You can cut back some of the topgrowth in October, and then hard prune back down to within 2 inches of old wood in April.

That is great info for me too...thanks Bamboo....

Just a small addition to Bamboo's good advice - if you don't cut it back before the winter, the top growth can be severely damaged by wind or snow...these shrubs can split right open- bye-bye Lavatera!

This helps me also. Thank you