Hydrangea leaves turning deep purple at edges
I'm not even sure if this is the best resource for this, but I'll give it a shot ;)
I just moved into a new home outside of Boston, and with it came a hydrangea plant (variety unknown). I haven't had to take care of anything more complicated than potted African violets before, so I'm not sure what's best for it beside watering, which I do regularly. The plant gets 6+ hours of sun per day.
Recently, many of the leaves (which were green) have taken a purple-brown tinge to their edges. What could cause this? I've read about everything from leaf scorching to phosphorous deficiency, but nothing seems to be shriveling or falling off (yet).