I used to use grounds in my mini garden when I was a kid, and I remember that strawberries and dianthus seemed to love it. I still dump grounds in my yard when I remember, with no adverse effects.

~I would check this page for really great info:
http://www.sustainableenterprises.com/Business/coffeefert.htm

~As for the exact science as far as what's happening using grounds, I'm not cognizant, but you can check an old cached copy of a discussion from the Roses forum: (I attached link to this msg, it's kind of long.)

~for more reading, go to Google and enter a search for:
"Coffee grounds" garden. You can also add the word "science" to drill it down more.

~you also might ck with your local Cooperative Ag Extension if that's available in your area:
http://www.csrees.usda.gov/Extension/index.html

~Here's another interesting use for used coffee grounds!
http://news.nationalgeographic.com/news/2004/10/1025_041025_java_log.html

Have fun !

Here is a link that might be useful: Roses Forum old msgs re coffee grounds