Strawberries, Fragaria × ananassa, are flat, fruit-bearing perennials suitable for growing in USDA hardiness zones 3 through 10.
People in cold regions with freezing winters, which are sometimes viewed as challenging crops, often grow plants as annuals and discard them at the end of the season.
However, if you pick the toughest varieties and offer a little TLC before winter, your favorite berry makers can deliver sweet and savory treats year after year.
Our comprehensive guide to growing strawberries has everything you need to know about planting, caring for, and harvesting strawberries.
In this article, we're going to focus on a few simple steps to winterize plants so they will come back vigorously each spring.
Here is the lineup:
There's a chill in the air. Let's start!
Most strawberry varieties require 200-300 hours of cooling with temperatures between 45 and 32 degrees F for optimal fruit production.
According to Emily Hoover, a horticulturalist at the University of Minnesota Extension, Temperatures of 15 ° F or below can fatally damage the crown.
If you live in an area where the ground freezes in winter, your strawberries will benefit from some proactive measures to help them get through the coldest months of the year.
There are four reasons for this:
- To avoid damage to the next spring's buds.
- Minimization of root damage due to temperature fluctuations through repeated freezing and thawing.
- In order to prevent the "lifting", a spontaneous uprooting is postponed, which is caused by ground shifts during freezing and thawing.
- To maintain the moisture needed to prevent crowns – the part of the plant that the stems come from – from drying out.
With a little preparation, you can protect your plants from the ravages of winter and set them up for a healthy return from their dormant period.
Contained plants can be made using the methods described below and then placed in a basement, shed, or garage to survive the winter.
Four easy steps
The four steps to preparing strawberries for winter are: renovating, fertilizing, watering and applying mulch.
Let's take a closer look at each step:
1. Renovate your plants
There are three types of strawberry plants:
- June-bearing varieties that bud in fall, bloom in spring, and produce a large harvest, typically in June.
- Everlasting varieties that bud on long days and produce three harvests each year.
- Daily neutral varieties that bloom and bear fruit throughout the growing season, provided temperatures are not below 35 ° F or above 85 ° F.
After the fruits are harvested, plants that are expected to hibernate need renovation. This process consists of pruning foliage, thinning it, and removing dirt and weeds.
For June varieties, you'll need to prune the foliage to a height of 1 to 2 inches above the crown. You can do this with loppers or hedge trimmers.
If you have a large, flat field of strawberries, you can also use a lawn mower with the blade set to the correct height. However, do not mow for more than a week after the last harvest, otherwise you could damage the new leaves.
Thin plants that have spread and matted into rows eight to twelve inches wide, with two to three feet between them.
Remove the runners as needed to bring your plants to their target width. You can use a tiller for this task.
If they don't grow in rows, thin them down to five per square foot, or about four to six inches apart.
Discard any that have been weakened by adverse weather conditions, disease, or pest infestation.
Remove weeds and dirt.
For ever-bearing and day-neutral varieties, cut off any leaves that appear damaged, diseased, or infested with pests. If necessary, remove whole plants.
Thin the remaining to five per square foot, or about four to six inches apart.
Remove the runners to prevent new plants from growing and remove weeds and debris.
Dispose of sick and pest-infested leaves in the trash, not on the compost heap.
Outreach gardener Richard Jauron from the Department of Horticulture at Iowa University Extension recommends using a 10-10-10 (NPK) balanced fertilizer at the rate of 5 pounds per 100 feet of row, or 1 pound per 25 plants, at least a month prior to your average first frost date.
Avoid direct contact with foliage, apply granular fertilizer or pellets between plants in beds and containers and in the aisles between rows. Water well.
After you've renovated your plants, keep watering until the first frost. Provide an extra inch of water each week when it doesn't rain.
During the cold months, while they are dormant, there is no need to provide additional watering for those growing in the garden.
Container-grown plants that are placed in a cold shed or garage require little water, just enough to keep the soil from drying out completely.
4. Apply mulch
Mulch is the final step towards winter readiness. The application of mulch provides a layer of insulation, which is particularly important in regions where the insulation of nature is hardly or not at all: snow.
Photo via Alamy.
Covering plants not only helps keep them evenly cold with temperature fluctuations, but also helps maintain the moisture that is important for crown health while promoting optimal drainage.
The application of mulch cannot be accelerated for three reasons:
- Laying too early can increase the floor temperature and encourage new growth.
- It can trap excessive moisture that can rot crowns.
- It can attract mice and other rodents that are still actively seeking winter protection.
The best time to apply mulch is between late November and early December, after the first frost, when much of the foliage is brown and limp, and before temperatures drop below 20 ° F.
As mentioned earlier, plants that aren't covered with mulch or snow are prone to deadly crown damage at 15 ° F.
Choose a mulch material that is loose to prevent matting, facilitate air circulation, and aid in drainage.
Straw or pine needles are excellent choices. Avoid leaves and grass as they are likely to dull, as well as hay as it tends to be full of weed seeds.
Photo via Alamy.
To apply mulch, drop it around and over the plants with loose handfuls. The pieces of straw or pine needles should separate as they fall, forming airy piles rather than tight clumps.
Completely bury any visible foliage under a continuous blanket of mulch, down to the rows or to the edges of the beds, raised beds, or containers.
For those who grow in the garden, the professionals are at Expansion and reach of Iowa State University recommend applying three to five inches of mulch.
They recommend six to eight inches in raised beds, especially pyramid planters, as the soil temperature gets even colder than the soil.
Some people prefer to lay mulch when rain is forecast to keep it in place.
If you are in a particularly windy place, you can anchor the mulch in your rows and beds with chicken wire. You can use bricks, stones, or stakes to hold the chicken wire in place.
Regardless of when you install or anchor it, the mulch will compact over time and you may need to make additional applications over the winter months.
If you grow your strawberries in barrels or pots, you can store them in a cold shed or in an unheated basement or garage. Loosely wrap the containers in burlap and fill the sides and top with six to eight inches of straw.
That's all there is to it. To recap, there are four steps you need to take to prepare your strawberries for the winter rush:
- Renovate after harvest.
- Fertilize with a balanced product.
- Pour an inch a week until the first frost.
- Apply mulch generously and loosely after the first frost.
And then, on a dry day in early spring, after the winter winds stop howling and the snow has finally melted, gently pull back the mulch.
When you see green shoots, it's time to remove the mulch and let them bask in the sunshine. If not, please try again soon.
What should you do with the mulch?
Rake it in the aisles between the rows to soak up the spring rain and make walking less muddy. Leave something tucked around the sprouts to inhibit weeds, aid in moisture retention, and keep future berries out of dirt.
Keeping mulch close is also handy when a late-season frost threatens to provide short-term protection in an emergency.
We hope that wintering will soon be a routine part of strawberry care in your garden, so that you can get through the cold months with confidence and keep berrying!
Have you successfully overwintered your strawberry plants? Share your tips in the comments below.
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About Nan Schiller
Nan Schiller is a writer with deep roots in the soil of southeastern Pennsylvania. Her background includes landscape and floral designs, a BS in business from Villanova University, and a Certificate of Merit in floral design from Longwood Gardens. As an advocate of organic horticulture with native plants, she always has dirt under her nails and freckles on her nose. With wit and hopefully some wisdom, she shares what she has learned and is always ready to delve into a new project!