The butterfly bush (Buddleia davidii) is a fast-growing, perennial shrub with masses of flowers—long, spiked trusses—that bloom from summer to autumn. While low-maintenance, butterfly bushes do need to be pruned in early spring. Learn more about growing this flowering shrub.
Also called “summer lilacs,” Buddleja are hardy to Zone 5 and remain evergreen from Zone 8 south. Growing 5 to 10 feet tall, this large, arching shrub produces an abundance of fragrant, showy flowers in mainly purple and pink. The shrubs grow well in perennial or shrub borders and the flowers are good for cutting.
Butterfly bush growth appears on new wood, so pruning can wait until the new wood is ready to grow in spring. Be patient with Buddleja since the shrub might not leaf out in the spring until after other perennials.
Please note that the butterfly bush, originally imported from China, has been classified as an invasive species in many U.S. states as its known to crowd out native plants that are essential to wildlife. In warm climates, it can become a noxious weed and spread aggressively, while in cooler climates, it mostly stays contained if gardeners deadhead the flowers.
Note: Despite its common name, butterfly bush is not a “host plant” for butterflies in that it does not support butterfly reproduction and lifecycle. Caterpillars do not feed on butterfly bushes; it only provides nectar to adult butterflies similar to many flowers. If you do have a butterfly bush, be sure to add native host plants such as milkweed, aster, and dill if you want the butterflies to stay. See plants that attract butterflies.
If you would still like to put a butterfly bush in your garden, there are a few species of non-invasive butterfly bushes native to the southwestern US. Please check with your local cooperative extension for more information.
Choose a location with full sun and moist, well-drained soil.
Loosen the soil from 12 to 15 inches deep and mix in a 2- to 4-inch layer of compost.
Dig a hole twice the diameter of the plant container.
When placing the plant in the hole, the top of the rootball should be level with the soil surface. Gently backfill the hole around the rootball. Firm the soil.
Caring for Butterfly Bushes
Water freely when in growth and sparingly otherwise. In the summer, water if rainfall is less than 1 inch per week.
Avoid fertilizing butterfly bush; too much fertility promotes leaf growth over flower production.
Remove spent flower spikes to encourage new shoots and flower buds. In addition, it is important to deadhead the flowers just as they start to wither so that this invasive plant doesn’t spread volunteer seeds. Deadheading of this invasive is now required in many states.
Each spring, apply a thin layer of compost, then 2 to 4 inches of mulch to retain moisture and control weeds.
In cold, Northern climates, spread mulch up to 6 inches deep around the trunk to nurture it through the winter.
Buddleias are very late to break dormancy, so don’t be in a hurry to assess winter damage.
The bush should bloom abundantly even in its first year. In warmer climates, the bushes will grow into trees and develop rugged trunks that peel; peeling is normal.
In the northern limit of their range, they behave as herbaceous perennials, dying back to the root in cold winters.
Pruning Butterfly Bush
Butterfly bushes must be pruned vigorously or their flowers will grow up so high that you can’ t see and enjoy them!
Since butterfly bush blooms on new wood, even if there is no die-back, cut them back to the ground early each spring. Yes, hack to the ground!
Also prune out dead stems, cutting them close to the ground.
Even where winters are mild enough for the stems to survive, prune severely to stimulate abundant growth on which flowers are borne.
We are no longer recommending new plantings of the butterfly bush, given its categorization as an invasive in most of North America. Instead, we recommend using plants that better support the native landscape and food web, given our declining pollinator population. See alternative plants that attract butterflies.
Here are a few great flowering alternatives that also serve as host plants for caterpillars: