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The best time to cut back lavender in Colorado is in early spring, right when you start seeing new green growth at the base of the plant.
Knowing when to cut back lavender in Colorado matters because our climate throws curveballs that gardeners in milder zones don’t deal with.
If you cut back lavender in Colorado at the wrong time, you can lose the plant to winter kill or stunt its blooming for the entire season.
In this post, we’ll walk through exactly when to cut back lavender in Colorado, how much to trim, and the mistakes that trip up even experienced gardeners here.
Let’s dig in.
When to Cut Back Lavender in Colorado
When to cut back lavender in Colorado comes down to two windows: early spring and right after bloom.
Here’s how to time each one.
1. Early Spring (March to Early April)
The best time to cut back lavender in Colorado is early spring, once the worst of the cold has passed but before the plant pushes out too much new growth.
Along the Front Range, that’s usually March into early April.
In the mountains or higher elevations, wait until late April or even May.
You want to see tiny green shoots emerging from the woody base before you make a single cut.
Cutting back lavender in Colorado before those signs show up risks exposing the plant to a late freeze that can kill it outright.
2. After the First Bloom (Late June to July)
A second window to cut back lavender in Colorado opens right after the first flush of flowers fades.
Deadheading and lightly shaping the plant at this point encourages a second bloom and keeps it tidy.
This is a lighter trim than the spring cut, just enough to remove spent flower spikes and a bit of soft growth.
3. Why Fall Pruning Is a Bad Idea in Colorado
Cutting back lavender in Colorado in fall is one of the most common mistakes.
Pruning stimulates new growth, and new growth won’t harden off before our first hard freeze.
That tender growth dies back, and the dieback can spread into the woody stems, killing the whole plant over winter.
If you must tidy things up in fall, stick to snipping off spent flower stalks only and leave the foliage alone.
How Much to Cut Back Lavender in Colorado
How much you cut back lavender in Colorado depends on the age and health of the plant.
Here’s the rule of thumb.
1. Never Cut Into the Woody Base
Lavender doesn’t reliably regrow from old wood, so cutting back lavender in Colorado means staying in the green.
Leave at least two or three inches of green growth above the woody stems.
If you cut into bare wood, that stem usually won’t sprout again.
2. Trim About One-Third of the Plant
A good spring cut removes roughly one-third of the overall foliage.
Shape the plant into a rounded mound rather than a flat-top haircut, which exposes the center to sunscald.
This keeps the plant compact and encourages bushier growth through summer.
3. Start Young Plants Gently
First-year lavender barely needs pruning.
Just pinch off the tips to encourage branching.
By year two or three, you can cut back lavender in Colorado more aggressively, following the one-third rule.
Colorado-Specific Tips for Pruning Lavender
Colorado’s swings between warm days and freezing nights make timing everything.
Here’s what else to keep in mind.
1. Watch Your Elevation
When to cut back lavender in Colorado shifts with elevation.
Denver and the plains warm up earlier, so March works.
Higher up in Evergreen, Aspen, or Durango, push your pruning back a few weeks to be safe.
2. Prune on a Dry, Mild Day
Cut back lavender in Colorado on a dry day when no freeze is in the forecast for at least a week.
Fresh cuts need time to callous over, and wet conditions invite disease.
3. Skip the Fertilizer
Lavender thrives in lean, rocky soil, which is why it does so well here.
Don’t fertilize after you cut back lavender in Colorado, since rich soil makes plants floppy and short-lived.
4. Clean Your Shears
Always sanitize your pruners before you cut back lavender in Colorado.
A quick wipe with rubbing alcohol prevents spreading disease between plants.
So, When Should You Cut Back Lavender in Colorado?
You should cut back lavender in Colorado in early spring, once you spot new green growth at the base, and again lightly after the first bloom fades.
Avoid cutting back lavender in Colorado in fall, since new growth won’t survive our freezes.
Stick to the one-third rule, never cut into old wood, and time your trim around your elevation.
Do that, and your lavender will reward you with healthy growth and plenty of blooms year after year.