When Should I Prune a Butterfly Bush and How (Buddleja davidii)

Buddleja davidii or butterfly bush blooms throughout the summer and part of the fall on the branches that are born in the same year, from spring. In this article, we will explain When Should I Prune a Butterfly Bush (Buddleja davidii) and How to do it, to maintain abundant flowering in spring and summer and take care of the plant during the cold winter from the first frost.

Butterfly Bush Buddleja davidii

Butterfly Bush (Buddleja davidii)

Butterfly Bush (Buddleja davidii) is a very grateful shrub. It is not prone to disease and tolerates quite well with little watering, it is not at all delicate in terms of soil as the only thing it hates is waterlogging and too much moisture. On the other hand, it grows best in well-drained soils and very sunny locations.

Although they say that it has some resistance problems, I must clarify that the ones that I have cultivated in my previous garden as well as in this one (and in both, it freezes frequently) have not presented any resistance problem to the low winter temperatures.

It is one of the longest flowering shrubs. They begin to bloom in summer and remain in bloom well into autumn.

The many existing varieties allow you to choose between many colors ranging from white to mauve, blue, pink, and even some yellow … It is also worth noting its delicious aroma that reminds me a lot of the smell of honey.

Butterfly Bush Buddleja davidii hardiness zones from 5 to 9 as Red plume, purple haze, White bouquet, Inspired Violet, Flutterby Petite™, Tutti Fruitti Pink, Blue Chip Jr.,
Butterfly Bush (Buddleja spp.) blooming in USDA hardiness zones from 5 to 9 as Red plume, purple haze, White bouquet, Inspired Violet, Flutterby Petite™, Tutti Fruitti Pink, Blue Chip Jr., etc.

Buddleja Varieties Attracting Bees and Butterflies

Buddleja Varieties Attracting Bees and Butterflies. There are many varieties of Buddleja spp. with different colors and colorful that will thrive in hardiness zones from 5 to 9 as Red plume, purple haze, White bouquet, Inspired Violet, Flutterby Petite™, Tutti Fruitti Pink, Blue Chip Jr., etc, etc.

Of all its characteristics but has one that I love the most: its ability to attract bees but especially attract butterflies. During the summer it is common to see how these insects flutter around it, landing on its inflorescences. They irresistibly attract them and it is a pleasure to spend time during their bloom observing the many types of butterflies that come to perch on their flowers. You don’t know which is prettier, the flower or the butterfly.

Butterfly Bush Location in Your Garden

The Butterfly bush reaches a considerable size in a very short time. Even if they are subjected to intense pruning, their branches grow rapidly during the spring. During the summer/autumn they quietly reach 10 ft (3 meters) in height. By this time the branches have grown enough to arch beautifully.

I would advise locating this shrub with its growth type in mind. When I planted it, I had no idea of the size it was going to acquire in a short time and the truth is that it did not have enough space to show off its arching branches. The fact that it was bordered at the back prevented it from looking as it does when it has enough free space around it for its branches to arch in all directions presenting a very beautiful outline.

When to Prune a Butterfly Bush

Many readers write to us asking “When do you prune a Butterfly Bush?”. In the following paragraphs, we review and explain When Should I Prune a Butterfly Bush and How to do it.

Summer & Autumn Cleaning Pruning for Butterfly Bush

When should Butterfly bushes be trimmed? In Summer and in Autumn we are going to do a Cleaning Pruning for Butterfly Bush. The very long branches bloom initially at the end but later also on the side branches of these main stems that sprout almost from the base of the plant.

If we cut these flowers as they fade, we will prevent them from spending useless energy forming seeds and we will favor that the lateral branches have more energy to form more flowers.

when should i prune a butterfly bush how to prune
How and When to Prune a Butterfly Bush

Annual Pruning of Butterfly Bush – End of Summer

Annual Pruning of Butterfly Bush – End of Summer. At the end of winter or the beginning of spring, as soon as we see that it begins its vegetative activity, it will be the moment to practice the annual pruning.

Let’s dive into When Should I Prune a Butterfly Bush and How to do it.

