Lavender is a beloved perennial shrub, popular in gardens for its fragrant foliage and spikes of purple flowers. As gardeners look to multiply their plants, a common question arises regarding the best method of propagation, particularly whether established plants can be divided. While division is a time-honored technique for many perennials, it is not universally applicable. This article clarifies why division is rarely the proper choice for lavender and details the far more reliable alternative method of propagation.
Understanding Lavender’s Growth Habit
The question of whether lavender can be divided hinges entirely on its botanical classification and physical structure. Unlike many herbaceous perennials, such as hostas or daylilies, which have fleshy root systems that can be easily split, lavender is categorized as a semi-woody sub-shrub. While its upper growth is soft and new each season, the base of the plant develops a hard, woody crown over time.
This woody base typically contains a single, centralized root structure that is not designed to be severed. Attempting to cut through this woody crown is highly likely to cause irreparable damage and lead to plant death. The large wound created by division is a significant entry point for diseases, and the remaining root mass is often insufficient to sustain the separate sections.
The only scenario where a form of division is possible is with young, sprawling varieties or older plants that have naturally layered. Layering occurs when a lower branch touches the soil and spontaneously develops independent roots, creating a self-rooted offshoot. These rooted side shoots can be carefully severed from the mother plant and transplanted without risking the health of the main shrub. For established, compact plants, attempting to split the main root ball is strongly discouraged due to the plant’s woody, centralized architecture.
The Alternative: Propagating via Softwood Cuttings
Since cutting the main root structure is ineffective, the most successful and least stressful way to multiply lavender is through softwood cuttings. This technique involves taking small sections of the current season’s new growth, which retains the flexibility necessary for root initiation. Softwood cuttings allow the gardener to create new, genetically identical plants without causing any harm to the parent shrub.
Begin by selecting healthy, non-flowering shoots from the lavender plant’s exterior growth. The ideal cutting length is typically between 4 and 6 inches. The cut should be made cleanly just below a leaf node, which is the point where leaves emerge from the stem. Using a sterilized, sharp tool, such as a knife or pruning shears, minimizes damage and prevents the transmission of pathogens.
After taking the cutting, remove the leaves from the lower half to two-thirds of the stem. This prepares the bare stem for insertion into the rooting medium and prevents buried foliage from rotting. Applying a powdered or gel rooting hormone to the cut end is recommended, as it contains auxins that significantly accelerate root formation. The hormone provides a concentrated growth signal, dramatically increasing the success rate.
The prepared cuttings should then be inserted into a well-draining rooting medium. Perlite or coarse sand mixed into standard potting soil is an excellent combination. This gritty mix ensures that excess water drains quickly, which prevents the cuttings from rotting before they establish roots. Gently firm the soil around the base of each cutting to ensure full contact between the stem and the rooting medium.
Optimal Timing and Preparation for Propagation
The timing of propagation influences the success of lavender cuttings. Softwood cuttings are best taken during the period of active growth, typically from late spring through early summer (roughly June through September). During this time, the plant produces new, pliable growth that is metabolically primed for root development.
Cuttings taken during the cooler months, or hardwood cuttings taken from older, woody stems, take longer to root and have a lower success rate. Once planted, they require a warm environment and bright, indirect sunlight to encourage root formation without scorching the foliage. A temperature range of 65 to 75 degrees Fahrenheit is generally considered optimal for stimulating root growth.
The choice of planting medium is linked to the survival of the cuttings. Lavender naturally thrives in lean, well-aerated, and fast-draining soil, and the rooting medium should mimic these conditions. Maintaining consistent moisture is important, but overwatering must be avoided, as lavender cuttings are susceptible to fungal diseases and root rot.
Before making any cuts, all tools, including shears and knives, should be sterilized using rubbing alcohol or a bleach solution to eliminate disease spores. This simple step is a foundational practice in propagation and ensures a healthy start for the new plants. With the right timing, proper preparation, and a focus on well-draining conditions, the new lavender plants should be well-rooted and ready for transplanting within four to six weeks.