Q: I heard that coffee grounds are good to put in the compost, but someone else told me they are too acidic.
You heard partly right, but one of your sources is sadly behind the times.
Coffee grounds, along with paper coffee filters, are great as an ingredient with compost (including indoors “vermicomposting”). Bonus: coffee grounds, like tea leaves, are a good source of valuable natural nitrogen — the main ingredient that helps beneficial bacteria break down organic matter into finished compost.
In fact, a lot of savvy compost makers make it a point to be on good terms with neighborhood coffee shop baristas, who can provide buckets of spent coffee grounds and filters, and tea bags, for compost bins.
While it’s true that coffee grounds themselves are acidic, this has little long term effect on compost. The old advice of avoiding acidic materials, and even for adding agricultural lime to compost bins to decrease acidity, is based on a short-term phenomenon; as leaves and other organic materials slowly break down, they naturally release organic acids. But in the long run, most compost actually settles down to somewhat neutral, even without the additions of lime.
So use those coffee grounds, tea bags, eggshells and vegetable scraps! And don’t worry about the acidity.
Expert and certified wit Felder Rushing answers your questions and lays down some green-wisdom. You can get more of your Felder fix at www.slowgardening.net.