I can't give you a specific answer here but I do know that the color of some hyrangeas differ depending on the pH of the soil.. can't remember off the top of my head whether acidic soil makes them pink or blue... you'll have to look that up on google but I'm sure it'd be an easy fix to alter the pH of the soil around the plant... maybe. :-))

Sorry I couldn't be of more help!
ttfn
Cheryl.

Hydrangeas need acidic soil to turn blue (or dark purple). She can experiment with mulching them in pine needles or oak leaves. Otherwise there are acid additive granules available on the market. Just read the package directions carefully.

MeMo

alumninum sulfate easily available at hardware stores and garden centres. Just follow the instructions on the package. This will turn those hydrangea's blue.

and these types of hydrangeas are good for sun and or part sun - not full shade. Full shade (but not deep shade) hydrangeas for example are oakleaf hydrangea.