pruning advice on lavatera

For really hard pruning, early spring is the best time, once the threat of hard frosts has passed. You can be really ruthless with it, taking it down to something like twelve inch stumps. In the meantime, you could reduce it by about a third now to prevent winter storms smashing it to pieces

Having planted a number of Lavatera Tree Mallows I now realise that they are larger than I thought, can I move them if so when is the best time and how would I do this?