Our two blueberry bushes have seemed fairly healthy, so we have never tested the soil but I figured the coffee grounds couldn't hurt. I searched online a bit and the consensus seemed to be that roughly a pound of used coffee grounds per bush was plenty, and unless they were already in highly acidic soil, the grounds would help but wouldn't change they pH levels enough to harm anything. So, for about two or three weeks, I saved the grounds from Keith's daily pot of coffee. When I had what seemed like roughly two pounds, I took it out to the blueberry bushes, pushed back the straw we had underneath them, and dumped the grounds on.
Then I simply pushed the straw back up around the bush. It was recommended not to work the grounds into the soil because the roots of blueberry bushes are shallow and would be damaged by working the soil. Rain and watering will allow the grounds to break down and release their acidic properties until the soil and down to the roots. Or so I've read. It would probably have been most beneficial to do this earlier in the spring as the bush started growing, but I guess better late than never. What I read said it can be done twice a year, so I plan on doing it again in the late summer or early fall.
Now we just have to wait a little longer for our blueberries to ripen up, and hopefully they won't taste like coffee. While I was out there, I had the pleasure of finding a few of these beauties ready in the strawberry patch...
Funny little story...after picking the strawberries yesterday and having juice all over his hands, Bert was running around inside and came to me in the kitchen and told me he had stepped on a strawberry. I looked down and his big toe was bleeding. I still haven't figured out what he did, but it must not have hurt and he just assumed the blood was strawberry juice and kept insisting that he had stepped on one when I asked him what happened.