When is the best time to prune back my butterfly bush? I would like to concentrate the growth a bit lower, as the upper branches were on my roof (it is planted outside a one-story part of the house). I understand about directional pruning, I just didn’t know when, as new growth is now sprouting.
The Gardener’s Answer
Butterfly bush (Buddleia davidii) is a wonderful addition to any sun-loving garden, especially if your goal is to attract wildlife. Hence the name, these plants are certain to attract butterflies and even hummingbirds.
The best time to prune these flowering shrubs is late winter or early spring while they are resting and before they put on new growth. Since yours is already putting on new growth, be careful as you prune not to damage the tender new growth.
As a general rule we prune spring-flowering shrubs after they have finished blooming. This includes all plants that flower before June 1. For the summer-flowering shrubs, those that bloom after June 1, they should be pruned during the winter months or in the early spring before new growth begins. Pruning our plants rejuvenates them, encouraging new growth and larger flowers.
Butterfly bush blooms on new wood (current season’s growth) so they can be pruned back hard. Ideally, you want to cut it back to around 12 inches annually. This seems drastic but Buddleia are tough plants that respond well to hard pruning. They are woody near the base of the plant but produce new herbaceous growth year after year.
When you prune, make certain that your tools are clean and sharp. Feel free to thin out the plant to improve air circulation. This summer as your plant blooms and the flowers fade it is a good idea to remove the spent flowers. This will promote continuous blooms throughout the season and into the fall.