Remember all those posts we’ve had in the past about last frost date. You know, this one, this one and this one.

Here’s the thing to remember. Mother Nature doesn’t read this blog. Sometimes, she throws a bit of a curve.

frost on artemisia

Most perennials, such as this Silver Mound artemisia, will have no problem with the cool nights we have ahead.

Over the next five nights, we will be getting temperatures very close to freezing. Friday and Saturday nights look like the worst of it in Minnesota, when a freeze is possible in many parts of the state. Gardeners should get outside and cover up or if possible, bring into the house, any tender annuals that have already been planted—things like petunias, geraniums, basil or other summer flowers and herbs. (Don’t worry about pansies and other cool-season annuals — they can take the cold.) You can remove the covers during the day as the temperatures will rise into the 50s or 60s.

While most perennials that are up can take the cold, you may want to cover any peonies that have buds on them (as mine do) to preserve flowers for this year.

Lettuce and other cold-season crops can generally handle a light frost pretty well, but if you are concerned that your vegetables are in a low or particularly cold spot, it won’t hurt to throw a sheet over them at night. Be sure to remove it during the day.

Fruit trees should be OK, too. Many are in bloom now and sustained temperatures below 32 degrees can harm blossoms and reduce (or eliminate) fruit set. The current forecast doesn’t call for temperatures below 32, but you should keep an eye on it.

Hang in there! The long-range forecast looks much better. It won’t be long before we will be complaining about the heat.

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