If you’re wondering when to prune butterfly bushes, late winter or early spring is usually the sweet spot. Butterfly bushes bloom on the new growth they put out each year, so cutting back the old stems before spring growth really gets going gives them plenty of time to fill back out and produce those long summer blooms.
Here at Bobby & Lynn’s Plant Farm in Georgia, we usually start thinking about butterfly bush pruning in late February into early March. Your timing may be a little earlier or later depending on where you live and what kind of winter you are having.
Quick Answer: When to Prune Butterfly Bushes
The best time to prune butterfly bushes is in late winter or early spring, after the worst of the cold weather has passed but before the plant puts on a lot of new growth.
Established butterfly bushes can often be cut back fairly hard. For many full-size varieties, leaving roughly 12 to 24 inches of healthy growth above the ground works well.
Gardeners in colder climates should wait longer than gardeners in warmer areas. If winter regularly kills the stems back to the ground where you live, wait until spring growth begins to show you what survived.
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Why Butterfly Bushes Benefit From Pruning
Butterfly bushes can grow fast. A healthy plant may put on several feet of growth during a single season.
That is great when you want flowers, but after a few years the shrub can become tall, woody, crowded, or awkwardly shaped.
Pruning can help:
- Remove dead and winter-damaged stems
- Encourage fresh new growth
- Keep the shrub at a manageable size
- Improve the overall shape
- Open up crowded growth
- Encourage larger flowering stems
Butterfly bushes are particularly forgiving because most common Buddleia davidii types flower on new growth.
When to Prune Butterfly Bushes in Warmer Climates
Gardeners in the South can usually prune earlier than gardeners farther north.
Here in north Georgia, late February through early March is often a good window.
I still would not prune just because a certain date appears on the calendar.
Take a look at the weather.
If several nights of unusually hard freezing weather are still expected, there is usually no reason to rush. Waiting another week or two will not hurt anything.
Once the worst winter weather appears to be behind us and the plant is beginning to wake up, it is time to get the pruners out.
When to Prune Butterfly Bushes in Colder Climates
In colder regions, butterfly bushes may behave almost like perennials.
The top growth can die during winter while the roots and crown remain alive underground.
If yours looks completely dead in February, do not immediately assume the entire plant is gone.
Give it some time.
NC State notes that Buddleja davidii may die back to the ground in Zones 5 and 6 and then produce vigorous new growth in spring.
Once new growth begins appearing near the base, you will have a much better idea of which old stems can be removed.
How Far Back Should You Prune a Butterfly Bush?
For many established, full-size butterfly bushes, you can cut the stems back to approximately 12 to 24 inches above the ground.
You do not have to measure every stem.
The main idea is to remove much of the old, woody growth while leaving a healthy framework from which the shrub can regrow.
Some mature butterfly bushes can be cut even lower.
NC State recommends pruning certain Buddleja davidii cultivars to about one foot from the ground to maintain their shape and encourage larger flowers.
However, not every butterfly bush needs the same treatment.
Dwarf and compact varieties may need considerably less pruning than an old full-size butterfly bush that has grown six or eight feet tall.
Always consider the mature size and growth habit of the particular variety you have.
How to Prune Butterfly Bushes Step by Step
Start by standing back and taking a good look at the entire shrub.
You do not need to start cutting the second you walk up to it.
First, look for dead, damaged, weak, or crossing stems.
Remove Dead Wood
Start with obviously dead stems.
If you are unsure whether a stem is alive, lightly scratch a small area of bark.
Green tissue underneath usually means the stem is alive.
Brown, dry tissue generally means that portion is dead.
Work your way farther down the stem until you find healthy tissue. If the entire branch is dead, remove it near the base.
Remove Weak or Crowded Growth
Next, remove thin or weak stems and any branches growing awkwardly through the center of the shrub.
Opening the center slightly can improve airflow and gives the new shoots room to grow.
Cut Back the Remaining Stems
Now shorten the healthy stems.
For an established full-size butterfly bush, that may mean cutting the plant back to somewhere around 12 to 24 inches.
Make clean cuts rather than leaving torn or crushed stems.
When you finish, the butterfly bush may look surprisingly small.
That is okay.
Once warm weather arrives, a healthy butterfly bush can grow remarkably fast.
Don’t Be Afraid of a Hard Pruning
This is one of the questions we hear quite a bit.
People look at a big butterfly bush and are afraid that cutting it back severely will kill it.
With an established plant, the opposite is often true.
Because butterfly bushes flower on new wood, a strong late-winter or early-spring pruning can encourage vigorous fresh growth.
Some cultivars can even be pruned close to the ground.
For example, NC State reports that its compact Lo & Behold ‘Blue Chip’ butterfly bush can be pruned to the ground in late winter where the above-ground stems survive winter, encouraging stronger growth, better shape, and more flowers.
What We See After Pruning Butterfly Bushes at Our Plant Farm
Here in north Georgia, a freshly pruned butterfly bush can look pretty rough at first. After a hard late-winter pruning, there may not be much left but a short framework of woody stems.
