The big chill

It's still officially summer. But it will definitely feel like fall tonight, when the temperature is expected to fall to 40 degrees in the metro area.

That's not a freeze, of course, but it's cold enough to make some plants, especially tomatoes, shiver.

"Tomatoes don't like cold weather," said Mary Meyer, University of Minnesota Extension horticulturist and professor.

The plants are unhappy with temps below 50, and the tomatoes themselves are susceptible to injury even in the low 40s.

My tomato plants are still producing, but they've definitely slowed way down these last couple weeks.

Leaves are starting to turn yellow and fall off, and the plants are looking leggy and spindly. There are still green tomatoes on the vines, but they're ripening at a glacial pace now that the days are shorter and cooler.

If you have tomatoes you want to protect, it's a good night to cover the plants with sheeting, according Meyer. "Covering will help somewhat."

If you still have green tomatoes, don't give up on them, Meyer said. "Continue to water. It's still early. I think we'll probably have another two to three weeks of weather for ripening outdoors."