Hydrangea paniculata. Probably the most sun tolerant of all hydrangeas; can easily handle full sun in the northeast. The blooms are usually white and turn a shade of pink; then you get some greens and other pinks before they brown out. There are many varieties, some compact and others as tall as small trees. If you want to further identify it, get leaf and bloom close ups and post in the Hydrangea Forum. Or get a hydrangea book written by Dr. Dirr.

It develops invisible flower buds around late Spring to early Summer. The buds then open around mid Summer to early Fall (earlier in the South). Can be pruned down heavily although it is usually recommended to prune stems in 3 years... First prune the 1/3 longest in year 1. Then the 2/3 longest in year 2. And the rest in year 3.

You could start this rejuvenation pruning when the leaves fall in the Fall (so you can easily see inside the shrub) and when the plant has gone dormant (less stress on the plant).

Just a fyi... some versions of Miracle Gro have a lot of nitrogen and frequent applications raise the nitrogen levels high enough where they can interfere with blooming. Feel free to let it feed off the decomposing mulch thru the whole year or give it a layer of organic compost/composted manure or some cottonseed meal. A single application will do for the whole year since these guys do not eat fertilizer like roses do.