Strawberries should be mulched in the fall to prevent winter injury. Temperatures below +20 F may kill flower buds and damage the roots and crowns of unmulched plants. Repeated freezing and thawing of the soil through the winter months can heave unmulched plants out of the soil and also damage plants. Excellent mulching materials include clean, weed-free straw and chopped cornstalks. (Leaves are not a good mulch for strawberries. Leaves tend to mat together and do not provide adequate protection.) Apply 3 to 5 inches of the material. After settling, the depth of the mulch should be approximately 2 to 4 inches.
Allow the strawberry plants to harden or acclimate to the cool fall temperatures before mulching the bed. In northern Iowa, strawberries are normally mulched in late October to early November. Gardeners in central and southern Iowa should mulch their strawberries in early to mid-November and mid- to late November, respectively. The mulch should remain on the strawberry plants until about mid-April.
This article originally appeared in the October 11, 1996 issue, p. 165.