pruning

Hi,i have two pieris (forest flame /flaming silver) planted in large pots in ericaceous compost,but are now large and want to prune them,how and when do i achieve this.Up here in the north east everything is growing fantastic exept cucumbers,first two got frosted in cold greenhouse second lot have just keeled over after waiting three weeks(yesterday)

The most natural-looking way is to take out about a third of the branches back to the base every year - they will produce new low shoots, and over three years you'll get a bushier and shorter plant.

Thank you very much will do.

Forgot to mention, after flowering up to now is a good time to prune.

Once the rain stops i,ll be out there thanks.