Strawberry plants enter a natural state of dormancy in temperate climates as a survival mechanism against cold winter temperatures. This period of rest is necessary for the plant to conserve energy and prepare for a robust spring growing season. While the foliage may appear to be dying, the plant is undergoing a process of internal hardening. This dormant phase allows the plant to withstand freezing conditions that would otherwise cause cellular damage.
Visual Appearance During the Dormant Phase
The first noticeable change in a strawberry plant as it enters dormancy is the transformation of its foliage after the initial hard frost. The vibrant green leaves begin to lose their color, often turning shades of reddish-purple, bronze, or brown before eventually dying back. This visual change indicates that the plant is redirecting its energy away from above-ground growth and into its central survival structure.
The dead or dying leaves typically become dry and crispy, lying flat against the soil surface. This remaining foliage offers a small degree of natural insulation to the plant’s core. The most important part of the plant that remains is the crown, a short, woody structure located at or just below the soil line.
The crown is the compressed stem of the plant, containing the buds for the next season’s leaves and flowers. It remains visible as a low, dense mass and requires protection throughout the winter, as it houses the potential for the next season’s fruit production. The plant’s overall profile is drastically reduced compared to its summer form, which can sometimes lead gardeners to mistake the dormant plant for a dead one.
How Strawberry Plants Survive Freezing Temperatures
The ability of a strawberry plant to endure sub-freezing temperatures is due to a physiological process called cold hardiness or acclimation. As temperatures drop consistently in the fall, the plant ceases top growth and initiates internal changes. This includes minimizing the water content in its most sensitive tissues, a form of natural dehydration that prevents ice crystals from forming inside the cells.
A complex mechanism involves the conversion of starches, the plant’s stored carbohydrates, into soluble sugars. These sugars act as a natural antifreeze, lowering the freezing point of the plant’s cell sap and protecting against cellular damage. This sugar accumulation is concentrated within the crown, enabling this part of the plant to withstand temperatures that would kill non-acclimated tissue.
The crown of a fully hardened, dormant strawberry plant can survive temperatures as low as 20°F (-6.7°C) without external protection. Without insulating snow or mulch, temperatures consistently dropping below 15°F (-9.4°C) can cause significant crown damage, potentially killing the flower buds. The root system remains minimally active, drawing on stored energy reserves within the crown until warmer temperatures return.
Practical Steps for Winter Protection
To ensure the crown survives the winter, gardeners should prepare their strawberry patch after the plants have fully entered dormancy. Waiting until the first few hard frosts is important, as applying protection too early prevents the necessary cold-hardening process. The best time to apply winter protection is when daytime temperatures consistently remain in the 20s and the top inch of soil has frozen solid.
Before applying insulation, clean up the planting bed by removing any old or diseased foliage to reduce the risk of pests and pathogens overwintering. If the autumn has been dry, a thorough watering before the ground freezes helps stabilize the soil temperature and prevent the roots from drying out. The primary method of protection is the application of a loose, airy mulch over the entire planting area.
Clean wheat straw is the most commonly recommended material because it provides excellent insulation without smothering the plant crowns. Other suitable options include pine needles or salt marsh hay. The mulch should be applied loosely to a depth of 4 to 6 inches over the rows, which will compress to a protective layer of 2 to 3 inches.
This thick layer insulates the crown from extreme cold and prevents soil heaving. Soil heaving is a process where the freeze-thaw cycle pushes the crowns out of the ground, exposing the roots to dry air.