Lavender is a fragrant, silver-leafed perennial valued for its calming aroma and dense, mounding habit. To ensure the plant’s longevity and a robust display of flowers in spring, specific winter preparation is necessary. This preparation includes annual pruning, which maintains the plant’s health and prevents it from becoming woody and sparse.
Understanding the Timing and Purpose of Winter Pruning
The ideal time for major pruning depends on the local climate, as the plant needs time to recover before a hard freeze. In milder regions, a substantial trim can be performed in late fall, six to eight weeks before the first expected frost, after the final flush of flowers. In colder zones, it is safer to wait until late winter or very early spring, just as new growth emerges, to avoid exposing fresh cuts to deep freezes. Pruning while the plant is dormant stimulates new, healthy growth from the base once the weather warms.
The primary goal of this trim is to prevent the semi-woody shrub from becoming “leggy,” where it develops thick, unproductive woody stems at the center. Woody stems produce fewer flowers and are prone to splitting or breaking under the weight of snow or ice. Removing a portion of the current season’s soft growth maintains a compact, rounded shape and encourages denser foliage, where next year’s blooms will form. Regular pruning also improves air circulation, which helps prevent fungal diseases during winter wetness.
Essential Tools and Preparation
Before making any cuts, ensure you have the right equipment. A sharp, clean pair of bypass hand pruners is the best tool, as they make clean cuts that heal quickly. Larger, neglected plants may require loppers for thicker stems. Cleaning the blades with rubbing alcohol or a mild bleach solution before and after use prevents the spread of pathogens.
Preparation involves identifying the different types of wood: old wood versus new growth. New growth is the soft, flexible, green or grayish-green foliage from the current season. Old wood is the hard, brown, woody base of the plant that will not produce new growth if cut. Locate the point where the green growth meets the brown, woody base, as this line determines the lowest safe cutting point.
Step-by-Step Pruning Techniques
Begin by removing any dead, broken, or crossing branches, cutting them back to the base or to a healthy, outward-facing bud. Dead stems are brittle and snap easily, helping distinguish them from live, flexible stems. This initial cleanup removes material that could harbor disease or pests over winter.
The general rule for main pruning is to cut back the soft, green growth by about one-third to two-thirds of its length, aiming for a rounded or dome shape. The cut should be made into the green or soft gray foliage, leaving at least one to two inches of green leaves above the woody base. Cutting lower into the old, brown wood can severely damage the plant, as lavender does not reliably regenerate growth from those older sections.
For severely woody and neglected plants, a more aggressive rejuvenation prune can be attempted over two to three years. In the first year, only prune one-third to one-half of the plant back hard, allowing the remaining sections to recover and put out new growth. English lavender (Lavandula angustifolia) tolerates a harder prune than French or Spanish varieties. Consistent annual pruning is the best way to avoid this intensive restoration.
Protecting Lavender During Winter
Once pruning is complete, focus shifts to protecting the plant from cold and excessive moisture. Lavender is highly susceptible to root rot and needs very little water in its dormant state. Established plants typically receive enough moisture from natural rainfall and snowmelt. Watering should only occur if there is a prolonged dry spell.
Protection from extreme cold and freeze-thaw cycles is achieved through proper mulching, which insulates the roots and stabilizes soil temperature. Apply a layer of dry, lightweight mulch, such as pine needles or straw, around the base of the plant. Keep the mulch two to three inches away from the crown of the plant to prevent moisture accumulation against the stems, which leads to rot. In areas with harsh wind, temporary barriers made of burlap can be installed to shield the plant from windburn and desiccation.