How to Prune a Butterfly Bush in the First Year

In the first year, it is advisable to cut back all the stems that emerged the previous season. This will favor the sprouting of many new stems from the base from spring onwards, which when summer arrives and they are mature will produce green sucks, new branches, and flowers.

If when we practice pruning, we see that the plant is already emitting some strong branches from the base, we will leave them as they will grow rapidly during the spring and then bloom in summer/autumn.

When Should I Prune a Butterfly Bush and How to do it
When Should I Prune a Butterfly Bush and How to do it in the first year

How to Prune a Butterfly Bush from the Second Year and So On

From the Second Year On

We will practice first a maintenance pruning that will consist as always:

  • Remove all dead wood
  • Any branches growing towards the interior of the shrub.
  • Weak or diseased branches

What Should I do After Cleaning Pruning

Let’s see What to Do After a Butterfly Bush Cleaning Pruning. After this cleaning we can choose between two options:

  1. Maintain a “structure” that will form the base of the plant. That is to say, cut at about 24-28 inches (60-70 cm) from the base of almost all the stems. It will be from this height that we can where will come out most of the shoots that will form the branches. Keep in mind that old wood has little ability to re-sprout. This option creates a bush with a clearer base in which we can grow a small plant of little height (that can live near the powerful roots of this plant).

These thick, old branches that we keep a little more than half a meter above the ground will quickly thicken and lignify, losing their vigor.

That is to say, when you want to give the shrub a less leafy base and the branches to be higher up, you will leave more height on the stems when pruning. This option forms taller shrubs in less time.

  • The other option is that this “structure” does not gain too much height with annual pruning. That is, prune all the branches to about 10-12 inches (25-30 cm) from the ground or a few centimeters from the birth of the old branches.

With this option, Buddleia emits branches from lower down and is leafy at the bottom.

This way of pruning this shrub causes the season’s new branch growth to start much lower so that the base of the plant does not look so bare.

The only drawback to this way of pruning is that the branches, which are quite long, tend to arch with the weight of the flowers and some people find the shrub more harmonious if the branches start from a greater height as it allows more length to look arched without touching the ground.

This type of pruning is similar to that of Crepe Myrtle tree pruning.

How and When to Prune a Buddleja for winter

Pruning a Buddleja davidii After A Few Years

Pruning a Butterfly Bush After A Few Years. In the following years: pruning to rejuvenate (whether we choose to keep a somewhat high structure as a base or not) we must keep in mind that we will have to remove almost from the base some of these stems that are thickening a lot and that the older they are, the less vigorous they are and the less they will flower and emit side shoots that become other long branches…

By removing some of these thick, old branches each year we will keep the shrub rejuvenated and prevent the shrub from becoming overly lignified and aging and forming a tangle of branches that produces a rather neglected appearance and will flower less and less.

Buddleia stems thicken from year to year and age early. The capacity to re-sprout and emit more branches decreases as the years go by (as in many shrubs).

Keep in mind that when we eliminate old branches almost touching the ground, we should leave a few centimeters of them that will die during the summer and that we can easily eliminate. If we cut to the ground they will die to the root and will not emit young stems at their base.

Finally, the most important piece of advice in this post is about When Should I Prune a Butterfly Bush and How to do it. Remember that Buddleja davidii is a quite invasive plant in different countries such as the UK, Spain, France, Australia, and New Zealand as well as many states of the USA and displaces other native species. It is not superfluous to know this and to take special care if we already have these plants in our gardens and for whatever reason, we want to get rid of them, do not throw them away without destroying them first.

About Julia Morgan

We are the Morgan family, Henry, and Julia, both agronomists from the University of Michigan, where we met. We are experts in putting our hands in the soil and developing organic foods and improving production processes for decades. Likewise, we have worked for companies such as Mondelez International, BASF, Monsanto, etc. currently in our role as science writers for TheGardenStyle.com as well as advisors in promoting large scale food growing in urbanized areas. In this website, we share what we are most passionate about, gardening and farming. Enjoy and see real photos on our website. We hope that all our advice will be useful to you and that you will become an expert gardener.