Frost dates for Union, MO
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 11
typical year
Safe to plant
April 28
frost is over in 9 of 10 years
First fall frost
October 23
typical year
Growing season
194 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 14 – 28 | – |
| Spinach | – | Feb 28 – Mar 21 | Aug 28 – Sep 11 |
| Lettuce | – | Mar 14 – Apr 4 | Aug 28 – Sep 11 |
| Radishes | – | Mar 14 – Apr 25 | Sep 11 – 25 |
| Onions | – | Mar 14 – 28 | – |
| Potatoes | – | Mar 21 – Apr 4 | – |
| Carrots | – | Mar 21 – Apr 11 | Jul 31 – Aug 14 |
| Beets | – | Mar 14 – 28 | Aug 14 – 28 |
| Kale | Jan 31 – Feb 14 | Mar 14 – 28 | Aug 14 – 28 |
| Broccoli | Jan 31 – Feb 14 | Mar 28 – Apr 11 | Aug 14 – 28 |
| Cabbage | Jan 17 – 31 | Mar 14 – 28 | Aug 14 – 28 |
| Garlic | – | – | Sep 11 – Oct 2 |
| Warm-season crops | |||
| Tomatoes | Mar 3 – 17 | Apr 28 – May 12 | – |
| Peppers | Feb 24 – Mar 10 | May 5 – 19 | – |
| Cucumbers | – | Apr 28 – May 19 | – |
| Zucchini | – | Apr 28 – May 26 | – |
| Pumpkins | – | Apr 28 – May 19 | – |
| Green beans | – | Apr 28 – Aug 14 | – |
| Sweet corn | – | Apr 28 – May 26 | – |
| Basil | Mar 24 – Apr 7 | May 5 – 12 | – |
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 | April 28 | April 11 | March 26 |
| Fall frost before | October 9 | October 23 | November 5 |
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 March 31 (April 15 in a late year), and the first one in fall around November 3.
Towns that use these dates
This is the nearest NOAA station with frost records for 6 towns.
Union, St. Clair, Parkway, Oak Grove Village, Miramiguoa Park, Charmwood
Where these dates come from
NOAA weather station UNION, MO US (USC00238515), 1991–2020 climate normals. It's the nearest station for 11 zip codes, all within 17 miles:
63013, 63015, 63041, 63060, 63061, 63072, 63077, 63079, 63080, 63084, 63089
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.