Understanding Lavender Plant Division
The question of whether you can divide lavender plants is a common one among gardeners looking to propagate their beloved herbs or manage larger specimens. Fortunately, the answer is a resounding yes, though it's not always the primary or most straightforward method for all lavender varieties. Dividing a mature lavender plant involves carefully separating a clump into smaller sections, each possessing its own root system and stems, which can then be replanted to form new, independent plants.
While propagation through cuttings is often favoured for its success rate and ease with many lavender types, division offers an excellent alternative, particularly for woody, established plants that may have become leggy or too large for their space. It's a practical way to rejuvenate older plants, increase your stock of a particular favourite like Hidcote lavender plants, or simply share your bounty with fellow garden enthusiasts. This technique is best suited to younger, vigorous plants or clumps that have started to thin in the centre, indicating a need for rejuvenation.
When is the Best Time to Divide Lavender?
Timing is crucial when considering when to prune lavender or when to divide lavender plants. The ideal window for division is typically in the early spring, as new growth begins to emerge, or in early autumn, after the main flowering period has passed but before the first hard frosts arrive. Spring division allows the plant ample time to establish its roots in warmer soil before the heat of summer, minimising transplant shock. Autumn division gives roots a chance to settle in before winter dormancy, though care must be taken to ensure adequate establishment before temperatures plummet.
Avoid dividing plants during the peak of summer when heat stress can severely impact newly divided sections. Similarly, dividing during winter dormancy is generally not recommended, as the plant is less resilient and root recovery will be slow. Preparing the soil and the divided sections beforehand can significantly improve the success rate of this propagation method.
Assessing Your Lavender Plant for Division
Before you start, it is important to assess the lavender plant itself. Look for signs that indicate it's a good candidate for division. Overgrown plants that are spreading widely, becoming woody at the base, or developing bare patches in the centre are prime candidates. Younger plants, typically 2-3 years old, are often easier to divide successfully than very old, woody specimens, which may have a dense, tough root ball that is difficult to separate without causing damage. You are essentially looking for a plant that has formed a substantial clump and has multiple growing points radiating from a central mass.
Dividing overgrown lavender is a practical way to restore vigour and expand your collection, offering a more immediate result than starting from seed or cuttings for some varieties.
The core principle of successful division relies on ensuring each new section has a healthy portion of roots and at least one or two viable shoots.
Prepare new planting locations in advance with well-draining soil amended with grit or sand. Water the parent plant thoroughly the day before dividing to help loosen the soil and reduce stress on the roots.
The Process: How to Divide Lavender Plants
Wondering how do you take cuttings from lavender plants versus dividing them? While cuttings involve taking stem sections, division is about splitting a root ball. The process requires a sharp, clean tool and a gentle, methodical approach.
Steps for Dividing Your Lavender
To begin, carefully dig up the entire lavender plant using a spade, ensuring you go wide enough to capture the majority of the root system. Gently shake off excess soil to get a clear view of the roots. If the plant is very large or has a dense root ball, you might need to use two garden forks, prongs facing each other, to prise the root ball apart, or a sharp, clean spade or knife to cut through thicker roots and rhizomes. The goal is to create sections that are manageable and contain a good balance of root and foliage.
Each section should ideally have a minimum of 3-5 healthy shoots and a substantial root system. Inspect each division for any damaged or diseased roots and prune them away cleanly. Once divided, immediately replant the new sections into their prepared spots, spacing them appropriately to allow for future growth. Water them thoroughly after planting. You might consider temporarily shading the newly divided plants for a few days if conditions are particularly hot or sunny to help them acclimatise.
Alternative Propagation: Lavender Cuttings
For many gardeners, taking lavender cuttings is a more popular and often more successful propagation method than division, especially for cultivars that don't divide as readily or for those seeking to propagate young, softwood growth. Cuttings are typically taken in late spring or early summer from non-flowering shoots, treated with rooting hormone, and planted in a free-draining compost mix. This method requires a bit more patience but can yield a high success rate for many varieties.
The key difference lies in the starting material: division works with existing root structures, while cuttings establish new roots from stem sections.
