This shrub, which flowers from June through to October, forms itself into a bushy clump in about two years. It can reach a height of between 2m and 3m depending on the region and the soil.
After planting, cut it back to just above two opposite buds, half way up the main branches. This will help it form the bushy shape. If necessary cut out any weak or dead branches. This will encourage several young vigorous shoots to appear and produce flowers. After flowering, which takes place between June and October cut off the dead flowers.
In the second year at the start of spring, around March cut the branches that come off the main boughs very short, to about 5 to 10cm in length. Always cut above a pair of opposite buds. Try to keep the shape balanced: cut back the vigorous branches at the top to a short length but leave those at the bottom longer so that all the branches are about the same height. After flowering cut off any dead flowers.
In the following years in March, prune in the same way as in the second year. After flowering cut off the dead flowers where possible. It is likely that the bushy shape will start to get too dense with lots of branches straddling one another. Cut out any weak or dead branches and ones that are growing inwards.