Butterfly bush (Buddleia davidii), often referred to as buddleia, is a flowering perennial that forms clusters of fragrant, colorful flowers. True to its name, the butterfly bush is a butterfly magnet that also attracts bees, ladybugs, hummingbirds, and more. However, it is an invasive plant that can be very difficult to control. Fortunately, plant breeders have developed some sterile cultivars, which are the best ones to plant in a home garden. Consider the pros and cons of butterfly bush before deciding whether to add this plant to your garden.
Butterfly Bush Pros and Cons
Butterfly bush has a bit of a reputation among gardeners. Some love this plant for its color and appeal to beneficial garden bugs, but those who have struggled to eradicate an invasive butterfly bush completely revile them.
Pros of Growing Butterfly Bush
There are several reasons to grow buddleia, which is why--despite its reputation for being invasive--butterfly bush continues to be a popular plant.
- Pretty, long-lasting blooms
- Attractive to wildlife, including monarch and swallowtail butterflies, hummingbirds, bees, and ladybugs
- Resistant to deer and rabbit damage
- Unique cut flower that lasts a long time in a vase
Cons of Growing Butterfly Bush
Of course, buddleia also has a few cons that are worth considering before you add this plant to your garden.
- Black knight, the most common butterfly bush variety, is invasive. It is even illegal to sell in some states.
- Where invasive varieties are not illegal, they are still sold in nurseries and plant markets.
- Some cultivars take up a large amount of space in the garden, so they can shade out other plants.
Growing Butterfly Bush in Your Garden
If you're still interested in planting butterfly bush, you'll be glad to learn that it's not difficult to grow. These flowering shrubs can grow to between six and 12 feet tall and spread from five to 15 feet wide. They have unruly, drooping branches, so they tend to look best in a casual setting rather than a formal one. They thrive in many types of soils and are generally hardy in USDA Zones 5-10. If you are going to grow butterfly bush, it's best to plant a sterile cultivar rather black knight or a wild plant.
Where to Plant Butterfly Bush: Light and Soil Requirements
Butterfly bushes prefer a site with full sun to partial shade and well-drained soil. These plants thrive in just about any kind of soil, but they are prone to root rot. If you have heavy clay soil or a spot that stays wet, butterfly bush likely isn't a great choice for that area. Of course, you can amend clay soil to make it more hospitable to plants. Spring or fall is the best time to plant butterfly bush plants.
- Loosen the soil to a depth of about one foot, then mix in a four-inch layer of compost.
- Dig a hole twice the size of the pot that the plant is in.
- Remove the plant from its container and place it in the hole so that the top of the rootball is level with the surface of the soil.
- Fill in around the rootball and water thoroughly.
Watering and Fertilizing
During dry spells (and especially during the plant's first year, when it's getting established in your garden) be sure to water deeply. In general, after the first year, butterfly bushes need only about an inch of water per week. Once established, they handle drought pretty well. These plants really don't need to be fertilized unless they're planted in very poor, low-nutrient soil. A topdressing of compost around the plant each spring is really all it needs to be happy.
Butterfly Bush Blooms
Fragrant blooms begin to appear on butterfly bush shrubs in July and continue prolifically until frost. It is important to remove the dead flower clusters because, unlike other plants, the flowers will not drop on their own. Removing spent flowers is extremely important if you don't have a sterile variety, as these plants reseed prolifically. Volunteer seedlings can easily take over and choke out other plants, which is why these plants are considered invasive. Be sure to pull up the seedling as you find them.
Pruning Butterfly Bush
If you are growing black knight or any other invasive variety, deadhead very carefully. Be sure to remove all spent flowers before they can go to seed. This will help prevent the plant from spreading. Pruning requirements for butterfly bush vary based on how cold your area is. Do not prune during summer or spring.
- Warm zones: If you live in a warmer zone (USDA Zone 7 or higher), this plant won't die back at all. It will continue growing, blooming on the current year's growth. In this type of climate, butterfly bush can grow to have a spread of up to 15 feet. To keep it under control and prevent it from shading out nearby plants, you might have to prune it back. This is best done in late winter before new growth starts. Alternately, you could cut back the entire plant in fall; it will sprout back from the roots just as any perennial would.
