How to Prune Lavender — and Why It Matters More Than You Think

Lavender is the most underpruned plant in the UK. People are afraid of cutting into the brown wood, and so they give it a polite trim with the kitchen scissors and hope for the best. Within a couple of years it gets leggy, floppy, and gappy at the base. Within five it looks like it needs replacing. The truth is that lavender responds brilliantly to hard pruning. But only if you do it at the right time and in the right way.

This guide covers when and how to prune lavender plants in the UK, from the annual hard prune in August to the spring tidy-up, deadheading, and renovation of overgrown old plants. If you are looking for advice on planting, soil, or choosing the right variety, see our lavender growing guide.

When to Prune Lavender in the UK

For most British gardens, the annual hard prune happens after flowering in August or early September. This is the single most important thing you do for your lavender all year. Cut too early, and you lose the last of the flowers. Leave it too late, and the new growth will not have time to toughen up (aka "harden off") before winter.

August is ideal. September is fine. October is pushing it. If the new shoots have not hardened off before the first frost, they can be damaged. And never prune in winter when the plant is dormant. The wounds will not heal, and you are inviting rot.

There is also a lighter cut in spring, a deadheading option in summer, and, for the truly brave, a renovation programme for overgrown plants. All of these are covered below.

The 8–8–8 Pruning Rule

This is the simplest way to remember what to do in August. In the eighth month, reduce your lavender hedge to roughly eight inches tall (about 20cm) and eight inches wide. That applies to English lavender and most Dutch Lavandins. French butterfly lavenders are treated more gently. More on that below.

Eight inches sounds dramatic, and when you have just done it, the hedge will look rather sorry for itself. But those little green shoots at the base of each stem — the ones that have been struggling to reach the light all summer — are now exposed. They will put on two or three inches of growth before winter, harden off, and be packed with flower buds for the following year. That is where next summer's display comes from.

The video above shows the technique used on our nursery here in Somerset. You will need hedge trimmers or shears for a hedge, or secateurs for individual plants. A cane or stick with a mark at eight inches makes a useful guide: stick it in the ground at intervals along the hedge, cut a slot at each mark, then join the slots together along the top and down both sides.

The Annual Pruning Calendar

Spring Trim (Late February to Late March)

In late winter, before the main growing season begins, give your plants a light trim. The aim is to remove only the fresh green growth that appeared over winter: the pale, soft shoots at the tips. Think of it as a shave, not a haircut. Do not cut into the older, silvery foliage beneath.

This light trim encourages the plant to send out twice as many new flowering shoots, and it pushes bud growth further down the stem, which keeps the plant compact. On a hedge, you will notice the difference by midsummer. Try it and see. A spring-trimmed row flowers more densely and more evenly.

Summer Deadheading (Late June to July) — Optional

If you cut off the spent flower stalks after the first flush of flowers in late June, you will encourage a stronger second flush in late summer. It is not essential. The seed heads look pleasant enough if you prefer to leave them — but for varieties like Hidcote and Munstead it does make a noticeable difference to the August display.

Hard Prune (August to Early September)

This is the big one. After the last flush of flowers has faded and the colour has gone from the spikes, cut the whole plant back hard to about 20–25cm (8–9 inches) from the ground. The crucial rule is to cut above at least one set of visible leaf buds. They may be tiny, just small green shoots peeking out from the stem — but they should be clearly there. If you cut below the last visible bud, that stem will die.

On a hedge, aim for a roughly square cross-section: flat on top, straight down both sides. The new growth will soften the shape quickly. Within a fortnight the plant will look green again, and by late autumn it will have formed a tight, rounded mound that looks good all winter.

For Grosso and other tall Dutch Lavandins, you can prune a little higher, around 25–30cm, because the plants are naturally bigger. For Phenomenal, the same rule applies but the foliage stays notably silver through winter, which is one of its selling points.

Pruning French and Butterfly Lavender

French lavender (Lavandula stoechas) needs a gentler approach. These are less hardy than English varieties, and cutting hard into old wood carries more risk. After the first flush of flowers fades, usually in early summer, trim back the spent flower heads and shape the foliage into a rounded mound. Do not cut below the green growth into bare brown wood.

In late summer, give it another light trim rather than the drastic 8-inch chop you would give English lavender. If you are growing Papillon or another butterfly lavender in a pot, the late summer trim is also a good time to check the roots and consider whether it needs moving to a larger container.

French lavenders are shorter-lived than English ones. Five years is a reasonable expectation rather than ten — so thorough annual pruning matters even more. A well-pruned Papillon in a sheltered spot can look good for longer than you might expect. An unpruned one will get woody and sparse within three years.

