Something free for your garden from Starbucks. Their Grounds For Your Garden program offers up free, used coffee grounds for your use in the garden. Just contact your corner Starbucks to learn more. The grounds can be of use directly in your garden or in your compost bin... Applying coffee grounds directly in the garden: Coffee grounds can be applied along with other materials as a side dressing for vegetables, roses, and other plants. Coffee grounds are high in nitrogen, but are also acidic. Adding brown material such as leaves and dried grass to the mulch will help keep a balanced soil pH. Mixing coffee grounds in your compost: Coffee grounds act as a green material with a carbon-nitrogen (C-N) ratio of 20-1. They make an excellent addition to your compost. Combined with browns such as leaves and straw, coffee grounds generate heat and will speed up the composting process.