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Lavender has almost no dormant buds in its old wood. Cut a stem back into the bare brown part below the leaves and it will not reshoot; it simply dies back to the point where it joins live wood, and a gap opens in the plant that never closes. This is the single most common way gardeners destroy a healthy lavender, usually with the best intentions after letting it get too big.
So before every cut, look for green. Run your hand into the plant and find where the lowest small leaves are on the stem you are about to cut. Leave at least an inch (2 to 3 cm) of leafy growth, with a few pairs of leaves, below your cut. If you cannot see leaves at that height, you cannot cut there.
There is no rescue for a stem cut into bare wood. If a whole plant has been cut back hard by mistake, leave it alone for a full season rather than cutting further; occasionally a few buds break, and cutting again removes the last chance.
Cut twice a year, and neither cut is drastic
A lavender kept in shape gets two cuts. The first is right after flowering, taking off the spent stalks and an inch or so of the leafy growth beneath them. The second is a firmer shaping cut in late summer or very early autumn, taking the plant back into a tight dome while there is still enough warm weather for the cut surfaces to callus and for a little new growth to harden off.
Timing that second cut matters. Cut too late, into cold weather, and the soft regrowth is caught by frost and the whole plant goes into winter damaged. Allow at least six weeks of growing weather between the shaping cut and your first expected frost.
| Cut | When | How much | Purpose |
|---|---|---|---|
| Deadheading | As soon as flowers fade | Flower stalks plus an inch (2 to 3 cm) of leaf | Tidies the plant and can trigger a second flush on English types |
| Shaping cut | Late summer, six weeks before first frost | Back to a dome, about a third off, always into green | Keeps the plant dense and stops the base going bare |
| Spring tidy | Once new growth starts | Frost-damaged tips only | Removes winter damage without cutting live wood |
| Hard renovation | Not recommended | None | Old wood does not reshoot; replace the plant instead |
Shape it as a dome, not a flat top
Cut lavender into a rounded mound with the sides sloping outward at the base. A dome sheds rain and snow, catches light on every part of the surface, and keeps the outer growth leafy right down to the ground. A flat-topped or straight-sided plant shades its own lower growth, and that shaded growth drops its leaves and turns into the bare wood you can never cut into later.
Work with hand shears rather than a hedge trimmer on individual plants, and stand back every few cuts to check the outline. On a lavender hedge a trimmer is fine, but set the depth by testing one plant with shears first so you know where the green stops.
- Find the green line first Before you start, part the foliage on two or three stems and note how far down the leaves go. That depth is your limit for the whole plant. On an old plant it may be only two inches (5 cm) of leafy growth, and the shaping cut has to be correspondingly light.
- Take the flower stalks off first Removing the spent stalks lets you see the actual shape of the leafy mound underneath. Trying to judge the outline through a forest of flower stems leads to cuts that are far deeper than intended.
- Cut the sides before the top Establish the width first, sloping outward towards the base, then round the top over to meet it. Doing it the other way round almost always leaves the plant flat-topped and too wide.
- Leave the base wider than the top A base wider than the crown keeps light on the lower foliage, which is the growth you will need to cut into next year.
Pruning differs by type
English lavender takes the firmest cut of the three groups and reliably breaks from the leafy growth, so the late summer dome cut can take about a third of the plant. Lavandins are bigger and grow away strongly, but they also carry a taller skirt of bare wood, so measure the green carefully and expect to take proportionally less.
The French and Spanish group is different again. They flower on new growth in flushes through the season, so they want light, frequent trimming: take off spent heads with a couple of inches (5 cm) of stem whenever a flush finishes, and give them one gentle shaping in early autumn. Never give this group the same firm cut as English lavender, because they are less able to break from older growth and are more likely to be sitting on frost-damaged wood.
What to do with an old, split, woody plant
A lavender that has been left unpruned for years ends up as a splayed ring of gray wood with a hole in the middle and a fringe of green at the tips. There is no cut that fixes this, because everything you would need to remove is bare. Do not attempt renovation.
Instead, take cuttings from the healthy tips in summer, grow them on, and plant the replacements in a properly prepared position. Keep the old plant flowering for a year or two while the young ones establish, then remove it. Lavender is short-lived by nature; even a well-pruned plant is usually best replaced somewhere between eight and fifteen years.
Note the date of each pruning cut and how much you took off. After two seasons the record tells you whether your late summer cut is timed early enough for the plant to harden off, which is the detail most people guess at year after year.