Spring Pruning vs Autumn Pruning — UK vs Europe

If you have read gardening advice from France or southern Europe, you may have come across the recommendation to hard prune lavender in spring. This is standard practice in warmer climates where the growing season is longer and spring arrives earlier. Gardeners in Provence leave the full head of flower stalks on the plant through winter for ornamental interest, then cut hard in March when the sap rises.

In the UK, this does not work as well. Our springs are shorter and colder, so a plant that is hard-pruned in March has less time to recover before it needs to flower. The result is usually fewer flowers and a delayed season. The British method: hard prune in August, light trim in spring — gives the plant the longest possible recovery time before the following summer's display.

	British Method	Southern European Method
Spring (first new leaves)	Light trim — remove new green tips only	Hard prune
Midsummer (after first flush)	Deadhead spent flower stalks	Deadhead spent flower stalks
Late summer (after final flowers)	Hard prune to 20–25cm	Light trim or leave flower stalks for winter interest

Can you hard prune in spring in the UK? Yes, and it will not kill the plant. British gardeners sometimes do it when they have inherited an overgrown plant, when they want to delay flowering on purpose, or when they simply did not get round to pruning the previous autumn. Skipping a year is always worse. But for the regular annual regime, late summer is the better time.

Renovating Overgrown or Leggy Lavender

If your lavender has gone several years without proper pruning and the base is bare, woody, and gappy, the honest answer is that it may be past saving. Lavender does not regenerate reliably from old, leafless wood the way some shrubs do. You can try renovation, but it is not guaranteed.

The best approach is to work in stages over two or three years. In the first autumn, cut back a quarter of the main branches hard, right down to a few inches above the ground — and trim the rest normally. If new growth appears from those hard-pruned branches the following spring, repeat the process the next autumn with the next quarter. Over four seasons you will have renewed the whole plant, one section at a time, without removing all the green growth at once.

Insulating the plant with horticultural fleece during severe cold snaps helps the new buds and soft growth survive that first winter after hard pruning.

If the renovation fails, do not blame yourself. Lavender has a natural lifespan as an attractive garden plant. Roughly a decade for English varieties, rather less for French — and sometimes the kindest thing is to start again with a new plant. It does not suffer from replant disease the way roses do, so you can plant a fresh one in the same spot. Remove the old root ball and swap in some fresh soil from nearby, and the new plant will establish as if nothing was there before.

Common Pruning Mistakes

Cutting too late in autumn. If you prune in October or November, the new growth will be soft and vulnerable to frost. August is ideal, September is fine, October is a gamble.

Not cutting hard enough. A light trim in August achieves very little. The plant needs to be taken down to 20–25cm to expose the low buds. People are afraid of the brown wood, but it is not the wood that matters. It is the leaf buds above where you cut. If you always cut above a visible bud, even a tiny one peeking out of the bark, you should be fine.

Cutting below the last green growth. If there are no visible buds below your cut, that stem will not regrow. Always check before you cut.

Pruning in winter. The plant is dormant and cannot heal the wounds. Wait for late February at the earliest for a light spring trim.

Using blunt tools. Shears or secateurs should be sharp and clean. A ragged cut invites disease. If you are pruning several plants, it is worth wiping the blades between plants with a cloth dipped in diluted disinfectant, especially if one plant looks unhealthy.

Pruning in wet weather. Lavender does not like being cut when it is soaking wet. The combination of open wounds and moisture is an invitation for fungal problems. Pick a dry day.

Frequently Asked Questions

When is the best time to prune lavender in the UK?

After flowering in August or early September. This gives the new growth several months to harden off before winter. A lighter trim in late February or March removes winter damage and encourages denser flowering, but the hard prune after flowering is the one that matters most.

Can I prune lavender in October?

It is better than not pruning at all, but not ideal. The new shoots may not have time to toughen up before frost. If you missed August and September, prune conservatively: take off the spent flowers and shape the plant, but do not cut as hard as you would in August. A thorough trim in the following spring will help compensate.

Should I cut lavender back to the wood?

Not right down to bare brown wood with no visible buds. The old advice was never to cut into the wood at all, but modern practice is bolder: you can cut down to about 20cm (8 inches), as long as you leave at least one set of visible leaf buds on each stem. Those buds are the plant's future. Cut below them and that stem dies.

How do I prune lavender in a pot?

The same way as lavender in the ground: hard prune after flowering in August, light trim in spring. Container lavender can grow faster because the roots are warmer, so it may need slightly more frequent trimming to stay compact. Check the roots at the same time; if the plant has become pot-bound, it is worth moving it into a pot one size larger with fresh compost.

