Lavender (Lavandula) is a sun-loving subshrub native to the dry, rocky Mediterranean basin, meaning it is adapted to lean soil and arid conditions. Its survival in cooler climates depends not only on protection from extreme cold but, more importantly, on shielding it from excessive winter moisture. The plant’s primary vulnerability is a combination of freezing temperatures and wet soil, which quickly leads to lethal root rot. Proper winterizing focuses on mimicking its native dry environment to ensure the woody crown remains healthy through dormancy.
Preparing Lavender for Winter Dormancy
Preparation for winter begins in late summer or early fall, typically about six weeks before the first hard frost is anticipated. This timing allows the plant to slow its growth and harden off before temperatures drop significantly. Gardeners should perform only a light, cosmetic pruning to shape the plant and remove any remaining spent flower stalks, known as deadheading. Avoid a severe cutback in the fall, particularly in colder regions, as this exposes the woody stems to harsh winter winds and moisture damage; the major shaping prune should be reserved for the spring.
Protecting In-Ground Lavender from Cold and Moisture
For established plants in the ground, the goal is to enhance drainage and insulate the root zone without trapping moisture around the plant’s crown. Use an inorganic, coarse-textured mulch like crushed gravel, pea stone, or coarse sand, as these materials allow water to drain quickly while reflecting sunlight to warm the soil. Apply a two-to-three-inch layer around the base of the plant in late fall, ensuring it is kept a few inches away from the central woody crown. Piling mulch directly against the stem can trap moisture and invite fungal issues. In areas prone to harsh, drying winter winds, erecting a temporary burlap screen or windbreak can prevent the foliage from dehydrating, a condition known as winter burn.
Strategies for Overwintering Potted Lavender
Container-grown lavender is highly susceptible to cold damage because the soil mass in a pot freezes far more readily and deeply than the ground. Tender species, such as Spanish and French lavender, must be moved to a protected location, while hardy varieties like English lavender can often survive in an unheated garage, shed, or cold frame. The ideal overwintering location is cool and bright, maintaining a temperature range between 40°F and 65°F, and free from drastic temperature swings. Drastically reduce watering frequency throughout the winter, as overwatering is the leading cause of death for potted lavender in dormancy; wait until the top inch of soil is completely dry before providing minimal water, perhaps only once a month.
Spring Transition and Removal of Winter Protection
As the threat of hard frost passes in early spring, begin the process of removing winter protections. Gradually take down burlap screens and rake away any applied mulch to allow the soil around the crown to dry out and warm up. This gradual exposure prevents the plant from being shocked by a sudden change in environmental conditions. This is the proper time for the major annual pruning, which encourages robust new growth and a compact shape. Using clean shears, cut back the plant by roughly one-third of its size, being careful to avoid cutting into the old, completely woody base, as pruning into leafless wood can prevent new shoots from emerging.