Late summer is the time to prune. Learn why it matters, when to cut (six weeks before frost), and how the top-third rule keeps your lavender mounded, healthy, and blooming for years.
Some people never prune their lavender because they're too nervous to cut enough or overcut. Both end up with a woody plant with a few sad green tips, shortening its lifespan.
Pruning is the one bit of maintenance lavender genuinely needs, and September is when it often happens. Here's how to do it without hurting the plant.
Why You Need to Prune Your Lavender
Lavender is technically a shrub, and shrubs build wood. Every year the plant lays down another layer of hard grey stem at the base and pushes its green growth further out toward the tips. If you skip pruning for a few seasons, you get a hollow center with foliage flopping outward.
Trimming annually keeps the plant tight and mounded, opens up airflow through the middle (which matters a lot in Missouri humidity), helps it shed snow instead of splitting under the weight, and gives you more flowers next summer. A well-pruned plant will give you 10 to 15 good years. An unpruned one is usually finished by year five.
When to Prune: Six Weeks Before Frost
Cutting a plant back tells it to grow, and tender new growth going into a freeze is exactly what you don't want. Six weeks gives that growth time to harden off first.
Around here, first frost usually lands mid-October, which puts our pruning window in early to mid-September. Count back from your own frost date if you're somewhere colder or warmer.
Pro Note: If you miss the window, leave the plant alone and wait until spring. A shaggy lavender that survives winter beats a freshly cut one that doesn't.
How to Know Where to Cut Your Lavender Plant
Before you make a single cut, get down at eye level with the plant and look at where the wood ends.
You'll see two distinct zones:
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The woody base. Grey or brown, hard, and leafless. This part of the plant won’t produce new growth.
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The soft green growth. Soft, silvery, leafy. Every future shoot and flower comes from here.
Lavender doesn't reliably resprout from old wood, so if you cut into the bare grey, you'll usually be left with a stub that never leafs out again.
Every stem you cut should still have green leaves on it when you're done.
How to Prune Lavender: The Top-Third Rule
Wait for a dry day and use sharp bypass pruners, not anvil pruners, which crush the stems.
Gather the foliage loosely in one hand like a ponytail and cut off about a third of the plant's height. That's the spent flower stalks plus a good portion of the green underneath. Deadheading alone isn't pruning; you have to come down into the foliage.
Work around the plant and shape as you go, rounding it into a dome that's higher in the center and slopes evenly to the edges. Then step back a few feet and check the silhouette. Flat spots are much easier to see from a distance than from directly above.
Not All Lavender Takes the Same Cut
This is where people get into trouble, so check which plants you have.
English lavender (Lavandula angustifolia) is forgiving. You can take a full third or a little more, coming down fairly close to the woody base, as long as an inch or two of green stays on every stem. It branches readily and fills back in.
Lavandin (Lavandula x intermedia) is bigger, blooms later, and is much less forgiving. These hybrids die back when cut hard and are slow to recover. Take the top third and stop there, leaving a generous cushion of green above the wood.
Not sure which you have? Lavandins are larger plants with longer stems and a sharper, camphor-like scent. Angustifolias are tidier, bloom earlier, and smell sweeter. We harvest them for culinary lavender.
When in doubt with a lavandin, cut less.
What About a Plant That's Already Gone Woody?
Don't try to fix it in one season. A hard renovation cut into old wood usually kills the plant outright.
Instead, prune a little lower each year, always staying just above the green, and let it rebuild density gradually. Two or three seasons of this can bring back a decent shape. If a plant has truly split down the middle and gone hollow, it's often kinder to replace it and start good habits from year one.
Don't Waste the Clippings
Everything you just cut off your lavender plant is still fragrant. Strip the buds for sachets and drawer bundles, braid the longer green stems into wands, or toss a handful on the coals at your next fire. The woodier bits make excellent fire starters.
A word of warning, though: September clippings are past their peak. The oils are strongest right at bloom, so what you gather now will be gentler and won't hold its scent as long as a June harvest would. If you're planning holiday gifts, you can shop our products here.
Give your plants their haircut this month, and they'll be worth walking through come June.
Happy pruning!
