The benefits of coffee
Coffee, in any form, contains N-P-K (nitrogen, phosphorous, potassium), trace minerals and properties that help stimulate the growth of beneficial microbes. The best part of this story is that coffee grounds are basically free. Just ask your local restaurants or coffee shops to put them in a container provided by you. At the least, save and use your own coffee grounds at home like we do every day. Regular coffee is best, but decaf works almost as well.
Coffee grounds in storage tend to develop a green or blue-green fungus that looks like mold. Don’t worry, that’s good. The green fungus, a Trichoderma species, is really beneficial, while the blue-green one is reported to be only moderately beneficial. In any case, moldy coffee is helpful to use directly in the garden, in the compost pile and on interior potted plants. Diluted coffee is also an excellent organic fertilizer — especially for orchids and African violets — and may have some of the same pest control powers.