Wow! Endless Summer Hydrangeas

Here is why I focus on flowers more that veggies in my garden. This year my faithful hydreangeas by my front door are getting more faithful care and nourishment.   I trotted out to the garden center and bought 8  two pound bags of aluminum sulphate, the silver bullet for achieving maximum blue blossoms.  I think it worked beautifully.  I apply the granules very liberally around the roots and water it in.   Caution, though. I did put too much on a miniature variety of Endless Summer and killed it.  That's a first for me. 
In the alkaline soil of Dallas, aluminum sulphate has to be applied several times throughout the growing season but it's worth.
What are your experiences with hydrangeas?