By: Darcy Larum, Landscape Designer
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 mid-winter, 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 F. (4 C.) before they mulching strawberries.
Because 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.
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Read more about Strawberry Plants
How To Prepare And Protect Your Strawberry Plants For Winter!
Winter is just around the corner, and that means it’s time to start preparing and protecting your strawberry plants for a long winter’s nap!
Whether you grow strawberries in the garden, raised beds, or pots and containers – they need protection from winter’s fury. Not only for their survival, but for strong growth and production next year too.
To get your strawberries to come back strong in the spring, it is important to put them to bed properly this fall.
But how you protect them correctly depends on two important factors.
The first is knowing which variety you grow – June bearing or everbearing? While the second depends on where and how you grow your strawberries – whether it be in a garden setting, raised bed, or in containers.
With that in mind, here is a in-depth look at how to properly protect your strawberry plants. No matter how or what variety you grow!
When should I remove the mulch on my strawberry bed?
When should I remove the mulch on my strawberry bed?
To reduce the chances of crop damage from a late frost or freeze, leave the mulch on as long as possible. Removing the mulch in March may encourage the plants to bloom before the danger of frost is past. Temperatures of 32 degrees Fahrenheit or lower may severely damage or destroy open flowers. Since the first flowers produce the largest berries, a late spring frost or freeze can drastically reduce yields.
To determine when to remove the mulch, periodically examine the strawberry plants in spring. Remove the mulch from the strawberry planting when approximately 25 percent of the plants are producing new growth. New growth will be white or yellow in color. (If possible, the winter mulch on strawberries should remain until mid-April in central Iowa.) When removing the mulch, rake the material to the aisles between rows. If there is a threat of a frost or freeze later in spring during bloom, lightly rake the mulch over the strawberry plants.
Program Specialist, Horticulture
Iowa State University Extension & Outreach
While it may seem a little odd to be dreaming of fresh strawberries on a cloudy, cool November day in Iowa, those delicious thoughts are an excellent incentive. To insure a bountiful crop next year, home gardeners need to mulch their strawberry plantings in the fall.
Cold winter temperatures and repeated freezing and thawing of the soil through the winter months are the main threats to the strawberry plants. Temperatures below 20 degrees F may kill flower buds and damage the roots and crowns of unmulched plants. Plants also can be destroyed by repeated freezing and thawing which can heave unmulched plants out of the soil.
Strawberries should be mulched in the fall before temperatures drop below 20 degrees F. However, allow the strawberry plants to harden or acclimate to cool fall temperatures before mulching the planting. Plants mulched before they have properly hardened are actually more subject 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. The depth of the mulch should be three to five inches at application. The material should eventually settle to two to four inches.
In windy, exposed areas, straw mulches can be kept in place by placing boards or wire 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. A leaf mulch may damage plants due to excess moisture trapped under the material.
The winter mulch on strawberries should remain in place until plants show signs of growth in the spring. Do not remove the mulch in March. Early removal of the mulch may encourage plants to bloom before the danger of frost or freezing temperatures is past. A late frost or freeze could damage or destroy open flowers and substantially reduce yields. The first flowers are especially important as they produce the largest berries.
To determine when to remove the mulch, periodically examine the plants under the mulch during periods of warm weather in spring. Remove the mulch from the strawberry planting when about 25 percent of the plants are producing new growth. New growth will be white or yellow in color. If possible, the winter mulch on strawberries should remain until mid-April in central Iowa. When removing the mulch, rake the straw to the aisles between rows. If there is a threat of a frost late in the season during bloom, the mulch can be lightly raked back over the strawberry plants.
Although mulching strawberries isn't much fun, consider the tasty rewards. Strawberries and ice cream, strawberry shortcake, and strawberry cheesecake are a few of the rewards that await the dedicated gardener.
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The North Carolina 4-H Grow For It program provides resources and opportunities to connect youth and educators to issues in agriculture and natural resources in meaningful ways. This initiative is striving to grow a generation of youth interested in investigating plants, insects and soils through experiential projects that fosters curiosity and wonder, inspire critical thinking and problem solving, build a positive science self-concept, connecting kids to good food and nurturing environmental stewards of the land through farm, garden and nature programming. This programming includes camps like the Resource Conservation Workshop or the Horticultural Science Summer Institute and contests like the state fair insect collection, honey bee essay and horticulture identification and judging contest.
Through the infrastructure of the North Carolina Cooperative Extension system, adult leaders are supported through curriculum development, resource materials, and training workshops to build their knowledge, enthusiasm and ability to deliver research-based programs for youth.
Liz Driscoll is the 4-H subject matter specialist that leads the Grow For It program. Liz loves tromping around gardens, woods, swamps and beaches, exploring interesting plants, soils and bugs and sharing their stories. Her favorite activities include grazing in the garden, stalking interesting insects, whispering secrets to snapdragons and building sand castles.