Keep them healthy and tidy with a timely trim.
In June and early July summer flowering shrubs such as the lovely scented philadelphus and floriferous kolkwitzia, deutzia and weigela make a great show in the garden. If not pruned, after several years all of these shrubs can get too tall or wide and take up too much room in the border.
To keep the shrubs to a manageable size, healthy and flowering, a little annual pruning should be done after the blooms have subsided. With shrubs that are only a few years old, light pruning is done to create a bushy shape, but once the shrubs are four or five years old pruning is needed to control growth and also encourage flowers for the following summer.
The aim is to create a natural shape and keep the individual habit of the shrub being pruned. Philadelphus (mock orange blossom) tends to have an upright habit, whereas kolkwitzia (beauty bush), is rounded and more spreading. The general rule when pruning is to cut out as much of the old wood that has flowered and reduce the size by around one third. This is best done by cutting out flowered stems back to a side shoot, rather than trimming the bush all over.
Where shrubs are crowded and overgrown, you may need to prune heavier by taking out some old stems at ground level to encourage new growth.