AMES, Iowa – Strawberry plants can provide a delicious bounty of fruit, year after year. But to keep them coming back, some pre-winter care and preparation is required. What must be done during fall to ready strawberry beds for a cold-weather blast?
ISU Extension and Outreach horticulturists can help answer your questions about strawberry plant beds and how to handle them during the winter.
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.
Allow the strawberry plants to harden or acclimate to cool fall temperatures before mulching the planting. Applying mulch before the strawberry plants have properly hardened may make the plants more susceptible to winter injury. In northern Iowa, strawberries are normally mulched in early November. Gardeners in central and southern Iowa should mulch their strawberry plantings in mid-November and late November, respectively.
Excellent mulching materials include clean, weed-free oat, wheat or soybean straw. Chopped cornstalks 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.
How do I protect strawberry plants growing in a raised bed?
Temperatures in raised beds will likely be several degrees colder than ground level plantings in winter. Because of colder temperatures, strawberry plants growing in raised beds require more protection that ground level sites. Place 6 to 8 inches of straw or chopped cornstalks on raised beds in fall.
How do I protect strawberry plants growing in a container?
Strawberry plants growing in a container will likely be seriously damaged or destroyed if left outdoors on a patio, deck or on the ground surface. One option is to place the container in a cool, protected location (such as an attached, unheated garage) in late November. Periodically check the plants in winter and water the container when the soil becomes dry. Another option is to dig a hole in a protected area and set the container in the ground. Cover the strawberry plants with several inches of straw. The soil and straw mulch will protect the strawberry plants from cold winter temperatures.