I can't really say it has helped much but I did get a bloom on my hibiscus so maybe... I get coffee grounds from a local cafe and dump a couple inches across the bed that the hibiscus is in. It makes it nice to water or when it rains, I can smell coffee
Oh, I've got horribly high PH as well, sitting on a pure limestone rock down here. I swear even the rain is high PH, I'd like a little acid rain.