The Mid-March Cutting Back of Buddleias

It’s mid-March, and what does that mean? Well, among other things such as dreaming of pots of gold and being careful to avoid getting swept up by the wind, it means it is time to cut back Buddleias, gardeners’ beloved Butterfly Bushes, which are generally well-suited to being grown in USDA Plant Hardiness Zones 5-9.

With this being the Year of the Buddleia per the National Garden Bureau, Buddleias seem to be on the minds of many gardeners. But I am quite convinced that we all do not know exactly if and when we should cut back these shrubs to ensure full growth and evenly distributed blooms. I am convinced of this because, for the longest time, I surely did not know. I often avoided doing any cutting back of these pretty pollinator drawing cards, simply because I did not want to do them harm.

Cutting Back: To Do or Not To Do?

So what is the scoop on ensuring that Buddleias stay looking and performing their best? Does optimal care involve annual cutting? First, it seems vital to share that cutting back Buddleias is indeed important. It truly improves these lovely shrubs. Now, lately I have noticed that growers are proud to share that cultivars of all sorts of plants can be left to self-clean (no deadheading involved) and will not need to be cut back. But most of what I have read about Buddleias indicates that a harsh late-winter/early spring cutting is key, no getting around it.

The Buddleias in my garden surely need deadheading all summer to maintain a tidy look. Their tan or grayish spent blooms take away from the attractiveness of newly opened flowers. And this deadheading must be done with care, considering the way tiny new bloom-tipped stems shoot out in opposite directions just below a central flower cone. Cut too quickly and too far down along a stem, and you will lose flowers that were yearning to greet you.

But that’s deadheading. What about cutting back these shrubs? In autumn, Buddleias should be left alone. Their stick-like stems will lose their leaves and appear quite dry, turning the shrubs into grayish ghosts of what they looked like in summer. These shadowy forms are not an eyesore in the winter garden; instead, they help the gardener to recall the locations of these deciduous shrubs in the winter landscape. 

Heavy snow can take down some of the bare stems, but for the most part, they remain in place until spring. If these stems are not cut back in late March or early April, the new blooms of summer may congregate at the terminal ends of the stems. If you have seen a Christmas tree with all the ornaments at the very tips of its branches, you will be familiar with this look. It is likely that you will yearn for a better (all-over) distribution of flowers, and this comes courtesy of a harsh cut-back at this time of year. This cut-back will also help to prompt fuller stem and foliage growth when the warm weeks arrive.

To What Extent Should Buddleias Be Cut Back?

A harsh cut-back? Well, how harsh is harsh? I like to cut my Buddleias down to about half-a-foot above the spring soil. Some recommend cutting even lower than this, right down near the woody base of the plant and just above the top of the soil. Neither approach can hurt the shrub, and you will be surprised at how quickly your Butterfly Bush can regain the height and spread that it achieved during the previous summer.

With cutting back to less than a foot, damaged parts of stems are removed, dead stems that have snapped and are just “hanging out” can easily be removed, and the Butterfly Bush gets sent a signal that it is time to grow… to grow fresh and full, and with blooms scattered here and there at multiple levels rather than exclusively at the ends of stems. Moreover, this early spring pruning will help the summer flower buffet to get set up just a little later in the season, when the pollinators need it most.

Summing Up

If you live in a climate in which Butterfly Bushes can thrive in summer and return for summers on end, then like me, you are fortunate. We know firsthand why it is the Year of the Buddleia. The Buddleia is a wonderful garden addition. But if these shrubs are too tender for your region, you can take heart in the fact that there are countless other shrubs and perennial plants that draw in pollinators with colorful blooms and sweet scents. Plenty of these other shrubs are just a bit hardier, and they are ready to make butterflies, bees, and hummingbirds happy in your neck of the woods. In either case, it may help to know a little about the pruning needs of this flowering shrub, as understanding those needs can be helpful in determining how to handle other shrubs that bloom on new wood.

When I think of caring for my Buddleias, I realize how easy they are to grow. Not much needs to be done with them mid-summer, aside from deadheading. In fact, one of the worst things to do with them is to add fertilizer to their soil. They need good drainage, but they want no pampering. But one thing I have come to know is that cutting them back now, in late March or early April, makes all the difference in how they will look and perform when the warm weather arrives.

So, it's mid-March. Sure, check for the rainbow; keep an eye out for the pot of gold… but don’t fail to cut back your Buddleias now, when the timing is right. In summer, you might possibly find them to be more precious than gold.