They will grow and flower best when planted in full sun or part sun and shade. Be sure to plant them in a spot where the soil is well drained. All deciduous shrubs like the 'Butterfly Bush' are best transplanted during the winter dormant season months of November through February. However, container grown plants can be planted at any time. In fact, I purchased another one just a couple of weeks ago.
Planting is really very basic.
Simply prepare a large planting hole, about twice as large as the root ball of the plant you are planting. Set the plant at the same depth as it was previously planted. Then mulch lightly with bark or sawdust. These plants are not heavy feeders. In fact, the plant I have has not been fertilized since planting a couple of years ago.