How to Prune a Butterfly Bush

Co-authored by Lauren Kurtz

Last Updated: November 6, 2022 Approved

As the name might suggest, butterflies absolutely love Butterfly Bush for its showy, fragrant, nectar-rich flowers--and so will you! The flowers of this tall bush make a gorgeous addition to any garden. However, to keep these bushes blooming beautifully, you will need to know how to prune them properly. Scroll down to Step 1 to learn how you can properly prune your Butterfly Bush.

Part 1

Part 1 of 2:

Pruning Your Butterfly Bush

1
Wait for the right time of year to prune. There are two types of butterfly bushes: Buddleia davidii and Buddleia alternifolia.
- Buddleia davidii is a deciduous shrub with dark purple flowers that blooms June through September. This butterfly bush is classified as an invasive plant is some parts of the United States. You can check if it's an invasive species in your state by visiting https://plants.usda.gov/java/noxious.
- Prune your Buddleia davidii in early spring or late winter. Pruning is best done before new growth starts in the spring. In climates with cold winters, the plant will most likely die back completely.
- Buddleia alternifolia (Alternate leaf butterfly bush) is a deciduous shrub with light purple flowers in the spring.
- Buddleia alternifolia should be pruned in mid to late summer, right after it has bloomed. This kind of butterfly bush blooms on stems from the previous year, so cutting it to the ground each year is not an option.
2
Look for any dieback. Dieback is caused by harsh winters or disease. In this case, a particularly cold winter could cause dieback in your butterfly bush. When a plant dies back, the tips of the leaves or roots begin to die, slowly leading to a reverse death that ends in the death of the whole plant. Dieback is common in butterfly bushes in colder climates--butterfly bushes often dieback all the way to their roots in very cold winters. However, this does not mean that they cannot be saved--that’s what pruning is for.
- Butterfly bushes are late to break dormancy, meaning that you don’t need to check for any winter damage as the plant may still just be dormant.
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3
Prune your butterfly bush. How you prune your butterfly bush will depend on which type of bush you're growing.
- If you have a Buddleia davidii, prune it with a hard cut. Because they do often dieback in the winter, this type of butterfly bush can handle intense pruning--and often requires it. Even if your butterfly bush doesn’t dieback during winter, prune 6”-12” above the ground in late winter to ensure proper growth the following spring.
- If you have a Buddleia alternifolia, prune your bush back hard to about ⅓ of its size immediately after it flowers in the early summer. Follow the shape of the shrub when pruning.
- If your butterfly bush is in the back of a garden up against a fence and you want it to grow tall, cut it back to about two feet so that the plant will produce higher growing (and thus flowering) stems. You will then be able to plant lower growing plants near the butterfly bush while still being able to see the flowers of the butterfly bush.

Part 2

Part 2 of 2:

Promoting Bloom Growth

1
Dead-head the spent blooms while the plant is flowering. This means that you should pick or cut the flowers that have died while the bush continues to bloom. Spent blooms will start to turn brown and will look very wilted. Cut the dead blooms back to where they attach to the stem. Doing this will ensure that your bush produce new flower buds longer into the blooming season than they would if the bush was left unattended.
2
Remove spent blooms at the end of the season. At the end of the season, you should dead-head all of the now finished blooms. This will help the plant along when creating buds for the next year. It will also limit the butterfly bush’s chances of self-seeding and thus taking over your entire garden.

Community Q&A

Question

What is the difference between a Buddleia davidii and the Buddleia alternifolia butterfly bush?

Community Answer

There are several differences between the Buddleia davidii and the Buddleia alternifolia. First, they are closely related but not the same exact plant.These plants are two different species. They have the same genus, buddleia but different species, davidii and alternifolia. They have different growth habits, maintenance requirements and aesthetics. Alternifolia grows up to 15’ and has light purple flowers. Davidii grows up to 8’ and has dark purple flowers. Their leaves are different colors and are spaced differently. Davidii has opposite leaves and Alternifolia has an alternate leaf arrangement. They also require different pruning strategies as outlined above.
Question

Is there a cure for a tomato plant fungus I have in my garden?

Community Answer

Water mixed with about 30% rubbing alcohol works very well against it.
Question

How far can I cut a bush back if it was neglected for a long time and has grown too high?

Community Answer

Depends on what type of bush it is, but a general rule when a shrub was neglected is to not harshly prune it, but to do it gradually over several seasons. If you’re unsure of the type of shrub you have, your best bet is to not trim more than a third of its total size.

Warnings

A Butterfly Bush is an invasive species in parts of the country, so make sure to burn trimming and branches or dispose of them in garbage bags.

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