Strawberry plants are perennials that survive cold months by entering a period of winter dormancy, triggered by shorter daylight hours and cooler temperatures. Proper preparation for this phase ensures the health of the plant and maximizes the subsequent year’s harvest yield.
The primary focus of winter care is safeguarding the crown, the compact, centralized growing point of the plant. Damage to the crown from repeated freezing and thawing cycles or extreme cold can prevent new growth or kill the plant. Successful overwintering ensures the plant has sufficient stored energy for spring flowering and fruiting.
Preparing the Plants for Dormancy
The process of readying strawberry plants for winter should begin in late autumn, well before the first sustained hard frost arrives. This practice, often called “renovation,” focuses on clearing the bed and redirecting the plant’s energy reserves. Older, mature foliage should be trimmed back to about one inch above the crown. This trimming helps reduce the surface area where fungal diseases might otherwise establish and overwinter.
During renovation, any long, trailing runners—the horizontal stems that propagate new plantlets—should be clipped off. These runners drain energy from the main mother plant that would be better used for building up carbohydrate reserves in the crown for winter survival. Clearing the bed of all this debris, along with any persistent weeds, reduces the likelihood of pests and pathogens carrying over.
Once renovation is complete, the plants require a final, deep watering. This deep soak ensures the soil holds sufficient moisture before the ground freezes solid. Adequate soil moisture insulates the roots and the crown, providing a buffer against early winter temperature fluctuations.
This pre-freeze hydration is the last opportunity to supply water until the spring thaw, as frozen soil prevents absorption. A well-hydrated crown is more resilient to the stresses of cold and desiccation during dormancy.
Protecting In-Ground Strawberry Beds
After the plants have been prepared and experienced several hard frosts, apply a protective insulating layer, or mulch, to the entire bed. The purpose of mulching is to maintain a consistent soil temperature, not primarily to add warmth. Preventing the soil from repeatedly freezing and thawing is paramount, as these cycles can heave the plants out of the ground, exposing vulnerable crowns and roots.
Mulch should be applied only after the plants are fully dormant and the top inch or two of soil has lightly frozen. Applying it too early can trap warmth, signaling the plants to break dormancy prematurely and making them susceptible to later cold snaps. Waiting until the ground has just begun to freeze ensures the plants are completely dormant.
Suitable materials are light, airy, and do not compact easily, preventing crown suffocation. Clean straw is preferred due to its high loft, though pine needles or shredded, dry leaves also work effectively. Avoid heavy materials like grass clippings or sawdust, which can matte down and hold too much moisture, potentially leading to rot or mold.
The insulating layer should be applied to a uniform depth of four to six inches over the entire bed, completely covering the crowns. This depth provides sufficient thermal mass to slow the rate of temperature change in the soil beneath. The mulch should also extend several inches past the edges of the planting area.
This heavy layer remains in place throughout the coldest months. It should only be removed gradually in the spring when new growth begins to emerge, allowing the crowns to acclimate slowly to warmer temperatures.
Overwintering Potted and Container Plants
Strawberry plants in containers require different winterization strategies because their roots are more vulnerable to cold exposure than in-ground plants. The soil mass in a container is exposed to cold air on all sides, causing the temperature to drop faster and lower, potentially freezing the roots solid.
A simple first step is to group all containers closely together against a sheltered wall for protection from cold winds and temperature swings. For regions with consistently freezing winters, more substantial protection is necessary to prevent repeated freezing and thawing.
The most effective method is to bury the pots entirely into the ground in a garden bed or deep cold frame. Burying mimics the insulation of an in-ground bed, keeping the roots at a stable, slightly warmer temperature.
Alternatively, containers can be moved into an unheated garage, shed, or basement. Temperatures should remain consistently low but above freezing, ideally between 25 and 40 degrees Fahrenheit, to prevent deep freezing while maintaining dormancy.
Even when sheltered, container plants can suffer from desiccation due to winter winds or dry air. They require minimal watering, perhaps once or twice a month, just enough to prevent the root ball from becoming completely arid. The soil should never be saturated, as overly wet soil in cold temperatures leads to root rot and fatal freezing.
Gardeners in mild climates may only need temporary shelter during brief, intense cold snaps. Those facing harsh, long winters must commit to a full insulation strategy, ensuring the crowns and roots are continuously protected until spring.