What are the critical points to consider when transplanting a large perennial like a butterfly bush? These bushes have been in the ground for one year; how late in the year can I transplant them?
Butterfly bush (Buddleia davidii) is grown in Michigan as an herbaceous perennial, since many years we can expect our cold winters to kill back upper parts of the plant’s stem system. The good news is we can usually trust that new leaf buds will emerge low on the stems or from the root system, producing new main stems and flowering buds that will bloom in late summer.
Knowing that the butterfly bush is a marginally hardy plant in Michigan, it is wise to wait to cut back or transplant until spring. In fall after the leaves have fallen, the plant completes its annual cycle by relocating starches (energy that is produced by the leaves and moved down to the root system for storage), which will be used as energy to begin spring growth.
It is helpful to prepare your bushes for winter this fall by keeping them well-watered and supplying them with a slow-release, organic nitrogen fertilizer that will be available in the soil during spring when the roots need it the most.