A butterfly bush should have the seed heads removed before Spring due to re-seeding. However, do not remove any branches until the Spring. All dead perennials should be cut back 4 to 6 inches. Leave some growth on top to protect the roots from any hard winter freeze. Also, cut back any watersprouts on trees. Watersprouts are fast growing, vertical shoots that grow from healthy branches. They divert energy from a tree's overall growth.Here are a few plants that you should not prune in the winter:
Lavender or Butterfly Bush Branches
Ornamental Grasses
Evergreen or Semi-Evergreen Perennials
Roses
Hydrangeas
Also, leave some food for wild life over the winter months. Leave viburnum, cotoneaster, ilex and hawthorn fruits on the plants. Leaving the ornamental grasses provide some protective habitat for wildlife. Birds, insects and small animals will nestle in clusters of dead branches and debris through winter.
A great book to read for more information is The Pruning Book by Lee Reich. Click Here to read more about this informational book.

Plant brightly colored or fragrant flowers. Their pollen is large and because insects pollinate them, the pollen is seldom airborne. A good sign as to whether a plant is a good choice is if you see a lot of bees and butterflies around it.