While division is a direct way to multiply plants, cuttings offer a method to start plants from scratch from a parent specimen. It’s worth noting that not all lavender varieties respond equally well to division. Some, like certain English lavenders (Lavandula angustifolia), tend to divide more easily than others, such as the more woody French lavender (Lavandula stoechas). If division proves difficult, consider taking cuttings instead.
Aftercare and Success Factors
Once you have successfully divided your lavender plants, providing the right aftercare is critical for their survival and establishment. Newly divided plants are more susceptible to stress, so consistent, appropriate care will significantly improve their chances of thriving.
Watering and Feeding
Water the divided plants regularly, especially during their first few weeks, until they show signs of new growth. Ensure the soil drains well; lavender detests 'wet feet', and overwatering can lead to root rot, a common problem for stressed plants. Aim to keep the soil consistently moist but not waterlogged. As the plants become more established, you can gradually reduce the frequency of watering, allowing the soil to dry out slightly between waterings, which is closer to lavender's natural preference.
Regarding feeding, lavender is not a heavy feeder. In fact, too much fertiliser can lead to lush foliage at the expense of flower production and can make the plant more prone to disease. For divided plants, a light feeding with a balanced, low-nitrogen fertiliser after a few weeks, or mixing a small amount of slow-release fertiliser into the soil at planting time, is usually sufficient. Avoid strong fertilisers, especially for plants that are already showing signs of stress.
Protecting New Divisions
For plants divided in early spring, be vigilant for late frosts. While lavender is generally hardy, young divisions may be more vulnerable. Providing a layer of mulch around the base (but not touching the stems) can help retain soil moisture and regulate soil temperature, offering some protection. Ensure good air circulation around the plants, as this is vital for preventing fungal diseases, especially in damp conditions.
Monitoring for pests and diseases is an ongoing task, but particularly important for newly divided plants which are in a vulnerable state.
If you are growing lavender indoors, ensure the indoor lavender plant receives plenty of bright light and good air circulation. Dividing indoor lavender may require slightly different timing, often best done when repotting in spring, and ensuring the new pots have excellent drainage.
If your divided plants appear to be struggling or show signs of wilting, check the soil moisture. Often, the problem is either too much or too little water, or poor drainage leading to root issues.
When to Prune Lavender for Best Results
While division is a propagation technique, understanding when to prune lavender or when to cut lavender back is crucial for the overall health, shape, and flowering of your plants, whether they are divided or not.
The Two-Prune Approach
Most lavender varieties benefit from a two-stage pruning regime. The first prune typically occurs right after the main flowering period has finished, usually in late summer. This involves cutting back the spent flower stalks, which encourages the plant to produce a second, smaller flush of flowers in some varieties and prevents the plant from setting seed, thereby directing energy into vegetative growth. This cut should be made just above a set of leaves, removing the flowering stems but being careful not to cut into the old, woody growth.
The second, more significant prune, often referred to as the 'main prune', is best carried out in early spring. This is when you shape the plant and remove any dead, damaged, or leggy growth that occurred over winter. The aim is to maintain a compact, bushy shape and encourage new, healthy stems from which future flowers will emerge. It's crucial to prune before the plant starts its vigorous spring growth. Avoid pruning in late autumn, as this can leave the plant vulnerable to frost damage over winter.
Pruning Specific Lavender Types
Different types of lavender have slightly different pruning needs. English lavenders (Lavandula angustifolia), such as Hidcote lavender plants, are generally hardier and respond well to a firm spring prune. French lavenders (Lavandula stoechas) tend to flower for longer and benefit from deadheading spent flowers throughout the summer to encourage more blooms. Spanish lavenders (Lavandula stoechas) can be pruned lightly after their main flowering flush.
The overall goal of pruning is to maintain a healthy, balanced plant that promotes abundant flowering and prevents it from becoming overly woody and straggly.
When pruning a lavender plant, always use clean, sharp secateurs or shears. This ensures a clean cut, which heals faster and reduces the risk of disease. For very old, woody plants that have become sparse, a more drastic prune might be necessary, but this should be done with caution, as lavender can be slow to recover from severe cutting into old wood.