Cutting back

Philadelphus - cut out any dead bits and back by about one-third as soon as it's finished flowering, so that's probably July. You can also cut out a few branches from the base, if it needs to be 'opened up'.

Lavatera - cut the flowered stems back by about one third in the autumn, then cut it hard back in early spring. This avoids wind-rock in the winter, and the second prune is to stop the plant getting too big and woody.