NB blooms on old wood so prune next year in order not to loose Spring 2010's blooms. You can prune any time after the plant blooms but before the start of July.

I'd consider relocating them to where they have sufficient room to grow without obstruction or the need for pruning. Nikko's are big shrubs and the need for regular pruning to keep them to a specified smaller size inevitably jeopardizes the flowering potential, especially in areas like GA with a very long bloom season. Find a smaller scale hydrangea for the front - you are certainly not limited by selection in your area :-)

Thanks for your help. It will be hard for me to prune in mid summer as they bloom all summer. I have old blooms on them now. I love them when they turn that greenish color. Thanks. Sarah