June-bearing, everbearing, and day-neutral strawberries can all be grown as perennials in most areas. However, if you want your strawberry plants to come back in spring and fruit abundantly, you need to provide the plants with proper autumn care and winter protection. This guide covers how to fertilize, renovate, and winterize strawberry plants in garden beds and containers so you can grow a lush crop of strawberries year after year.

Why Winterize Strawberries?

Most strawberry plants can technically overwinter in growing USDA Zones 4 and warmer. However, extreme cold temperatures can prove fatal to strawberry plants if they don’t have extra winter protection. During winter, the soil freezes and thaws repeatedly, which can heave strawberry crowns out of the soil and damage delicate plant roots.

Winter damage also severely limits the size of strawberry harvests because many strawberries form the buds for their fruit in the summer or fall of the previous year. However, when temperatures drop very low during winter, those strawberry buds can be damaged and not produce fruit when the plant leafs out in spring.

When to Winterize Strawberries

Winterizing strawberries begins in summer with renovation and fertilization of the plants after fruiting ends. Mulch or other winter protection is usually added to strawberry plants much later in the season, after the first frost of fall.

When winterizing strawberries, it’s important to time the mulch application properly. Mulching strawberries too early can cause plants to rot or not harden off properly, leaving them vulnerable to cold damage. Extreme cold may damage the plants if they are mulched too late in the season.

In most areas, the best time to mulch or winterize strawberries is in November or early December, when daytime temperatures are consistently in the 20s, and the top 1 inch of soil is frozen. In areas with mild climates, you may want to add mulch around strawberries when the temperature drops into the 40s. You’ll know it’s time to mulch when the strawberry leaves turn brown and are floppy.

How to Winterize Strawberry Plants

In mild areas, strawberries may be able to overwinter without extra protection, but the plants will be healthier and fruit better if you prepare them for the winter season ahead. Regardless of the type of strawberries you grow, these three steps will help ensure your strawberries survive the cold and emerge in spring ready to produce lots of luscious fruit.

Step 1: Renovate

Strawberries can become overgrown, develop broken stems, or encounter diseases or pests throughout the growing season. It’s wise to renovate strawberry plants after they’re done fruiting, in late July to early August.

To renovate June-bearing strawberries, prune away any broken or damaged leaves on the plants, and then cut the strawberry plants down to about 1 ½ inches above the plant’s crown. If you have a large patch of strawberries, cut them back with your lawnmower. Be sure to cut strawberries no later than a week or two after they’re done fruiting, as you don’t want to damage their new, developing leaves. If the plants are tightly matted, thin out the strawberry plants and runners so they are spaced at least 4 to 6 inches apart.

For everbearing or day-neutral strawberries, prune away any dead or damaged leaves and pull out any weeds that have crept into your strawberry patch.

Step 2: Fertilize

After renovating the strawberries, most growers recommend applying a slow-release, balanced, granular fertilizer to strawberry plants in the fall, about one month before your first frost date. This ensures the strawberries have all the nutrients they need to grow and fruit the following season.

While it’s always wise to consult the fertilization instructions on the fertilizer packaging, in general, apply about 1 pound of fertilizer for every 25 strawberry plants.

Step 3: Mulch

Water the strawberry plants until the first frost, but when temperatures drop, it's time for mulch.

Mulching protects strawberry crowns from extreme cold and insulates the soil so that the plant roots won’t be subjected to much freezing and thawing. A thick layer of mulch also locks moisture into the soil, limiting the need to water strawberry plants in winter.

The best time to mulch strawberries is usually in November or December when plants are starting to go dormant. Select a lightweight, natural mulch, like salt marsh hay, pine needles, or weed-free straw, and loosely mound the mulch over the tops of the strawberry plants, covering all the leaves with about 3 to 5 inches of mulch. Steer clear of heavy mulches, like chopped autumn leaves or grass clippings, as these mulches become too dense when wet and reduce airflow around the strawberry plants.

If you don’t want to work with mulch, you can also spread frost protection covers over strawberry plants. However, these covers can cause strawberries to leaf out earlier in spring, so you might need to add extra spring protection to your plants if you use fabric row covers.

Leave the mulch and frost protection covers on the strawberry plants until spring when the plants begin to leaf out. Once you see those first green shoots emerging, pull away the mulch and use it to suppress weeds in your garden or in the rows between your strawberry plants. Keep a bit of mulch on hand in case a late spring frost occurs and you need to briefly cover the strawberry plants again.

How to Winterize Strawberries in Pots

Winter care for strawberries growing in pots is similar to caring for strawberries in the garden. Renovate and fertilize the plants after they’re done fruiting, and apply mulch. However, container-grown strawberries need extra protection to get them through the winter.

Gardeners in mild climates may be able to keep potted strawberries outdoors all year round. However, if you live in a cooler area, you may want to bring potted strawberries into a sheltered spot, like a potting shed or garage, after the plants enter a dormant state in the fall. To protect the plants and pots, wrap old blankets, burlap, or packing material around the strawberry pots and then loosely mound 6 to 8 inches of straw or pine needles over the plants.

Because strawberries are dormant during the winter months, they don’t need much water, but lightly water potted strawberries about once a month during the winter to keep them from completely drying out.