This plant tends to spread through suckering, so these ground suckers will need to be trimmed off if you want to keep the shrubs confined. If desired, the shrubs can be pruned for shape or size immediately after the spring flowering period. A good pruning routine is to remove all dead wood, as well as some of the oldest stems all the way to ground level. This will open up the center of the shrub to sunlight, which will reinvigorate the shrub. Tips of branches can also be trimmed to control the size of the shrub.