Mount Morris, IL frost dates
Last spring frostApr 29median date
First fall frostOct 7median date
Growing season161 daysfrost-free
Hardiness zone5bZone 5b
How Mount Morris compares
- In 8 years out of 10, the last spring frost in Mount Morris falls between April 15 and May 14, a 29-day window. The first fall frost falls between September 23 and October 22.
- The median last frost is 12 days later than the Illinois median of Apr 17.
- Its 161-day growing season is among the shortest of the 1,287 Illinois places with a regular frost season.
- The last frost is typical for zone 5b, where the median is May 1.
- The weather station records an average of 138 nights a year at or below 32°F.
- Compared with Rockford, IL, 39 km away, the last frost here is 5 days later than there and the growing season is 15 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 15 |
| 50% (median) | April 29 |
| 10% (safe for tender plants) | May 14 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 23 |
| 50% (median) | October 7 |
| 90% (late) | October 22 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Mount Morris, IL
Mount Morris, IL frost dates — last frost Apr 29, first frost Oct 7, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Feb 4 to Feb 18Transplant outside: Apr 1 to Apr 15
Start indoors: Feb 18 to Mar 4Transplant outside: May 13 to May 27
Start indoors: Feb 18 to Mar 4Transplant outside: May 13 to May 27
Start indoors: Mar 4 to Mar 18Transplant outside: May 6 to May 20
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 8 to Apr 22Sow outdoors: Apr 1 to May 6Plant for fall: Aug 12 to Sep 9
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 1 to Apr 15Sow outdoors: Apr 1 to Apr 15Plant for fall: Jul 29 to Aug 19
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 15 to Apr 29Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 8 to Apr 22Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 15 to Apr 29Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 18 to Apr 1Transplant outside: May 20 to Jun 3Sow outdoors: May 20 to Jun 3
Start indoors: Mar 18 to Apr 1Transplant outside: May 6 to May 20
Sow outdoors: Mar 18 to Apr 8Plant for fall: Jul 15 to Aug 5
Sow outdoors: Mar 18 to Apr 8Plant for fall: Aug 12 to Sep 2
Sow outdoors: Mar 25 to May 6Plant for fall: Aug 26 to Sep 16
Start indoors: Apr 1 to Apr 8Transplant outside: May 13 to May 20Sow outdoors: May 6 to May 20Plant for fall: Jul 22 to Aug 5
Start indoors: Apr 1 to Apr 8Sow outdoors: May 6 to May 20Plant for fall: Jul 29 to Aug 12
Start indoors: Apr 1 to Apr 8Sow outdoors: May 6 to May 20
Start indoors: Apr 1 to Apr 8Transplant outside: May 13 to May 27
Sow outdoors: Apr 8 to May 6Plant for fall: Jul 15 to Jul 29
Sow outdoors: Apr 8 to May 6Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 8 to Apr 29
Sow outdoors: Apr 15 to May 13Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 15 to May 6Plant for fall: Aug 12 to Sep 2
Sow outdoors: May 6 to May 27Plant for fall: Jul 22 to Aug 5
Sow outdoors: May 6 to May 20
Transplant outside: May 13 to Jun 3
Plant for fall: Sep 23 to Oct 28
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Mount Morris, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 4 – Feb 18 | Apr 1 – Apr 15 | — | — |
| Peppers | Feb 18 – Mar 4 | May 13 – May 27 | — | — |
| Eggplant | Feb 18 – Mar 4 | May 13 – May 27 | — | — |
| Tomatoes | Mar 4 – Mar 18 | May 6 – May 20 | — | — |
| Lettuce | Mar 4 – Mar 18 | Apr 8 – Apr 22 | Apr 1 – May 6 | Aug 12 – Sep 9 |
| Kale | Mar 4 – Mar 18 | Apr 1 – Apr 15 | Apr 1 – Apr 15 | Jul 29 – Aug 19 |
| Broccoli | Mar 4 – Mar 18 | Apr 15 – Apr 29 | — | Jul 1 – Jul 22 |
| Cabbage | Mar 4 – Mar 18 | Apr 8 – Apr 22 | — | Jul 1 – Jul 22 |
| Cauliflower | Mar 4 – Mar 18 | Apr 15 – Apr 29 | — | Jul 1 – Jul 22 |
| Okra | Mar 18 – Apr 1 | May 20 – Jun 3 | May 20 – Jun 3 | — |
| Basil | Mar 18 – Apr 1 | May 6 – May 20 | — | — |
| Peas | — | — | Mar 18 – Apr 8 | Jul 15 – Aug 5 |
| Spinach | — | — | Mar 18 – Apr 8 | Aug 12 – Sep 2 |
| Radishes | — | — | Mar 25 – May 6 | Aug 26 – Sep 16 |
| Cucumbers | Apr 1 – Apr 8 | May 13 – May 20 | May 6 – May 20 | Jul 22 – Aug 5 |
| Zucchini & Summer Squash | Apr 1 – Apr 8 | — | May 6 – May 20 | Jul 29 – Aug 12 |
| Winter Squash & Pumpkins | Apr 1 – Apr 8 | — | May 6 – May 20 | — |
| Melons & Watermelon | Apr 1 – Apr 8 | May 13 – May 27 | — | — |
| Carrots | — | — | Apr 8 – May 6 | Jul 15 – Jul 29 |
| Beets | — | — | Apr 8 – May 6 | Jul 29 – Aug 12 |
| Potatoes | — | — | Apr 8 – Apr 29 | — |
| Swiss Chard | — | — | Apr 15 – May 13 | Jul 29 – Aug 12 |
| Cilantro | — | — | Apr 15 – May 6 | Aug 12 – Sep 2 |
| Green Beans | — | — | May 6 – May 27 | Jul 22 – Aug 5 |
| Sweet Corn | — | — | May 6 – May 20 | — |
| Sweet Potatoes | — | May 13 – Jun 3 | — | — |
| Garlic | — | — | — | Sep 23 – Oct 28 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Polo 5nw, IL weather station, 14 km away (elevation 856 ft (261 m)).
Frost dates near Mount Morris
- Oregon Apr 29 · Oct 7
- Leaf River Apr 29 · Oct 7
- Forreston Apr 29 · Oct 7
- Polo Apr 29 · Oct 7
- Byron Apr 24 · Oct 17
- Woosung Apr 21 · Oct 19
- German Valley Apr 26 · Oct 13
- Chana Apr 26 · Oct 13
- Baileyville Apr 26 · Oct 13
- Stillman Valley Apr 24 · Oct 17
Frequently asked questions
When is the last frost in Mount Morris, IL?
The median last spring frost in Mount Morris, IL is April 29. There is still about a 10% chance of frost after May 14, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Mount Morris, IL?
The median first fall frost is October 7, with about a 10% chance of frost before September 23.
How long is the growing season in Mount Morris, IL?
About 161 days between the median last spring frost and first fall frost.
What planting zone is Mount Morris, IL?
Mount Morris, IL is in USDA hardiness zone 5b.