Frost dates for Castle Hot Springs, 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 15
typical year
Safe to plant
February 21
frost is over in 9 of 10 years
First fall frost
December 22
typical year
Growing season
341 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 18 – Jan 1 | – |
| Spinach | – | Dec 4 – 25 | Oct 27 – Nov 10 |
| Lettuce | – | Dec 18 – Jan 8 | Oct 27 – Nov 10 |
| Radishes | – | Dec 18 – Jan 29 | Nov 10 – 24 |
| Onions | – | Dec 18 – Jan 1 | – |
| Potatoes | – | Dec 25 – Jan 8 | – |
| Carrots | – | Dec 25 – Jan 15 | Sep 29 – Oct 13 |
| Beets | – | Dec 18 – Jan 1 | Oct 13 – 27 |
| Kale | Nov 6 – 20 | Dec 18 – Jan 1 | Oct 13 – 27 |
| Broccoli | Nov 6 – 20 | Jan 1 – 15 | Oct 13 – 27 |
| Cabbage | Oct 23 – Nov 6 | Dec 18 – Jan 1 | Oct 13 – 27 |
| Garlic | – | – | Nov 10 – Dec 1 |
| Warm-season crops | |||
| Tomatoes | Dec 27 – Jan 10 | Feb 21 – Mar 7 | – |
| Peppers | Dec 20 – Jan 3 | Feb 28 – Mar 14 | – |
| Cucumbers | – | Feb 21 – Mar 14 | – |
| Zucchini | – | Feb 21 – Mar 21 | – |
| Pumpkins | – | Feb 21 – Mar 14 | – |
| Green beans | – | Feb 21 – Oct 13 | – |
| Sweet corn | – | Feb 21 – Mar 21 | – |
| Basil | Jan 17 – 31 | Feb 28 – Mar 7 | – |
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 21 | January 15 | December 19 |
| Fall frost before | November 29 | December 22 | January 26 |
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 9 (February 15 in a late year), and the first one in fall around January 6.
Where these dates come from
NOAA weather station CASTLE HOT SPRINGS, AZ US (USC00021353), 1991–2020 climate normals. It's the nearest station for 2 zip codes, all within 13 miles:
85087, 85342
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.