Coffee Revs Up Your Morning and Your Compost Pile

Stopping by the Master Gardener compost pile I noticed a large plastic bag which turned out to be full of coffee grounds. Why are these here? This prompted me to see what’s up with coffee grounds and compost.

Composting is the process where natural materials are broken down by microorganisms to form a nutrient rich, soil-like material call humus or compost. Compost uses two different materials:  Green matter, such as vegetable scraps, grass clippings and, yes, coffee grounds, and brown matter like dead leaves, straw, shredded paper and non-diseased plants. Composting is an easy way to reduce waste and create a valuable gardening supply.

Coffee grounds are the granules that are left after brewing coffee. These are considered green matter in the compost pile. Checking Penn State Extension sources as well as Extension Services in other states revealed that coffee grounds are a good addition to compost as part of the green matter. They can be added to vermicomposting or worm composting. This is a natural method using worms to help compost food and organic scraps. It can be done year-round, indoors and outdoors.

What’s in Coffee Grounds?

The Brooklyn Feed Website reports “Starbucks commissioned a study in 1995 to better understand the make-up of the organic matter we call coffee grounds.” See the chart for the information provided.

In addition to adding your daily grounds and filter you can get coffee grounds from Starbucks here in Chambersburg. They certainly have plenty and as part of Starbucks recycling/reuse mission they provide them free of charge. If they aren’t outside at the back of the store, wait your turn and ask a barista if any are available.

Applying coffee grinds directly to your garden: Coffee grounds can be applied directly as a top dressing/mulch to acid loving plants like blueberries, hydrangeas, and azaleas. Adding brown material such as leaves and dried grass to the mulch will help keep a balanced soil pH.

More information about composting for the home garden is available at:
Penn State: “Lasagna” Gardening – Composting in Layers
Penn State Extension: Starting Composting
Oregon State Extension: Coffee Grounds and Gardening