Lavender is a popular, fragrant shrub cherished for its aromatic foliage and beautiful flower spikes. Although it is a hardy plant, consistent annual pruning is necessary to maintain a dense, attractive mounded shape. Regular maintenance prevents the plant from becoming leggy and woody, which ultimately reduces the abundance and quality of its blooms. Proper timing of the main structural cut and lighter trimming throughout the season leads to robust growth and longevity.
The Main Pruning Windows for Structural Shaping
The most significant annual pruning establishes the plant’s overall shape and encourages future dense growth. This cut is typically performed after the main flowering period. For most popular varieties, such as English and French lavenders, the optimal time is late summer or early autumn. Pruning at this time allows the plant to heal and produce new growth that can harden off before cold weather arrives.
The goal of structural pruning is to remove between one-quarter and one-third of the plant’s green, leafy growth. This reduction encourages lower branching, preventing the plant from becoming hollow and woody in the center. Complete this major cut at least four to six weeks before the area’s first expected hard frost. Pruning too late leaves vulnerable stems susceptible to cold damage, often resulting in dieback over winter.
A second option for structural shaping is early spring, just as the first signs of new growth emerge at the base of the plant. This timing is useful for regions with severe winters or if late summer pruning was missed. Waiting until new growth appears provides a visual cue for where to cut, ensuring the removal of old material without damaging new buds. However, spring pruning must be done before the plant puts significant energy into flowering, or it may delay the bloom time for that year.
Mid-Season Care and Deadheading
Beyond the major annual structural cut, lavender benefits from lighter, more frequent trimming throughout the growing season. This practice is known as deadheading, which involves removing spent flower spikes as soon as they fade. Deadheading is an ongoing task that prevents the plant from diverting energy into seed production.
Removing the withered flower heads signals the plant to focus resources on producing new vegetative growth and often a second flush of blooms. This lighter trimming should be performed immediately after a flower spike has lost its color and fragrance. Snip off the spent flower head along with a few inches of the attached stem, cutting above a set of healthy leaves.
This mid-season care maintains the plant’s tidy, mounded appearance and optimizes its blooming potential. French and Spanish lavenders, which often produce multiple waves of flowers, benefit the most from continuous deadheading.
Technique: Avoiding Cuts into Old Wood
A foundational rule for all lavender pruning is the strict avoidance of cutting into old wood. Old wood is the gray, brittle, non-flexible base of the plant that lacks the necessary dormant buds to regenerate new shoots. Cutting into this lignified tissue invariably results in a bare stub that will not sprout new foliage or flowers.
To ensure successful regrowth, the pruning cut must always be made into the soft, green, leafy portion of the stem. The correct cutting point is just above a visible cluster of leaves, which are the active growth points. Leaving several sets of leaves on the stem above the old wood guarantees the plant can produce new, healthy growth from the remaining structure.
While the principle remains consistent, English lavender is less tolerant of deep cuts than Spanish or French types. Rejuvenation pruning, which involves cutting the plant severely back into the woody base, is a high-risk measure reserved only for severely overgrown plants. This extreme cut should only be attempted in early spring, understanding that the plant may not recover and might require replacement. For routine maintenance, sticking to the green, flexible growth ensures the plant remains dense and vigorous.