As they do with quite a few other fruits and veggies, gardeners must prepare strawberry plants for winter to enable a successful harvest next spring. In this installment of Yard and Garden, Cynthia Haynes, associate professor and extension specialist in horticulture at Iowa State University, answers questions about that topic.
My strawberry plants are growing in a strawberry pyramid. How do I protect the plants over winter?
A strawberry pyramid is a type of raised bed. In winter, temperatures in raised beds may be several degrees colder than ground-level plantings. Because of colder temperatures, strawberry plants growing in raised beds require more protection than ground level sites. Place 6-8 inches of straw or chopped cornstalks on strawberry pyramids or other raised beds in fall.
How should I prepare my strawberry bed for winter?
Strawberries should be mulched in fall to prevent winter injury. Low 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. Repeated freezing and thawing of the soil can heave plants out of the ground, severely damaging or destroying the plants.
Excellent mulching materials include clean, weed-free oat, wheat or soybean straw. Chopped corn stalks are another possibility. Apply approximately 3 to 5 inches of material. After settling, the mulch layer should be 2 to 4 inches thick.
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.
When should I mulch my strawberries?
Allow the strawberry plants to harden or acclimate to cool fall temperatures before mulching the bed. In northern Iowa, strawberry plantings are normally mulched in early November. Gardeners in central and southern Iowa should mulch their strawberries in mid-November and late November, respectively.