When I stop in at my local Starbucks for my daily "fix", I always check for the bags of coffee grounds to use in my garden. Why do so many people want these grounds? Let me tell you what I know about the benefits of coffee grounds in the garden.
The benefits of using grounds are many. They provide an almost neutral pH, add nitrogen to the soil, and can improve soil drainage and help the water-holding capacity. Paper filters can also be composted.
HOW TO USE COFFEE GROUNDS IN THE GARDEN
Scatter the grounds around the drip line of your trees, shrubs and plants. This provides a gentle leaching of nutrients to the plants.
Rev up your compost pile with coffee grounds. They decompose quickly, get hot and help decompose larger matter like wood chips and pruning material. You want to mix 1 part coffee to 2 parts grass clippings, leaves or small wood chips. You can increase the grounds late in the season to really heat up and speed up the composting effort. Make sure to really mix the grounds into the compost pile.
Dump about 1/2 pound of grounds into a 5 gallon bucket of water. Let it brew overnight. Use this liquid fertilizer in the early morning when the air is cool and calm.
Some people have said that coffee grounds deter slugs and other pests but I can't say whether that is true or not, but worth an experiment, maybe.
When I re-pot plants, I add about 10% coffee grounds to the mix of potting soil. Mix thoroughly before adding it to the pot.
Enjoy your java and reap the garden benefits. What a win-win effort!