Strawberry plants are perennials, meaning they are built to survive cold seasons and return year after year, offering a rewarding harvest for home gardeners. While these plants possess natural cold tolerance, they require specific preparation and insulation to navigate harsh winters, particularly in regions with significant freezing temperatures. Understanding the plant’s biological process and providing targeted protection ensures a healthy patch ready to produce an abundant crop when spring arrives. This preparation focuses on protecting the plant’s survival mechanism and timing the protective measures correctly.
The Strawberry Plant’s Survival Strategy
The strawberry plant survives winter through dormancy, a biological process where above-ground growth shuts down to conserve energy. The true survival point is the “crown,” the short, thick stem located right at the soil surface from which the leaves and roots emerge. This crown contains the buds for the following year’s leaves and flowers, making its protection paramount for future fruit production.
Once temperatures consistently drop in the fall, the plant begins to harden off, preparing its tissues to withstand the cold. Unprotected strawberry crowns can sustain significant damage or even die if temperatures fall below 15 to 20 degrees Fahrenheit. Deep cold tolerance is unlocked only when the crown is insulated, allowing it to survive temperatures potentially as low as negative 20 degrees Fahrenheit. The goal of winterizing is to preserve the flower buds already set within the crown during the previous fall.
Preparing Plants for Winter Dormancy
The process of preparing the strawberry patch for winter begins long before the first frost, focusing on encouraging the necessary dormancy and sanitation. In late summer, gardeners should stop all nitrogen-heavy fertilization to prevent tender new growth that would be highly susceptible to freezing damage. The plant must instead direct its energy toward fortifying its existing tissues and storing carbohydrates for the winter.
Sanitation
Sanitation is a preliminary step that involves removing old, diseased, or dead foliage from the strawberry patch. This practice minimizes the presence of fungal spores and pest eggs, reducing the likelihood of disease overwintering and infecting the new growth in spring. Removing this debris also ensures that the protective mulch layer applied later can rest directly on the soil and crown without trapping excessive moisture.
Pre-Freeze Watering
The final pre-winter task is to ensure the soil has adequate moisture before the ground freezes solid. A well-hydrated crown is significantly more resilient to cold injury than a dry one, as water within the plant cells helps stabilize tissues. Watering deeply just before the first sustained freeze provides a buffer, helping to regulate the temperature of the soil surrounding the crown throughout the winter months.
Essential Winter Protection
Once the plants have entered true dormancy, typically when nighttime temperatures drop consistently to about 20 degrees Fahrenheit and the topsoil begins to freeze, it is time to apply the protective layer. Timing this application is important; covering the plants too early can prevent them from hardening off properly, while waiting too long risks damage to the exposed crowns. The ideal material for this insulation is clean, loose straw, which provides excellent air pockets for thermal regulation without compacting heavily.
The straw should be applied loosely over the entire strawberry bed at a depth of four to six inches. This thick layer will compress over the winter due to snow and moisture, settling to an effective insulating depth of two to four inches. Materials like leaves or grass clippings should be avoided because they tend to mat down when wet, suffocating the crowns and trapping moisture that can lead to rot.
The insulation serves two primary purposes beyond just protecting against extreme cold. First, it directly shields the crown from lethal low temperatures, preventing the injury of the dormant flower buds. Second, the mulch prevents a phenomenon called “crown heaving,” which is caused by repeated cycles of freezing and thawing soil. Heaving physically pushes the shallow-rooted crowns out of the ground, exposing them to desiccating winds and cold, which the insulating mulch prevents by keeping the soil temperature more stable.
Waking Up the Plants in Spring
The transition out of winter must be managed carefully to avoid damaging the newly emerging tender growth. The protective winter mulch should be removed gradually in early spring when the plants begin to show signs of new growth. This typically occurs when the soil temperature rises consistently above 40 degrees Fahrenheit. An indicator for this timing is when approximately 25 percent of the plants start to push out new, pale green or yellow leaves underneath the straw.
The mulch should not be completely removed from the area; instead, rake most of it into the aisles between the rows or slightly away from the crowns. Leaving a thin layer of straw around the base helps keep berries clean and suppresses weeds during the growing season. Keep the bulk of the removed straw nearby, as a late-season frost can still threaten new blossoms. If a late frost is forecasted, the straw can be quickly raked back over the plants for temporary insulation.