I usually feed most plants in the spring -- if you feed too late you get soft growth which doesn't survive the winter

I have never found it necessary to feed a Pieris.

I never feed Pieris either - unless they're in a pot, when I apply a handful or two of Growmore in early April, stir it in and top off with fresh compost.

I was only thinking of garden plants, Bamboo. Potted ones might appreciate a small feed.

thank you very much anb