1 | Feb 12 – 26 | Sep 25 – Oct 9 |
| Cabbage | Dec 4 – 18 | Jan 29 – Feb 12 | Sep 25 – Oct 9 |
| Garlic | – | – | Oct 23 – Nov 13 |
| Warm-season crops | |||
| Tomatoes | Jan 21 – Feb 4 | Mar 18 – Apr 1 | – |
| Peppers | Jan 14 – 28 | Mar 25 – Apr 8 | – |
| Cucumbers | – | Mar 18 – Apr 8 | – |
| Zucchini | – | Mar 18 – Apr 15 | – |
| Pumpkins | – | Mar 18 – Apr 8 | – |
| Green beans | – | Mar 18 – Sep 25 | – |
| Sweet corn | – | Mar 18 – Apr 15 | – |
| Basil | Feb 11 – 25 | Mar 25 – Apr 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 | March 18 | February 26 | January 29 |
| Fall frost before | November 17 | December 4 | December 19 |
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 February 1 (February 27 in a late year), and the first one in fall around December 17.
Where these dates come from
NOAA weather station TOHONO CHUL, AZ US (USC00028590), 1991–2020 climate normals. It's the nearest station for 3 zip codes, all within 5 miles:
85704, 85741, 85742
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.