What is the difference between pruning English and French lavender?

English lavender (Lavandula angustifolia) takes hard pruning well and should be cut to 20–25cm in August. French butterfly lavender (Lavandula stoechas) is less hardy and should be pruned more gently: trim spent flowers and shape the mound, but do not cut hard into bare wood. French lavender also benefits from earlier deadheading because it starts flowering a month or more before English varieties.

My lavender is woody and barely flowering — can I save it?

Possibly. Try the quarter-by-quarter renovation method described above, cutting one section hard each autumn over four years. If new green growth appears from the pruned section the following spring, you are in with a chance. If not, the kindest option is a fresh plant. Lavender does not suffer replant disease, so the same spot will work perfectly well for a new one.

August or September is the best time to hard prune Lavender for great flowers the following year

Late August is the absolute best time to prune your Lavender plants, when the final flush of flowers has died down.
September is also fine, but it’s best not to leave it later, or you will get sparser flowers next year.

If you can’t prune your plants in August-September one year, it’s fine to prune Lavender in Spring instead, which is better than pruning in winter. Lavender loves heat, and does not like being disturbed by pruning or transplanting in cold weather!

Read more about growing lavender.

You will need: Hedge trimmer, shears, or secateurs, and a cane or stick with a mark 8 or 9 inches from one end.

Transcript:

It’s that time, the end of August, and the lavender, which has flowered all summer, really, is coming to the end of its flowering season. And this is the time when gardeners have to be brave and take your heart and your secateurs in both hands, and start hacking. Let me show you why.

The reason we’re going to be brave with our secateurs is because, as a negligent gardener, I let my lavender run to seed, and it’s too late to cut it back and get it to flower again. If I’d cut it (deadheaded it) at the end of June, it would be in full flower again now. The reason we cut back hard is that, if I open up this plant and show you, is these little green growths down at the bottom of the plant, which are trying to get to the daylight. So, what we’re going to do is take the top, the sides off the plant now, and I will show you the rule of three eights.

The rule of three eights is in the eighth month, that’s August, which is where we are. We’re going to reduce the height of your lavender hedge to eight inches, and you’re going to reduce its width to eight inches. Marked off, say, on a cane so you can see more clearly what follows.

You see the mark, hopefully clearly, and you put the cane down to soil level, just in a touch, so the mark is roughly eight inches above ground level. I’m going to cut a slot through the top of the edge. I’m doing this with secateurs, normally you would use hedge trimmers, or shears. That’s sort at the eight-inch mark. And then, I move the cane down the hedge a bit and I stick it into the ground as before.

And I’m going to do exactly the same again, and cut the slot. So now I’ve got two slots in the hedge; there’s one. And if I come up the hedge, here’s another one. Join those two together, so the whole of this section will be at eight inches tall. I’m not going to fill the whole thing because it’ll bore you, but I’m keeping my eye on the slot that I’m aiming towards as I cut, so that even though this may not be absolutely precise, I’m going to join them up.

I’ve trimmed my little section. You can see a raggedy bit at one end, a raggedy bit at the other end. In real life, you’re going to have to do this for the whole hedge.

So, the next bit is to take it back down to eight inches wide.

I’ve got my trusty measuring stick, and, this is a bit of judgment, really, hedges grow roughly evenly on either side, so I’m going to kind of trim to the edge of the stick. I’m going to do the same thing: cut a slot at one end, but this time being down. And then I’m going to go to the other end, and I’m going to cut a slot there. And if I’m doing a whole hedge, by the way, these slots, if you use the technique, cut sort of about one every meter, something like that, it’s quite easy to join up.

This is seen from above. I’ve cut a slot here, where my finger is. In there, you can see that the hedge has gone in. I’ve cut one slot there and then I’ve cut another one here, and I’m now going to cut along the edge of the hedge like that on one side, and then on the other side I’m going to do the same thing, join them up. I should have something that’s roughly square in shape, cross-section, eight inches high and eight inches wide.

There’s the raggedy hedge, and you see this nicely clipped little bit, it’s only about thirty centimetres long, just for the video, and then it goes raggedy again.

So you can see that the top’s been taken off, and that the sides’ve been taken off on both sides.

The reason that we do this, as explained at the outset, is when you cut down the side of the hedge like that down here, these little growths, you can see little green growths, there’s one there.

Those suddenly see the light. This year, they’re going to put an appreciable amount of growth. You can easily see, oh, two or three inches. They’re going to harden off. As winter comes, if there’s a frost, they’ll get through the frost, and they’re going to be full of flower buds in a nice tight, tight bush for next spring.