I was just reading in a gardening magazine last night that roses love coffee grounds! It says to actually plant them around the roots of the roses! Oh, and tea leaves too.
The reason you use them sparingly is that they are not a complete fertilizer, they are highest in nitrogen. I've heard that some people mix it with other organic inputs to make a more balanced ammendment.
There was a thread a while back about this topic. One neat thing is the grounds will discourage slugs if they are placed on top of the soil around plants.
I get coffee grounds from starbucks as well and while its tempting to get as much as you can because its free, it sounds like you have way too much, unless you have a enormous compost pile.
My neighbor brought home a trash can full of grounds from starbucks about 3 weeks ago. He amended it right into his soil, into the bed he was using for strawberries!!!
He says he goes back as often as he can in the spring and winter getting his soil ready. However, he does have a HUGE conpost pile and that gets mixed in too.
I drink about a pot a day, and I've been dumping my grounds into my compost pile rather then into the garden directly.... is that a good course of action?!
I usually just dump my coffee grounds in the compost. A good source of "green" material. I will collect them for a week or two and put some around the few roses I have occasionally. It seems to help keep the deer from snacking on them for a few weeks. Of course that could very well be wishfull thinking on my part.
Funny I just had a similar conversation with my neighbor and yes farming can be more of an intellectual pursuit than the average lay person would believe. It depends upon how in-depth and serious you are about any given subject -- take for instance "grass farming."