Growing Butterfly Bush
Posted On April 1, 2020
The butterfly bush (Buddleia davidii) is a beautiful, fast-growing, deciduous shrub with masses of blossoms long, spiked trusses that bloom from summer to autumn.
Its flowers come in many colors, though butterflies seem to prefer the lavender-pink (mauve) of the species to the white and dark purple cultivars.
Also called “summer lilacs,” butterfly bushes are hardy to Zone 5 and remain evergreen from Zone 8 south. The shrub is low-maintenance, only requiring dead-heading and annual pruning in later winter to encourage flowers and a compact shape.
Please note that the butterfly bush, originally imported from China, has been classified as an invasive species in most U.S. regions. In other words, the butterfly bush is known to crowd out native plants that are essential to wildlife, including butterflies and birds. In warm climates, it can become a noxious weed and spread aggressively, while in cooler climates, it mostly stays contained within a garden’s cultivated soil if gardeners deadhead the flowers.
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.
How to plant butterfly bushes
- Buddleias need full sun and fertile, well-drained soil.
- Plant in spring or fall before frost.
- Loosen the soil, mix in compost, and 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
- Space plants 5 to 10 feet apart, depending on the variety.
- Water thoroughly.
How to care 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 and 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.
- Since they bloom on new wood, even if there is no die-back, cut them back to the ground every spring. Yes, hack 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.
- Susceptible to capsid bug, caterpillars, weevils, mullein moth, and spider mites.
- Fungal leaf spots and die-backs can occur.
- Butterfly bushes are one of many deer-resistant plants.
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.