At a glance
Pruning is the single most important maintenance task for lavender. Without it, plants become woody, open in the centre, and stop flowering well within three to four years. The woody base that forms when lavender is left unpruned cannot produce new growth, and a plant that has gone fully woody will not recover regardless of how well it is subsequently cared for. Regular pruning keeps the plant compact and bushy, encourages new growth from which the following year’s flowers will develop, and extends the productive life of the plant significantly.
A well-pruned lavender can remain productive for ten years or more. One that has never been pruned is often beyond saving by year five. The technique is not difficult, but understanding why the golden rule of never cutting into old wood exists is what prevents the most common mistake.
What pruning does for lavender
Lavender is a woody shrub that produces its flowers on new growth. The soft leafy shoots that emerge each spring carry the following summer’s flower buds. If the plant is not cut back after flowering, the growth from the previous year remains as old, increasingly woody stem. Each year that passes without pruning adds another layer to this woody base, and the proportion of the plant capable of producing flowering shoots shrinks. The pruning cut removes the spent flowering growth and enough of the leafy material beneath it to stimulate a flush of new shoots, which become the source of next year’s flowers. It also maintains the compact, rounded shape that keeps lavender looking good and allows air to circulate through the plant.
The two main pruning times
Lavender is pruned twice a year for best results: once after flowering in late summer, and optionally again lightly in spring. These two cuts have different purposes and should not be confused with each other.
How to do the late summer prune
The key rule is never to cut back into old wood. Lavender does not regenerate from brown, leafless, woody stems. The cut must always leave green foliage below it. If in doubt, cut less: it is better to leave the plant slightly larger than intended than to cut into wood with no leaves.
Species and variety differences
The species of lavender determines how hard it can be pruned, how hardy it is, and whether the late summer cut is appropriate. The table below covers the three groups most commonly grown in UK gardens.
Within English lavender and lavandin, compact varieties such as Hidcote and Munstead need less material removed than larger spreading types such as Vera or Grosso. The rule remains the same but the finished size will differ.
First year plants
Newly planted lavender should not be pruned hard in its first year. The plant needs to establish a good root system and should be allowed to grow freely through its first summer. Deadheading the flowers after they fade is acceptable, but no significant pruning should be done until the plant is in its second season. Removing any dead or damaged stems is fine, but leave the main structure completely untouched in year one.
What happens if lavender is not pruned
A lavender that is never pruned will gradually become leggy and open-centred, with long bare woody stems at the base and flowering growth confined to the tips. In the first year without pruning the plant may still look acceptable. By the second and third year, the woody base becomes increasingly prominent and flowering coverage reduces. By year four or five, the plant often splits open in the centre, the woody stems become brittle, and flowering becomes sparse. At this stage, renovation is very difficult and replacement is usually the better option. The woody base cannot be reversed. Prevention through annual pruning is the only reliable strategy.
Never cut into old brown wood. Unlike many shrubs, lavender does not regenerate from bare woody stems. Once a stem has lost its leaves and turned brown and woody, cutting it will leave a dead stump. Always ensure there is green foliage below the cut before pruning any part of the plant.
Renovating a neglected lavender
If a lavender has been left unpruned for several years but has not yet gone completely woody, there is a chance of recovery through careful renovation over two seasons. The approach is to cut back hard into the green foliage in early spring over two consecutive years, cutting further back each time while always ensuring green leaves remain below the cut. Do not attempt to restore the plant in one year by cutting all the way back at once.
The honest assessment is that most lavenders that have developed a significant woody base will not recover fully. Renovation is worth trying on plants of sentimental value or unusual varieties, but for standard plants, replacement with a new young plant is usually the more reliable route to a productive garden lavender.
Watering
Established lavender in the ground needs very little watering. It is a plant of dry Mediterranean hillsides and is adapted to drought. Overwatering is a more common problem than underwatering and is one of the main causes of root rot and plant death. The table below covers when watering is needed and when it should be avoided.
Feeding
Lavender does not need or benefit from rich feeding. Heavy nitrogen feeding produces lush soft growth with poor flowering and increases susceptibility to fungal disease. In poor, free-draining soils, a light application of a low-nitrogen fertiliser such as a tomato feed or slow-release balanced granules in spring is sufficient. In good garden soil, no feeding is needed at all. Soil improvement before planting is more useful than ongoing feeding throughout the life of the plant.
Soil and site
Lavender requires full sun and excellent drainage. It will not thrive in shade or in soils that hold water. Heavy clay is the most common cause of lavender failure in UK gardens. If the garden soil is clay, plant in raised beds, large containers, or beds improved with significant quantities of grit and sharp sand. The table below shows the site and soil conditions and how well lavender tolerates each.
Pests
Lavender has few serious pest problems. The three worth knowing about each have a distinct appearance that makes identification straightforward.
Diseases
Three diseases are worth knowing. Two are fungal conditions that affect the above-ground growth, and one is a root disease caused by poor drainage.
Common problems
Most problems with lavender trace back to one of a small number of causes. The flowchart below helps identify what is wrong and what to do.
Propagation
Lavender is easily propagated from cuttings taken in late summer, immediately after the pruning cut. The trimmed material from the main prune makes an ideal source of material. Select shoot tips around 8 to 10 centimetres long that have no flowers on them, strip the lower leaves leaving a short length of bare stem, and insert into gritty compost or equal parts compost and sharp sand, around three to four cuttings per pot. Water in and place in a cold frame or unheated greenhouse for the winter. Roots develop over winter and the cuttings will be ready to pot on by the following spring. Softwood cuttings can also be taken in spring from new growth and root faster, but need protection from drying out. Lavender does not divide easily and cuttings are the standard propagation method.
Long-term management
Even with annual pruning, lavender plants eventually reach a point where the woody base becomes too large and the plant starts to decline in vigour. For most varieties this comes somewhere between eight and twelve years. Planning for replacement before the plant declines is sensible: taking cuttings from a healthy plant to produce replacements means there is never a gap in the planting when the time comes to remove the original. Lavender planted in a hot, sunny, south or south-west facing position with excellent drainage will outlast one planted in a marginal spot by many years. The investment in site improvement before planting is repaid many times over in plant longevity.
Companion planting and position
Lavender combines well with other Mediterranean-climate plants that share its preference for free-draining soil and full sun. Rosemary, sage, cistus and catmint are natural companions in beds designed around these conditions. Ornamental grasses provide textural contrast and tolerate similar drainage. Roses work well beside lavender in formal schemes: the lavender benefits from the same conditions and its flowers attract pollinators and provide competition for aphids that might otherwise concentrate on the roses.
Toxicity
Mildly toxic to pets. Lavender essential oil in concentrated form can be harmful if ingested, and the plant itself is mildly toxic to dogs, cats and rabbits, potentially causing nausea and digestive upset if eaten in significant quantities. Keep pets away from the plant if they are known to chew garden plants.
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