Once the weather warms, that changes quickly. New shoots begin pushing from the remaining stems and around the base, and the plant starts filling back out.
That is why we don’t judge a butterfly bush by how it looks the day we prune it. The goal isn’t to make it pretty in February. The goal is to encourage healthy new growth that can carry plenty of flowers through summer.
What Tools Do You Need to Prune Butterfly Bushes?
You really do not need a pile of tools.
For most butterfly bushes, two will handle nearly everything.
Hand Pruners
Hand pruners are best for smaller stems.
We prefer bypass pruners because the two blades pass one another and make a clean cut rather than crushing the stem.
We use Corona pruning tools around our plant farm and they are what we tend to reach for when we have a lot of pruning to do.
You can find the pruning tools and other garden supplies we recommend.
Hand pruners are best for smaller stems.
We prefer bypass pruners because the two blades pass one another and make a clean cut rather than crushing the stem.
We use Corona pruning tools around our plant farm, and they’re what we tend to reach for when we have a lot of pruning to do. These Corona bypass pruners are a good example of the type we use for smaller butterfly bush stems.
Loppers
Once a butterfly bush develops thick woody stems, hand pruners may no longer be the right tool.
That is when loppers come in handy.
The longer handles give you considerably more leverage for cutting thicker branches.
One good rule around here is simple: if you are squeezing the pruners with both hands and making faces while you do it, go get the loppers.
Once a butterfly bush develops thick woody stems, hand pruners may no longer be the right tool.
That’s when loppers come in handy. The longer handles give you more leverage for cutting thicker branches without fighting the plant.
One good rule around here is simple: if you’re squeezing the pruners with both hands and making faces while you do it, go get the loppers.
Disclosure: This post may contain affiliate links. If you make a purchase through one of these links, we may earn a small commission at no additional cost to you. It helps support the work we do at Bobby & Lynn’s Plant Farm.
Should You Prune Butterfly Bushes in Fall?
We generally recommend saving major butterfly bush pruning for late winter or early spring.
There is little benefit to cutting an established butterfly bush all the way down in fall.
Leaving the old stems through winter also gives you some extra material protecting the crown during periods of cold weather.
If a branch breaks or becomes damaged, you can certainly remove it.
Just save the major yearly cutback for the appropriate pruning window.
Can You Prune a Butterfly Bush Too Early?
Yes.
An unusually warm spell during winter can sometimes make plants begin waking up before winter is actually finished.
A hard pruning followed by warm weather can encourage tender new growth.
If another severe freeze follows, that growth may be damaged.
There is usually no prize for being the first person in the neighborhood to prune a butterfly bush.
Watch the plant and the weather rather than relying solely on the calendar.
Can You Prune Butterfly Bushes Too Late?
Butterfly bushes are forgiving, so pruning a little late usually will not destroy the plant.
However, once the shrub has produced a lot of new spring growth, a hard pruning removes growth the plant has already spent energy producing.
It can also delay flowering.
That is why late winter through early spring remains the easiest window.
Do Butterfly Bushes Bloom on Old Wood or New Wood?
Butterfly bushes generally bloom on new wood.
That means this year’s flowers develop on stems produced during the current growing season.
This is an important difference between butterfly bushes and shrubs that bloom from flower buds formed the previous year.
It is also why you can prune an established butterfly bush fairly hard in early spring without removing the summer’s entire crop of flower buds.
Should You Deadhead Butterfly Bushes?
Deadheading is different from the major pruning we do in late winter or early spring.
During the flowering season, you can remove faded flower clusters to tidy the plant and, with some cultivars, encourage additional flowering.
You do not need to cut the entire shrub back every time the flowers fade.
Think of the two jobs separately:
Late winter or early spring is for major pruning.
Summer deadheading is for removing spent flowers and keeping the shrub looking tidy.
What to Do After Pruning
Once you finish pruning, pick up the cut stems and take another look at the shrub.
You should have a much cleaner framework than when you started.
As temperatures warm, watch for new shoots developing along the remaining stems and around the base.
There is no need to panic if your neighbor’s butterfly bush begins growing before yours.
Different cultivars, microclimates, and even different spots in the same yard can wake up at slightly different times.
Give it a little time.
A Simple Butterfly Bush Pruning Rule
If you remember only one thing from this article, remember this:
Prune butterfly bushes in late winter or early spring, before strong new growth gets underway.
Remove dead growth first, clean out weak or crowded stems, then shorten the healthy stems to encourage vigorous new growth.
The plant may look bare when you finish.
By summer, you probably won’t recognize it.
Get a Reminder When It Is Time to Prune
Remembering which plant needs pruning in which month can become confusing pretty quickly.
That is one reason we created our free Garden Help by Bobby & Lynn app.
You can turn on push notifications and receive seasonal reminders for things such as pruning, watering during extreme heat, fertilizing, and other timely plant-care jobs.
There are no ads and no popups, and you can turn the notifications on or off whenever you like.
When our butterfly bush pruning reminder goes out in late winter, it can bring you directly back to this guide so you do not have to remember all of this until then.
