Strawberries and raspberries are among the easiest fruits to grow in the home garden. Strawberries are productive for three to five years, while a well-tended raspberry patch may produce fruit for 15 to 20 years. Depending on the variety, strawberries and raspberries are cold hardy to U.S. Department of Agriculture plant hardiness zones 3 or 4, but they do need some protection during harsh winters. If you live north of zone 6, a few simple steps will ensure that your plants survive to see the next spring.
Protecting Strawberries from Frost
When to Mulch Strawberries
Strawberry plants tolerate light frosts, but the plants and flowers are easily damaged by heavy frosts. To protect plants, cover them in the fall with a 3- to 5-inch layer of weed-free straw. Hay usually has more weed seeds and should be avoided as a mulch. Wait until after the first heavy frost to apply a mulch. If you mulch heavily while the plants are still actively growing, you may smother them. If you wait too long, the plants may sustain winter damage. If you don’t have access to straw, try pine needles or shredded leaves. Shred the leaves very finely, though, so they don’t mat when damp and smother the plants.
Removing the Mulch from Strawberry Plants
Slowly remove the mulch in the spring as the ground thaws and new growth appears. Leave the mulch nestled around the base of the plants until mid-spring. Then, as the strawberry plants begin to take off, move the mulch completely off the plants, and set it in rows next to the plants. Do not discard it yet, though. If a late spring storm threatens, cover the plants back up. If the plants freeze now, you’ll lose the berries.
Choosing Strawberry Plants
A well-timed mulch can mean the difference between rotting, frozen plants and a plentiful harvest, but proper variety selection can help, too. June-bearing berry varieties produce large quantities of high-quality fruit, but because they only produce one crop in early summer, they are vulnerable to failure due to late spring freezes. If you live in an area that frequently freezes after April, consider planting an everbearing or day-neutral variety instead. These types produce smaller harvests, but they produce throughout the summer and early fall. If the first harvest is nipped by a spring frost, you won’t forfeit the entire crop.
Protecting Raspberries from Frost
How you protect raspberries depends mainly on the type of berries you grow. Floricane raspberries produce berries in summer on canes that are two years old. After the harvest, remove the 2-year-old canes that produced berries that season. Cut the 1-year-old canes back to 3 feet high. When late fall arrives, bend the young canes gently to the ground and mound 3 inches of soil over them. The soil will insulate the canes and protect them from winter damage. Slowly remove the soil in the spring.
In places with extremely cold temperatures, primocane raspberries are usually a simpler option. These plants produce a summer crop of berries on old canes and a fall crop of berries on new canes. To preserve both crops, cover young canes with soil in the fall as you would floricane berries. A simpler approach though, is to cut down all the canes every year after harvest, allowing only new canes to emerge each spring. You’ll sacrifice the summer crop, but you’ll have a bigger crop in the fall, without the hassle of providing winter protection.
Want to learn more about protecting raspberries and strawberries in winter?
Growing Strawberries from Capitol District Community Gardens
Raspberries for the Home Garden from Colorado State University Extension