I inherited this hydrangea from a previous owner, 5 years ago.

It's approximately 7 feet tall and at least as wide.

First of all.... what is it? I assume a paniculata?

Last year, while pruning, I ended up mistakenly taking out an important section from the middle of the shrub. So, trying to "go with it" I pruned it to look a bit more horizontal. I maybe took out 1/4 of the total growth.

This year, I've not done anything to shape this hydrangea and now it's HUGE! I'm sure that's due in large part to pruning it so severely last year. At this point, I really want to prune it back to about 4' tall and wide... and possibly down to just the main 4-5 'trunks'.

What impact would this have on it next year? Will it stunt it or will it do like it did this year and just send out a ton of new growth?

Thanks,

Melissa

PS...Sorry about the pic sizes. I usually do not have a problem with this kinda thing.