Heart of the Garden

Never add raw, un-composted used coffee grounds to your soil.

Coffee grounds are so acidic, even acid-loving blueberries and azaleas wouldn’t appreciate sitting in a pile of your Maxwell House. If you add them to your compost, they should take up no more than 10% by volume. The same goes for the worm bin. You shouldn’t add more than 10% coffee grounds to your bin or it will become too acid for the vermies who like their bedding to have a neutral PH of 7.

A good way to neutralize a worm bin that may be too acid is to add egg shells.