Wait for cold before mulching strawberries

Question: I normally cover my strawberries with mulch after the ground starts to freeze. But the weather has been so warm I don’t know what to do this year. Should I still put straw over the plants? Should I wait? P.S.

Answer: The unusually warm weather has many gardeners scratching their heads wondering what to do. So what should you do about your strawberries? Watch the weather forecast and be prepared to take action. Strawberry crowns are damaged by temperatures below 18 degrees so a loose mulch, such as weed-free straw, is needed to protect them in winter. Ideally, you should wait until the top half inch of soil is frozen before laying down the mulch. Most years this occurs in late November to early December. Even during warmer than normal autumns, the soil is usually cold enough to put on the mulch by the middle of December. However, this year the air and soil temperatures aren’t low enough to winter mulch. I suggest holding off on covering your strawberry plants until the weather forecast for nighttime temperatures is below 20 degrees.

If you haven’t done so already, wait to cover perennial flowers and other plants we normally winter mulch. Winter mulch is applied to keep the soil consistently cold to prevent frost heaving that damages plant roots. Covering plant crowns when the soil remains fairly warm and the weather is wet provides a good environment for root and crown rots.

Several people, including my husband, have mentioned their lawns are still green and may need to be mowed. Although it seems bizarre in December, lawns taller than two-and-a-half inches could be mowed to lessen the chance of matting and snow mold diseases.

Question: I have a Japanese maple. Been there 10 years. Never an issue. This fall half of the leaves curled, dried but never fell. The other half of tree was normal. Can’t find any specific problems. The dried leaves have hung on even through the snow. Any ideas? Really think I lost this one! L.W.

Answer: Verticillium wilt immediately came to mind when I read your email. In some cases, wilted leaves on effected stems will hang on instead of dropping. The one-sided pattern is also typical of verticillium wilt in multi-stemmed trees and shrubs.

I’ve seen trees and shrubs survive with verticillium. Prune out infected branches. Fertilize and water to promote active growth.


Kenosha County UW-Extension LogoBarb Larson is horticulture educator for the Kenosha County University of Wisconsin Extension. She holds a master’s of science in horticulture from the University of Wisconsin-Madison. If you have a plant or gardening question, email her at barbara.larson@kenoshacounty.org or call 262-857-1942.