When do you prune butterfly bushes so that they thrive and bloom from year to year? —Robin Hatinger, Lakeview, MI
Butterfly bush (Buddleia spp.) blooms on both new wood (new growth in spring) and old wood (branches that came through winter in good shape). Even if the plant freezes back to the ground, newly emerging canes will bloom that same summer. And their flower clusters are truly butterfly magnets.
Prune your butterfly bushes according to how large you want them. Left to their own devices, they grow 10 feet tall. Many gardeners, however, prune them back hard in early spring and shear vigorous new growth lightly before flower buds develop, about mid-June. Then shrubs are more compact and less rangy at bloom time and the rest of the growing season.