- Cold zones - If you live in USDA Zone 5 or 6, your butterfly bushes will likely die back each year and sprout new branches from the base of the plant the following spring. In this case, the only pruning you have to do will be to remove dead or damaged branches or to cut off spent blooms in the fall or winter. If you live in an even colder zone, you can still grow this plant, but you'll need to mulch deeply with fall leaves or evergreen branches in late fall or early winter to prevent the roots of the plant from being damaged by the cold,
Butterfly bush is a notoriously slow starter in the spring, so don't be quick to assume the plant didn't make it through the winter. Once it gets going, it will grow quickly.
Butterfly Bush Pests and Diseases
Butterfly bushes don't have many pests or diseases, though there are a few concerns to keep in mind.
- Yellowing leaves are a common symptom of root rot. If this happens, cut back on watering right away. Dig the plant up and amend the soil with organic matter (if the soil is very heavy) or move it to a different spot in your garden.
- Japanese beetles sometimes feed on the leaves of butterfly bushes. If you notice that the leaves have holes or look otherwise nibbled on, inspect the plant and pick off any beetles. You may need to take further measures to get rid of Japanese beetles.
Propagating Butterfly Bush
Both invasive and sterile butterfly bushes can be propagated using the cutting method, which involves snipping off pieces of a plant and rooting it. This is the only option for sterile butterfly bushes, though you should be certain that the cultivar you are working with is not patented before you decide to take cuttings to root. Invasive butterfly bush plants propagate all too easily by seed, but their offspring are often are not the same color as the parent plant.
Beautiful Butterfly Bush to Grow in Your Garden
While black knight and any wild Buddleia davidii plants are invasive, plant breeders have developed several varieties that have the attractive blooms and pollinator-attracting qualities of the native version, without the danger of having the plant take over your garden. A few good ones to consider include:
The Miss Pearl cultivar blooms in pure white and grows to about five feet tall by five feet wide.
Miss Molly produces vibrant pink flowers on plants that grow up to five feet in width and height.
Lo and Behold
Lo and Behold is a line of compact butterfly bushes, available in colors like blue, purple, pink, and white. They grow to be about two feet tall and wide, so they're perfect for smaller gardens or containers.
Flutterby is also a line of small butterfly bushes that grow to about two and a half to three feet tall and wide. This cultivar also comes in blue, purple, pink, and white. They also work great in small gardens or containers.
What to Plant With Butterfly Bush
Butterfly bushes do offer nectar to bees, hummingbirds, and adult butterflies, but that's about all they offer in terms of wildlife habitat. If you're trying to provide a haven for butterflies, you'll also need to include plants that serve as host plants for the adults to lay eggs on, as well as plants to provide food for the caterpillars.
Trees and Shrubs
Consider planting trees and/or shrubs that serve as host plants or food sources for caterpillars near your butterfly bushes.
Annuals and Perennials
Of course, annuals and perennials are an essential part of any wildlife habitat or pollinator garden. The ones listed below are pollinator magnets.
How to Get Rid of an Invasive Butterfly Bush
If you have an invasive butterfly bush and you want to get rid of it, the only way to do so is to dig the plant up, getting as many of the roots as possible. You'll also have to be careful about how you dispose of it. If you compost this overly-enthusiastic plant, chances are good that it'll just start growing in your compost pile. Burying it won't work; it'll most likely work its way up to the surface again.
- Burning: This is a good option, and will ensure that the plant can't spread anywhere. Just keep local ordinances and safety in mind.
- Smothering: Once you dig the plant out, if you can't burn it, consider placing it in a double-bagged black trash bag. Set it aside for a few months. After several months of no light or water, the plant should be dead. You can compost it at that point.
- Municipal collection: Some cities and towns have methods for helping homeowners dispose of invasive plants. If butterfly bush is invasive or illegal to grow where you live, check with your municipality to find out how you should dispose of it.
Choose Wisely and Enjoy
Butterfly bushes are an attractive addition to the landscape, but the wrong variety can do more harm than good. Choose a non-invasive, sterile variety, and, if you're removing an invasive one, do so carefully to ensure it doesn't spread further.