There was one grand old blue Hydrangea here when I moved to this house. I've made numerous propagations from it, given some away, put half a dozen or so in the ground in various places. Some are making mostly blue flowers, but some are pink, within a few feet of each other in one instance. PH is a fickle, mysterious entity!
Although I've had success with cuttings, that's a real PITA compared to layering. If you have an existing shrub, or permission to play with someone's, just bend a branch to the ground and put a rock or brick on it. Not all will do that w/o breaking, but it's usually easy to find a few that will. (Brush aside mulch, remove some grass, whatever is necessary so the branch will make contact with the soil.) No attention needed until it's ready, which would be when all 3 occur simultaneously; it has roots, you have time to dig (and nurture it in the near future if necessary,) you have somewhere to put it.
Another option is to bend a branch to the surface of a pot of soil if you can't find any to bend all the way to the ground. Maybe little more funky on the eyes for a short while, but definitely a viable option, and possibly easier for anyone who has trouble digging, bending all the way down. At least you only have to dig once that way, (the hole for it's new, permanent home.)
