Okay, since you ask.....I took a quick run around town, checking the hydrangeas.
We get a wide variance in coloring, from whites through the palest blues, purple (my favorites), cobalt blues, etc. I think if you're surround by the evergreens, your soil is acid and if your land has been open land for years, the soil is not as acid. My friend in Pistol River has a couple or so acres surrounded by woods...if I'm correctly remembering what she said about hers, she can't do the 'red' hydrangeas, friend barb, here in our area has 640 acres that has been open farmland for many years and her soil is not acid, she can do the 'reds'.
It remains to be seen what my hydrangeas will do without treament, right now I have the white Shooting Stars type, a couple of Paniculata hydrangeas, a couple of Oakleaf, some that are in the lavender to purple range...not really any that are in the large mophead type...may be some but I've yet to pay much attention. I will go up to her property sometime soon to take a lot of cuttings.
These are pics from this a.m. of various hydrangeas close by...