I incorporate coffee grounds into my potting media, which I custom-make in a large wheelbarrow. I go through approximately 10 cf. of this mix each year. The "backbone" of my mix is always milled sphagnum moss. I use liberal amounts of "chunky" perlite as well. I really don't worry about all the "science" of whether the grounds produce nitrogen quickly or whether that nitrogen is "available". I could not care less. I just don't waste the coffee grounds. During the spring and summer, I toss a handful of grounds onto each of my azaleas and my groupings of gingers/cannas. I have done this for many years. Does it do any good? I don't know. Does it do any harm? Hardly.
