Strawberry plants, fruit-bearing perennials, require winter care to ensure a successful harvest the following season. In regions where temperatures regularly drop below freezing, providing a protective covering is necessary to safeguard the plant’s crown and shallow root system. The crown, the compressed stem base where the leaves and flower buds originate, is susceptible to damage from extreme cold, especially temperatures sustained below 15°F (-9°C). Protecting the plants also minimizes the damaging effects of freeze-thaw cycles, which can cause soil heaving that pushes roots out of the ground, exposing them to cold air and desiccation. Proper timing and method for applying this winter protection are directly linked to survival and subsequent productivity.
Preparing Plants for Dormancy
Gardeners must perform specific maintenance in late fall to ready the strawberry patch before any cover is applied. This preparatory work begins with a thorough cleaning of the bed, removing old leaves and debris that can harbor fungal diseases or overwintering pests. Clearing this material prevents moisture from being trapped against the crowns, which could lead to rot during the dormant period.
The plants must then be allowed to enter a natural state of dormancy, known as “hardening off.” This biological change is triggered by shortening daylight hours and the gradual decrease in temperature, causing the plant to slow its growth and prepare for cold. Ensuring the plants are adequately watered before the ground freezes is important, as the crown needs sufficient moisture reserves to prevent drying out during the winter.
Determining the Right Time to Apply Cover
Applying mulch too early can be detrimental, so the timing should not be rushed. The plants must be fully dormant before covering, which usually happens after several hard frosts. Covering plants that are still actively growing can trap warmth and moisture, potentially encouraging rot or premature, weak growth that will be damaged by the later winter cold.
A reliable indicator for timing is the soil temperature, which should consistently be below 40°F (4°C) at a depth of four inches. This temperature confirms the plant has completed its hardening process and is safely dormant. Air temperature provides a guideline, with the ideal moment arriving when nighttime temperatures have consistently dropped into the low 20s F (-4 to -6°C) for several nights.
It is important to apply the cover before the ground freezes solid, as the mulch helps regulate the soil temperature and prevents deep freezing. A loose, insulating layer needs to be in place before temperatures drop below 20°F (-6°C), a point where crown and flower bud damage becomes a significant risk. Timing the application between the plant’s dormancy and the onset of severe, sustained cold is necessary to maximize winter survival and subsequent yield.
Choosing and Applying Winter Protection
The chosen material for winter protection should be insulating yet breathable, allowing air exchange to prevent moisture buildup and the development of mold or disease. Clean, weed-free wheat or oat straw is the most widely recommended material because it provides excellent insulation without excessively compacting. Other options include pine needles or specialized agricultural row covers, but materials like leaves or grass clippings are unsuitable.
Straw should be applied loosely and evenly over the entire strawberry bed, covering both the plants and the surrounding soil. The initial depth should be approximately 4 to 6 inches of loose material. This layer will naturally settle over the winter, ultimately reducing to a protective thickness of about 2 to 3 inches.
Securing the cover is important in areas prone to wind, as a compromised layer reduces insulation. Methods for anchoring the material include laying wire fencing or netting over the straw, or securing the edges with rocks, bricks, or soil. Throughout the winter, the patch should be checked periodically, and additional straw should be added if the cover becomes too thin or shifts away from the crowns.
Removing Protection in the Spring
The process of removing the winter cover in spring needs to be timed carefully to protect the plants from late frosts while allowing them to resume growth. The gardener should begin removing the bulk of the mulch when consistent daytime temperatures remain above freezing and the threat of severe hard frost has largely passed. A good indicator is when new growth emerges under the cover or when the soil temperature at a four-inch depth reaches 40°F (4°C).
Removal should be gradual, typically achieved by raking the heavier layer of straw off the plants and into the aisles between the rows. This partial removal allows the plants to slowly re-acclimate to the cold air and light, preventing shock. The remaining thin layer of straw left directly around the crowns serves a double purpose: it suppresses weeds and keeps developing berries clean by preventing contact with the soil.
Leaving a portion of the straw in the aisles is strategic, as it remains available for quickly covering the plants again should a late spring frost be predicted. Delaying the full removal of the cover for too long can be detrimental, encouraging crown rot or delaying flowering and subsequent harvest. The goal is to balance protection from cold with the need for light and air to encourage vigorous spring growth.