Japanese Mountain Hydrangea has been introduced to the market litttle while ago. But never getting popular. I believe the best way of using these small leaf hydrangea is as a ground cover. Most of the mountain hydrangeas are small leaves and weak stems. So if you plant one plants to your garden for accent like a regular hydrangea, it doesn't work. But if you use #1 or #2 pot, 4 or 5 of them plant together works very well. It covers your shady ground or under the tree. If you change soil PH to change the flower color. Ph to acidic become blueish, Alcaline become pinkish. Also it depends on the variety for the reaction from PH.