To insure a bountiful strawberry crop next year, home gardeners should mulch their strawberry plantings this fall.

Cold winter temperatures and repeated freezing and thawing of the soil through the winter months are the main threats to strawberry plants. Temperatures below +20 degrees Fahrenheit may kill flower buds and damage the roots and crowns of unmulched plants. Plants can also be destroyed by repeated freezing and thawing of the soil, which can heave unmulched plants out of the ground.

Strawberries should be mulched in fall before temperatures drop below +20 degrees Fahrenheit. However, allow the strawberry plants to harden or acclimate to cool fall temperatures before mulching the planting. Plants that are mulched prematurely are more susceptible to winter injury than those that are mulched after they have been properly hardened. In northern Iowa, strawberries are normally mulched in late October to early November. Gardeners in central and southern Iowa should mulch their strawberry plantings in mid-November and mid- to late November, respectively.

Excellent mulching materials include clean, weed-free oat, wheat, or soybean straw. Chopped cornstalks are another possibility. The depth of the mulch should be 3 to 5 inches at application. The material should eventually settle to 2 to 4 inches.

In windy, exposed areas, straw mulches can be kept in place by placing wire or plastic fencing over the area. The fencing can be held in place with bricks or other heavy objects.

Leaves are not a good winter mulch for strawberries. Leaves can mat together in layers, trapping air and creating space for ice to form. The leaf, air, and ice layers do not provide adequate protection. Leaf mulch may actually damage plants due to excess moisture trapped under the material.