Ask a gardener or farmer when to mulch strawberries and you will get answers like: “when the leaves turn red,” “after several hard freezes,” “after Thanksgiving,” or “when the leaves flatten.” These may seem like frustrating, vague answers to those who are new to gardening. However, when to mulch strawberry plants for winter protection depends on a variety of factors, such as your climate zone and the weather each particular year. Read on for some strawberry mulch info.
About Mulch for Strawberries
Strawberry plants are mulched once or twice a year for two very important reasons. In climates with cold winters, mulch is heaped over strawberry plants in late fall or early winter to protect the plant’s root and crown from the cold and extreme temperature fluctuations.
Chopped up straw is normally used to mulch strawberries. This mulch is then removed in early spring. After the plants have leafed out in spring, many farmers and gardeners choose to add another thin layer of fresh straw mulch under and around the plants.
In midwinter, fluctuating temperatures can cause the soil to freeze, thaw, and then freeze again. These temperature changes can cause the soil to expand, then constrict and expand again, over and over. When soil moves and shifts like this from repeated freezing and thawing, strawberry plants may be heaved out of the soil. Their crowns and roots are then left exposed to the frigid temperatures of winter. Mulching strawberry plants with a thick layer of straw can prevent this.
It is commonly believed that strawberry plants will produce a higher yield in early summer, if they are allowed to experience the first hard frost of the previous autumn. For this reason, many gardeners hold off until after the first hard frost or when soil temperatures are consistently around 40 degrees F. (4 C.) before mulching strawberries.
Since the first hard frost and consistently cool soil temperatures happen at different times in different climate zones, we often get those vague answers of “when the foliage turns red” or “when the leaves flatten” if we ask advice on when to mulch strawberry plants. Actually, the latter answer, “when the foliage flattens,” is perhaps the best rule of thumb for when to mulch strawberries, as this only happens after the foliage has experienced freezing temperatures and the plant roots have stopped exerting energy into the aerial parts of the plant.
Foliage on strawberry plants may begin to turn red as early as late summer in some areas. Mulching strawberry plants too early could result in root and crown rot during wet periods of early autumn. In spring, it is also important to remove the mulch before spring rains also expose the plants to rot.
A fresh, thin layer of straw mulch may also be applied around strawberry plants in spring. This mulch is spread under the foliage at a depth of only about 1 inch (2.5 cm.). The purpose of this mulch is to retain soil moisture, prevent splash back of soil borne diseases, and keep the fruit from sitting directly upon bare soil.