When can I transplant azaleas, spireas and boxwoods?
The best time to transplant a Boxwood is in the fall.
Late Winter or early Spring is best to move a Spirea.
If you live in a cold climate, Spring is best for the Azalea.
Warmer climates you can transplant an Azalae late summer to Fall, avoid the hottest part of the Summer.
Here are some articles with more information.