Lavender

Lavender is one of the most recognizable garden plants, but also one of the most incorrectly pruned. Anyone who cuts too deep and reaches the bare, woody part will get no new growth. This plant profile explains why this happens, when you can prune, and how to keep lavender compact.

Why lavender doesn’t regrow from bare wood

Lavender becomes woody from the base upwards, and that old, bare wood no longer produces new shoots. If you prune back into that brown, leafless part, the branch remains dead. This behaviour is characteristic of many subshrubs and stands in stark contrast to, for example, yew, which as one of the few conifers does sprout from old wood. This precise difference means that a general pruning rule for ‘shrubs’ does not exist.

When pruning lavender, you therefore leave a few centimetres of green foliage on each branch. Prune to just above the first new shoots that appear in March at the base of the previous year’s growth, but go no further. Anyone who forgets this for several years in succession and cuts progressively deeper will see the plant become bare from the inside out. You cannot remedy this by waiting, the plant simply does not make that choice.

In practice, this means that in March you reduce the plant by about a third, to just above where you see the first green leaves. This keeps lavender compact. If you neglect this, the plant will fall open over the years and you’ll get a bare ring in the middle with flowers only at the tips. This picture is often seen in gardens where lavender has stood for years but has never been pruned.

The two pruning times

You prune lavender twice a year. At the end of March or beginning of April you cut the plant back to just above the first new green shoots. This timing keeps the plant compact and prevents it from falling open. In August, after flowering, you cut off the spent flower spikes with a light shaping prune. This second timing prevents the plant from setting seed and putting energy into something other than new foliage.

The spring pruning is the most important. Anyone who skips this loses the compact form and gets long, floppy stems that lie flat on the ground after rain. The August pruning is less drastic but still useful, it removes the spent material and gives the plant a few more weeks to produce some new green growth before winter.

Don’t prune too late in autumn. Anyone who still prunes in October triggers new shoots that won’t survive the first frost. This weakens the plant. August is the last safe month for a light correction. After that you leave lavender alone until spring.

Position: drought is no problem, wet feet are

Lavender comes from the Mediterranean region and tolerates drought effortlessly. What kills it is a wet winter in heavy soil. A lavender plant standing in a puddle in November won’t make it to February. Drainage is more important than frost protection.

Plant lavender higher if you have heavy clay, or work grit or sharp sand into the soil. That helps more than covering. Lavender survives Dutch winters without problems if the water can drain away. Don’t add compost or rich soil, that retains moisture and that’s precisely what you don’t want.

Full sun is essential. In partial shade lavender remains floppy, flowers less and is more susceptible to fungal disease. Plant it in the warmest, driest spot in the garden, where other plants would struggle. That is ideal for lavender.

Which lavender is hardy

There are two types of lavender you’ll encounter in garden centres, and only one of them is reliably hardy in the Netherlands. Lavandula angustifolia, English lavender, survives without problems. Lavandula stoechas, French lavender with the distinctive bracts on top of the flower spike, does not do so reliably.

Much disappointment about ‘lavender that didn’t make it’ stems from this. French lavender looks spectacular, flowers early and therefore sits prominently on the shelf, but it comes from warmer regions and freezes to death here. When purchasing, pay attention to the botanical name, not the colour of the label or the size of the flower.

Within Lavandula angustifolia there are cultivars that remain slightly more compact or flower slightly darker, but the pruning behaviour and hardiness are the same. ‘Hidcote’ and ‘Munstead’ are well-known selections, but even an unnamed L. angustifolia from the market does fine if the position is right.

Lavender for bees and butterflies

Lavender is one of the richest nectar sources in the summer garden. From June to August bumblebees, honeybees and butterflies are in the flowers, often so busy that the plant hums. This makes lavender valuable at a time when many other plants have already finished flowering or haven’t yet got going.

The August pruning should therefore only happen after flowering. Anyone who prunes too early removes food at the moment insects need it. Leave some of the spent flower spikes until spring if you want to help insects, the plant doesn’t suffer from this and seed provides winter food for birds.

Plant lavender in groups, not as a solitary specimen. Three or five plants together attract more insects than a single plant. Combine lavender with other summer flowers such as sage or catmint for a long flowering period, that keeps the supply for pollinators going.

Every garden differs in soil type, light and microclimate, and cultivars within a species can have slightly different requirements. For questions about toxicity to children or pets, always check with the National Poisons Information Centre or a vet, and don’t rely solely on an article.