if it roots that easily ... grow it in a pot.. when it starts to get too big.. root some more.. and then throw the monster away .... it should already be in soil ... perhaps in a tent ... water roots are nto the same as soil roots... so plant it quickly ... if the plant it too tall for a baggie ... make more cuttings... and start more.. to give to friends... until it is small enough to fit into a plastic bag for tenting ... i doubt you will find a way to kill it.. short of no water .... ken

Hydrangeas are considered 'caning' shrubs and they do produce new stem growth from the root crown. That's one of the supposed big advantages of selections like Endless Summer - even if they die back to the ground with winter cold, they will resprout from the base. It is also the concept behind rejuvenating old or very overgrown hydrangeas - removing upto 1/3 of the oldest canes each year at the base encourages the development of fresh, vigorous basal shoots. Older growth can indeed be 'spent' or fail to bud, whether due to old age or to cold damage - this is called dead wood. If there are no signs of budding (what you see now are only leaf buds) along these stems and the wood looks gray and dull, these can and should be removed back as far as you can. You can always check to see if the stem is still viable by scraping the bark. If it shows signs of moist, green tissue under the bark, it is still alive. If it looks dry and woody, it is dead and should be pruned out. When in doubt, the pruning of bigleaf hydrangeas can always be limited to the three D's - damaged, dead or diseased wood.

Hamburg is a Great suggestion! RF Felton looks possible too, but it's flowers in photos are held higher on stems not so close to bush. We do have acid soil and I added aluminum sulfate a few years ago.

Looks like a just a regular old clump of blue phlox, which bloom this time of year. The are not a shrub, just a medium size perennial flower that can spread slowly over the years. See this picture as an example: http://www.pocketpoems.info/resources/blue%20phlox2.jpg