If you like the hygrandgea alot....try not cutting it at ALL this year and see what happens and if you live north where the tips may be getting die back,cover the plant with some burlap.
OR
try one of the newer ones like endless summer that will bloom on new AND old wood
The PH is what usually affects the color of the
flowers.I'd have to go test mine to see what it is,but I get soft lavendar blooms& then my nikko I make sure too Aluminuim sulphate it to keep the blueness.Too much nitrogen can make them not bloom& though they claim too much shade will do the same....my niko gets little sun if any,but does have few blooms(I did move a portion of it though...to more sun)I love the oak leaf ones.I'm in love with the fall coloring in the leaves.I live far enough south I don't get much fall coloring...my sugar maple just teases me..lol