Coffee grounds are a readily available source of organic material. Starbucks has a national program of packaging 5 lb. bags and offering them free to the public. Port City Java also said that if you provide a bucket, they will save them for the public.
The Grounds contain about 1.45% Nitrogen, are slightly acidic, and hold water in the soil. They can be used to top-dress acid loving plants like blueberries or as a slow release nitrogen source in your compost. The proper amount to be used depends on the condition of the soil and, more specifically, what you are growing in your garden. Mixing coffee grounds in your compost acts as a green material with a carbon-nitrogen (C-N) ratio of 20-1. They make an excellent addition to your compost. Combined with at least 75% browns such as leaves and straw, coffee grounds generate heat and will speed up the composting process. Anecdotal evidence suggests that worms are very attracted to them so you can feel free to use them in vermiposting (worm bin) situations if you desire. For more information about composting:compost.org (Composting Council of Canada) compostingcouncil.org (US Composting Council) mastercomposter.com
