There are several fine species and varieties (cultivars) of Deutzia. They all have the same pruning requirement as they flower on wood growths made in the previous growing season (Last year). This is important to realise, for the current year's growth - such as in late spring or early summer does NOT bear flowers. When to prune Deutzia is essential knowledge for succession of flowers.
Deutzias can get a bit unkempt in habit if not pruned regularly. Prune at the right time!