How to Prune a Butterfly Bush in 7 Easy Steps

Butterfly bushes have a beautiful vase shape. Their long, brightly colored flowers accent the arching habit of this plant and are sure to stand out in any garden. 

One of the main reasons you want to prune your butterfly bush is to promote blooming. This perennial will grow and bloom without pruning. However, the branches will become leggy, and the flowers will only bloom at the tops of the branches, making the plant a bit unsightly.

Fortunately, pruning this shrub is a very simple task. All you need is a little prep work to get started. If you are new to pruning Buddleia, follow along with me to learn some easy tips for getting your flowering shrubs into shape in no time. 

Gather Your Tools and Make a Plan

Before you get started, it is a good idea to make a plan for how you are going to prune. Will you cut the shrub all the way to the ground, or will you do a small pruning that only removes the tips of the branches?

Whichever type of pruning you choose, you will want to start with some nice clean tools. Bypass pruners and loppers are the best tools for the job. You may also want gloves and a bucket or a wheelbarrow to keep your hands safe and make clean-up a breeze. Let’s talk about the types of pruners you may want to use:

Best for Small Branches: Bypass Pruners

This pruner is my go-to tool for deadheading or trimming herbaceous perennials and branches with a smaller diameter. Bypass pruners are small and fit comfortably in your hand. If you keep your pruners in good shape, they will make nice clean cuts for you without much effort.

Best for Large Branches: Loppers

Loppers are great for tackling larger jobs or jobs that may be overhead and just out of reach. These large tools use a scissor motion to cut away larger branches. Loppers are best for branches with a larger diameter.

Always clean and sanitize your tools before use. This will prevent cross-contamination of any diseases that your snips may have encountered the last time you used them. 

Get Your Timing Right

It is very common for flowering shrubs to be pruned in the fall.  However, the best time to prune your butterfly bush is in the late winter or early spring, after you see some new growth appearing on your plant. You will want to wait until the spring and not tackle this task in the fall because pruning the shrub too close to winter will leave the plant vulnerable to frost damage.

When plants experience a cold frost, the exposed cells of new tissue collapse due to the amount of water freezing within the cells.

Your older stems may collect water in their hollow center and split with the freezing and thawing of water. You may not miss out on flowers entirely, but your blooms will likely weaken and appear much later in the season. 

While it is important not to prune too late in the fall, it is equally important not to prune too early in the spring. We have all experienced an unexpected late frost that wipes out our early spring growth. Wait until you see your shrub producing new growth. 

Look for New Growth 

Butterfly bushes bloom on new wood. New wood is growth that is fresh and new in that growing season. Look for new growth near the base of the plant. What you should see will be very familiar. Look for fresh green buds, green stems, and green leaves. 

It is crucial to remember that these plants leaf out later in the spring. Do not panic if the rest of your shrubs and perennials show signs of life and your butterfly bush still appears to be hibernating. 

Once you see a good amount of healthy leaves, you will be in the clear to begin your pruning. Cutting back your shrubs too early could result in a flowerless summer for this perennial.

Remove Dead Stems

Look at your plant and locate some older or dead stems. There may be dead or damaged stems on your butterfly bushes for many reasons. They could just be old or have snapped during a storm. You want to cut these branches back to the ground or at the point of breakage.

These stems should be easy to find once your plant starts to produce its new spring growth. Look for stems that do not appear to have any buds or leaves on them. Occasionally, deadwood will wiggle out of the base of the plant if it has been dead for a while. 

Begin Your Pruning

Once your dead stems are out of the way, it is time to get to work. Make a nice clean-angled cut just above where the leaves appear. This is usually around one foot from the ground.

Don’t stress about pruning “correctly”. These flowering shrubs are vigorous growers, and any small mistake you may think you have made will erase itself within the growing season. 

Depending on the variety, you may not need severe pruning. Many dwarf varieties do not require much, if any, pruning. You can typically prune dwarf varieties with small bypass pruners and remove the longer stems.

If you are not doing a major prune, you may only want to trim back some lateral branches to improve the overall shape. Follow the lateral branch back to its leader (the larger branch) and snip it away. New leaves should form here, and your bush should resume its beautiful vase shape shortly.

Check Your Work

Once you have finished pruning and removing dead stems, take a nice walk around your plant to see if you are happy with your work. Pruning serves two purposes:

1. to improve the vigor of the plant and encourage new growth
2. to improve the overall shape and appearance

Make sure everything looks even, and you don’t have any long straggler stems. It is always safer to cut twice than to cut once and cut too much off.

The good news is that if you cut too much below the new growth, your shrub will be safe. It just may not fill out as nicely as it would have if you had made your cuts above the new leaves. This is because you will have removed a good amount of new growth by removing any new leaves. 

Don’t Forget to Deadhead

Don’t forget to deadhead the spent flowers to keep your butterfly bushes flowering all season long. The flowers produce a lot of seeds and can become invasive. Knowing if this flowering shrub is invasive in your area is important. If it is, there are a lot of seedless varieties that are available.

Deadheading your butterfly bushes is easy: Simply snip the flower off the branch as close to the next cluster of flowers as you can get. This will leave a small wound that will heal easily and will not leave any unsightly gaps in your shrub.