In my opinion the coffee grounds are good on most any plant.

Worms seem to love them! Maybe they get addicted to caffeine like humans do...

I've heard of coffee grounds on blueberries to increase soil acidity, but never on grapes, though, like Derek and bamboo said, worms love them and they are good for composting in general so I dont think it could hurt.

There is not a whole lot of acidic punch left in grounds, most of that is extracted. A lot really depends on the extraction method as well. Drip grounds will have more native acidity in them than say grinds from a good espresso machine. In both cases though I would not even consider the acidity as being an issue unless you were going to use grounds as a large portion of the soil mix.

Coffee grounds improve the soil just like any organic matter does. You face the same risk that you face by placing any uncomposted organic matter near your plants, i.e. heat generated by decomposition and temporary reduction of nutrients avalable to the plants during decomposition. Sometimes the grounds will also support the grouth of fungus and appear unsightly. Personally, I put all vegetable/friut remains and coffee grounds directly on my garden/raised bed soil and till it under in the winter along with composted leaves.

All coffee grounds are composted at my place. Nothing is taken from kitchen to garden beds directly, except occasional rinse water.

Ok here is a stupid question...

I've been putting used coffee grinds in a can to save for my grape and blueberry plants. I usually go out and pour the grinds out every few days. My current can of used grinds started growing a little mold. Should I throw them out or are they still ok to use?

Told ya it was a stupid question.

They are fine to use:) No worries.

"They are fine to use:) No worries."

Once you get used to the taste it's not bad! :)

lol