When do I cut back my butterfly bush?
The Gardener’s Answer
Hello, Wilma: 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 sub-shrubs is late winter or early spring while they are resting and before they put on new growth. Pruning our plants encourages them to put on new growth, so doing this in the late summer or fall will make any new tender growth very susceptible to frost damage. Butterfly bushes bloom on new wood (current season’s growth) so they can be pruned back hard, but avoid removing any woody growth. Ideally you want to cut it back to around 12 inches. This will encourage larger flowers as opposed to not pruning at all. Butterfly bushes are woody near the base of the plant but produce new herbaceous growth year after year, which is why they are classified as a sub-shrub. When it is time to prune, make certain that your tools are clean and sharp. For now make sure that your butterfly bush has no more than a couple inches of mulch around the base of the plant to protect the roots from the upcoming winter weather. Next summer as your plant blooms and the flowers fade, it is a good idea to remove the spent flowers. This will promote the plant to continue blooming throughout the season and into the fall.