When you planted your Buddleia, you probably knew you could expect it to get pretty big. But how long will that take? And how tall will your plant be by the end of the growing season? Lots of genetic and environmental factors can affect the rate of Butterfly Bush growth, not to mention its final size. But as a rule, you can expect it to get big in a hurry.
A Butterfly Bush will almost always grow at least two feet per year and sometimes as much as five to six feet! The mature size of a Butterfly Bush varies depending on the variety, but many Buddleias can exceed six feet in height, and some may grow 12 feet tall or more.
Give your Butterfly Bush plenty of room to spread out because it’s not uncommon for them to be even wider than they are tall. This is one reason these plants are so popular — they’re a fantastic way to fill out a bare-looking garden. This article will help you understand what to expect from your Butterfly Bush in terms of growth, height, and lifespan.
How Fast Will a New Butterfly Bush Grow?
Buddleia Davidii, the Butterfly Bush, is a stupendously fast grower. Once these plants are rooted and established in your garden, they can put on a huge amount of height in a year. In cold climates, they routinely die back to stubble every fall. By the time the next summer draws to a close, they can easily be six feet high again.
A newly-planted Butterfly Bush will likely grow a bit slower since it has to establish its root system before the foliage can really take off. But it should still gain a decent amount of height even in year one. Even if you’re planting a tiny specimen sold in a four inch pot, it’s not unreasonable to expect it to gain two feet in its first year.
And yes, you’ll most likely see flowers even during year one! These plants bloom readily and abundantly when their needs are met.
How Big Can a Butterfly Bush Get?
If you live in a colder climate, you may never see your Butterfly Bush at its full size. This shrub is prone to severe winter dieback, though the roots will generally survive and spring back with a vengeance. In that case, the maximum height it will reach is around six to eight feet tall (unless you choose a dwarf cultivar).
Those who live somewhere that stays mild year-round may see some truly spectacular Butterfly Bush growth. When it’s not slashed back repeatedly, one of these plants can easily stretch up to 12 feet tall. Some have even been known to exceed 15 feet. These larger Butterfly Bushes often become woody and can be shaped to resemble small trees.
The taller types of Butterfly Bush are usually a foot or two taller than they are wide. Dwarf varieties tend to be rounder, with their width equaling or slightly exceeding their height.
What Are the Biggest Varieties?
Taller Butterfly Bush variants include:
- Black Knight. Sometimes spelled “Black Night”, this Buddleia has deep purple flowers and tends to reach six to eight feet in height.
- Attraction. This cultivar has deep pink blossoms that sometimes appear almost red. It routinely exceeds six feet.
- Honeycomb. True to its name, the Honeycomb has clusters of vivid yellow blooms that look a bit like the segments of a beehive. It grows around five to seven feet tall.
- White Profusion. Not only are the flowers bright white, but the undersides of the leaves also have a silvery sheen thanks to the fine hairs coating them. This shrub typically reaches six to eight feet at maturity.
- Grand Cascade. This six foot tall variant is especially notable for its enormous cones of flowers, which grow 12-14 inches long and cause the stems to drape down under their weight.
- Royal Red. The vivid reddish-pink blooms of this cultivar are also quite fragrant. It can reach eight feet tall every summer, even if it’s cut back every fall.
When Will Your Butterfly Bush Grow To Its Mature Height?
The answer to this question may depend on exactly how large of a variety you’ve chosen. However, most Buddleias can reach their mature size within two years. The bigger cultivars by the end of year two. Keep in mind that the official mature heights of many cultivars are based on the assumption that you’ll be pruning the plant heavily. Though most Butterfly Bush’s growth rates will slow down once they’re about eight feet tall, they may not stop entirely. If your plant doesn’t die back in winter and you leave it alone, it could eventually hit the 15-foot mark.
When Will You See New Growth on Your Butterfly Bush?
It’s springtime, and shrubs and trees all throughout your yard are bursting with new leaves. But your Butterfly Bush remains stubbornly lifeless. When should you expect it to start putting out new growth?
In warmer areas, you might see your plant extending new growth as early as March. In places with hard winters, though, it’s quite common for Butterfly Bush growth to begin later than most of your other plants. It’s not unheard of for them to wait until May or even early June.
Hard pruning may also delay the emergence of new growth, especially in conjunction with a very cold winter. Don’t worry, though; your Butterfly Bush should quickly catch up to the rest of your garden (and probably overtake it). Pruning only increases the vigor of the new growth once it gets going.
How Can You Get the Best Butterfly Bush Growth Rate?
If you’re interested in growing your Buddleia to epic proportions, what can you do to speed it along? For the most part, these shrubs need very little encouragement, but the following tips will help:
- Provide lots of sunlight. The most robust Butterfly Bush growth happens in full sun. Your plant can tolerate partial shade, but it will be happiest and most vigorous when it’s drenched in light. Avoid placing it somewhere too dark.
- Water thoroughly. A fast-growing plant needs a steady supply of water to keep it going. Give your Butterfly Bush plenty of hydration, particularly during its first growing season. Don’t overdo it, but make sure to water when the upper one to two inches of soil dry out.
- Prune your plant. It’s not strictly necessary to take the loppers to your Butterfly Bush every year. However, it does spur fast and vigorous growth. It might sound odd to advise cutting back your plant to get it to grow big, but there’s no need to chop it all the way down to the ground. Trimming off a few feet each winter should encourage lots of new growth and blooms the following year.
- Provide nutrition. In most soils, Buddleias can grow perfectly well without added fertilizer. But adding two to four inches of compost around the base each spring should help ensure it’s got what it needs to grow. If you really think that your plant is growing too slowly, you can use some slow-release granular fertilizer instead. Start with ¼ or ½ of the dose on the packaging first to see if that does the trick.
How Long Will Your Butterfly Bush Live?
Ever heard the expression “Live fast and die young?” That could be the motto of the Butterfly Bush. Though they are perennials, these fast-growing shrubs typically don’t stick around for the long haul.
A well-tended Butterfly Bush may live up to 20 years, but ten is more typical; it’s simply not a very long-lived plant. The good news is that it should be extremely easy to replace your Buddleia when it’s near the end of its lifespan. They produce tons of seeds, and getting them to sprout and grow is fairly simple.
Will Your Plant Grow Out of Control?
You might have heard that Buddleias are considered an invasive species in some regions. Do you need to worry that it will take over your entire garden? Not exactly. The problem with Butterfly Bush growth isn’t that this plant creeps across everything in its path like kudzu. The seeds are what you need to watch out for.
A Butterfly Bush can produce a huge crop of seeds. A single flower spike may contain up to 40,000 of them! These seeds are small, lightweight, and equipped with little wings to let them travel in the breeze. They can spread long distances, and if they escape your yard, they may choke out other native plant species.
You can prevent this scenario by diligently deadheading your Butterfly Bush. As soon as you see the flowers beginning to wilt and die, grab your pruning shears and some rubbing alcohol. Clip off the flower clusters before they have time to set seed, disinfecting your trimmers between cuts. Luckily, your Butterfly Bush has a long blooming period. So you should still get several months of beautiful color before you have to chop off the flowers.
Final Thoughts
Butterfly Bush growth is almost scarily fast. An established Buddleia can go from a few stubs poking out of the ground to a six-foot-tall monster in a single growing season. You don’t have to do much to make this happen, but the right amount of sun, water, and nutrition will help. If you can meet those needs, you should have a robust Butterfly Bush in no time!