Frost dates for Monmouth, IL
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
April 22
typical year
Safe to plant
May 10
frost is over in 9 of 10 years
First fall frost
October 15
typical year
Growing season
174 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 | – | Mar 25 – Apr 8 | – |
| Spinach | – | Mar 11 – Apr 1 | Aug 20 – Sep 3 |
| Lettuce | – | Mar 25 – Apr 15 | Aug 20 – Sep 3 |
| Radishes | – | Mar 25 – May 6 | Sep 3 – 17 |
| Onions | – | Mar 25 – Apr 8 | – |
| Potatoes | – | Apr 1 – 15 | – |
| Carrots | – | Apr 1 – 22 | Jul 23 – Aug 6 |
| Beets | – | Mar 25 – Apr 8 | Aug 6 – 20 |
| Kale | Feb 11 – 25 | Mar 25 – Apr 8 | Aug 6 – 20 |
| Broccoli | Feb 11 – 25 | Apr 8 – 22 | Aug 6 – 20 |
| Cabbage | Jan 28 – Feb 11 | Mar 25 – Apr 8 | Aug 6 – 20 |
| Garlic | – | – | Sep 3 – 24 |
| Warm-season crops | |||
| Tomatoes | Mar 15 – 29 | May 10 – 24 | – |
| Peppers | Mar 8 – 22 | May 17 – 31 | – |
| Cucumbers | – | May 10 – 31 | – |
| Zucchini | – | May 10 – Jun 7 | – |
| Pumpkins | – | May 10 – 31 | – |
| Green beans | – | May 10 – Aug 6 | – |
| Sweet corn | – | May 10 – Jun 7 | – |
| Basil | Apr 5 – 19 | May 17 – 24 | – |
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 10 | April 22 | April 9 |
| Fall frost before | September 29 | October 15 | October 27 |
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 April 11 (April 28 in a late year), and the first one in fall around October 25.
Towns that use these dates
This is the nearest NOAA station with frost records for 2 towns.
Monmouth, Alexis
Where these dates come from
NOAA weather station MONMOUTH, IL US (USC00115768), 1991–2020 climate normals. It's the nearest station for 3 zip codes, all within 9 miles:
61412, 61435, 61462
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.