UPDATE, Oct. 7, 2022: If you’ve escaped the frost so far, take heed tonight, as a freeze warning has been issued in Iowa, with temperatures predicted to dip into the 20s from Friday into Saturday.
One week ago, parts of Iowa sustained record heat on Sept. 20, 2022, with temperatures in the upper 90s. Tonight, the state could experience the first frost of fall.
This is Iowa.
Forecasts call for lows overnight (Sept. 27-28) in the 30s and with calm conditions, the potential for the state’s first frost of the season.
According to Iowa State University Extension & Outreach, the average date of the first 32 degree temperature in Iowa ranges from Sept. 30 in far northwest Iowa to Oct. 15 in the southeast.
By some definitions, a hard, or killing freeze, happens when temperatures remain at a sustained 28 degrees. Given that forecasts predict temperatures in the 30s overnight this week, some plants should be safe.
As a precaution for tender vegetation, such as some flowers, tomatoes and peppers, a bedsheet or light blanket can be used to cover the plants overnight and removed in the morning, once temperatures have rebounded. Plastic usually isn’t as effective.
If you want to be on the safe side, tomatoes, peppers, cucumbers and other vegetables can be harvested before the predicted frost. Green tomatoes will ripen indoors if kept unrefrigerated.
Plants in containers can be moved into a garage or porch where they will be protected, and returned outdoors once the chance for frost has passed.
Hardier vegetables, such as carrots and kale, can survive a frost and even a freeze.