Frost dates for Simla, CO
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
May 12
typical year
Safe to plant
May 26
frost is over in 9 of 10 years
First fall frost
October 2
typical year
Growing season
141 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 | – | Apr 14 – 28 | – |
| Spinach | – | Mar 31 – Apr 21 | Aug 7 – 21 |
| Lettuce | – | Apr 14 – May 5 | Aug 7 – 21 |
| Radishes | – | Apr 14 – May 26 | Aug 21 – Sep 4 |
| Onions | – | Apr 14 – 28 | – |
| Potatoes | – | Apr 21 – May 5 | – |
| Carrots | – | Apr 21 – May 12 | Jul 10 – 24 |
| Beets | – | Apr 14 – 28 | Jul 24 – Aug 7 |
| Kale | Mar 3 – 17 | Apr 14 – 28 | Jul 24 – Aug 7 |
| Broccoli | Mar 3 – 17 | Apr 28 – May 12 | Jul 24 – Aug 7 |
| Cabbage | Feb 17 – Mar 3 | Apr 14 – 28 | Jul 24 – Aug 7 |
| Garlic | – | – | Aug 21 – Sep 11 |
| Warm-season crops | |||
| Tomatoes | Mar 31 – Apr 14 | May 26 – Jun 9 | – |
| Peppers | Mar 24 – Apr 7 | Jun 2 – 16 | – |
| Cucumbers | – | May 26 – Jun 16 | – |
| Zucchini | – | May 26 – Jun 23 | – |
| Pumpkins | – | May 26 – Jun 16 | – |
| Green beans | – | May 26 – Jul 24 | – |
| Sweet corn | – | May 26 – Jun 23 | – |
| Basil | Apr 21 – May 5 | Jun 2 – 9 | – |
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 | May 26 | May 12 | May 1 |
| Fall frost before | September 19 | October 2 | October 14 |
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 May 2 (May 15 in a late year), and the first one in fall around October 11.
Towns that use these dates
This is the nearest NOAA station with frost records for 2 towns.
Simla, Ramah
Where these dates come from
NOAA weather station MATHESON 8 SE, CO US (USC00055427), 1991–2020 climate normals. It's the nearest station for 2 zip codes, all within 11 miles:
80830, 80835
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.