Southernwood Trimming

I purchased a plug tray of Southernwood a couple of years ago from Richters. It presently has made a fine feathery hedge. I am in the process of moving parts of it and need to know if it can be trimmed. The bottom has become quite leggy and it would look better in the new location if it were shorter and bushier. I do not want to loose any so need to know when and if it can be trimmed.

The safest time to trim it is in early spring just as the plant is breaking into new growth. The worst time is the fall as the plant is trying to get ready to survive the winter. Trimming it then may force it into late growth, which would not leave it enough time to harden before the winter and the whole plant would die. Transplanting should also be done in early spring. Spring is the only planting time after which I have been successful in overwintering the plant out-of-doors in zone 4.