How to Prune a Smokebush

Local nicknames sometimes describe plants accurately but confuse their identity from one place to another. Depending on location, an increasingly well-known variety of butterfly bush, Buddleja madagascariensis, may be called smoketree, golden butterfly bush, orange buddleia or smokebush. Like other buddlejas, smokebush grows best in your landscape when correctly pruned. Three types of pruning strategy help maintain smokebush as part of your landscape.

Hand or power pruners

Small rake

Drop cloth or drag bag

Compost heap or other disposal area

Bleach or alcohol

Prune smokebush that grows outside as a perennial shrub late in the winter, to encourage formation of new flower shoots before spring/summer blooming. Do a drastic pruning, which means cutting all stems of the shrub to within 6 inches of the ground. Smokebush is a naturalized tropical plant fully hardy in United States Department of Agriculture plant hardiness zones 9 and 10. With shelter, it can flourish in warm zone 8 gardens, but you should expect dieback at 18 degrees F or below.

Where dieback is not an issue, do a drastic pruning late in winter, cutting any old dead, broken or tangled branches to ground level as well. This will help shape your shrub. Buddleja madagascariensis tends toward sprawling growth and can get out of control if old branches are not cleaned out. To prevent the spread of any possible disease and to keep cut branches from sprouting where not wanted, rake all refuse away from the plant and dispose of it in your compost heap or brush pile. Clean your pruning shears with alcohol or a solution of 1 part bleach and 9 parts water prior to cutting to discourage the spread of pathogens.

As the first flower heads begin to dry and discolor, cut flower-sprout branches back to a pair of leaves at least 6 inches below the bloom. Flowers bloom on new wood, and, although second-flight flowers tend to be smaller and less frequent than the first blooming, you can keep some color going on your shrub through most of the growing season. Each flower stalk you cut has the potential to sprout several branches and several new small flowers.

Buddleja madagascariensis is a tough plant with a tolerance for poor soil. If you decide on periodic pruning to increase blooms throughout the season, resist the impulse to add unnecessary fertilizer.

If you grow smokebush as a conservatory or greenhouse plant, prune it back to the desired shape as soon as flowering is finished in late spring.

Do not confuse Buddleja madagascariensis, smokebush, with Cotinus coggygria, smoke tree, a similar-looking family member that can grow in USDA hardiness zones 5b through 8.

Buddleja madagascariensis has achieved invasive status in Hawaii, and environmentalists elsewhere note its aggressive growth in other parts of zones 9 and 10. Especially if you are considering it as a filler plant for a large area, check with local environmental authorities for current concerns about uncontrolled spread.