Perk Your Garden Up: Using Coffee Grounds in the Garden

Every day in America, millions of pots of coffee are brewed at homes, restaurants and coffee houses. That means that millions of pounds of used coffee grounds, filters and bags are ending up in garbage cans, instead of being reused or recycled. That is a tremendous waste, as coffee grounds are a rich source of many nutrients, and make a fantastic (and free) garden fertilizer.

What is so great about coffee grounds?
Coffee grounds are loaded with nutrients any garden would welcome. They are acidic, and will balance out any alkalinity problems your soil may have, as well as adding texture to your soil. They contain 2% nitrogen fertilizer, as well as magnesium, calcium, phosphorous, potassium and trace minerals, making it a perfect fertilizer. Worms love coffee grounds, and wherever you find worms, you’ll find good soil. Using coffee grounds in your garden will attract worms, and the worms will aerate your soil, making drainage better, and loosening compacted soil so that plants and trees have an easier time building root systems. Ants, slugs and snails hate coffee grounds, so adding them to your garden will discourage them from feasting on your plants. Mulching tomato plants with coffee grounds gives them an extra nitrogen source, and may prevent blight. Not to mention, they just plain smell good! Walking around in a garden that has been mulched with coffee grounds smells fresh and earthy.

How to use coffee grounds in the garden
Spread coffee grounds 1 to 2 inches deep as a mulch layer under acid-loving shrubs such rhododendrons, evergreens, and blueberries. Roses also appreciate a coffee ground mulching. Apply in a thin layer to allow good water penetration and to prevent too much mold from growing on the grounds. Don’t worry about a slight layer of mold. When potting or planting new greenery, coffee grounds can be mixed in with the potting soil to give it a boost, making sure not to add to more than 25% of the total soil volume. For a liquid fertilizer ‘tea’, coffee grounds can be diluted by soaking in a bucket of water. This solution can be used to apply directly to your outdoor plants as well as indoor plants. Before planting your vegetable garden, work an inch or two of coffee grounds into the soil, making sure to dig it down to a depth of at least 3 inches.

When using coffee grounds in the garden, be sure to remove the paper filters, as they aren’t particularly attractive. These filters can be worked into any composting pile, and will break down rapidly. If you are using smaller amounts from your own coffee drinking, these grounds can be saved in an empty coffee can with a lid under the sink, until you have the desired amount, or they can be sprinkled randomly in small amounts all over your garden.

Create an attractive pathway with coffee grounds. Coffee grounds make an attractive and nice-smelling weed-barrier, and so are perfect for creating walkways or for filling in between stones or bricks.

To discourage pests like ants, snails and slugs, sprinkle a barrier of coffee grounds around the base of any plants you are trying to protect, as well as in any areas with noticeable pest activity. Sprinkle the grounds near anthills and in moist areas pest like to frequent. Coffee grounds are both acidic and abrasive, so a barrier of grounds placed near slug-prone plants such as hostas, ligularias, lilies, daffodils and other spring bulbs may protect them from these garden pests.

Coffee grounds can also be added to compost piles, as well as the paper filters and paper bags. They will help the compost break down faster. Just toss the filters in and give the compost pile a turn.

Worms love coffee grounds! Add some to your worm bin every week or so, a cup of grounds per bin per week. Don’t add too much at once, because the acidity could bother your worms.

Where can I get coffee grounds?
The benefits of using coffee grounds in gardens have been recognized by many. Starbucks offers free bags of used coffee grounds in many of their cafes. Some offer large bags that still have the coffee filters in them, but others offer bags of ‘Grounds for Gardens’ that are filled with fine-ground espresso without the filters. Call your local Starbucks to find out when the bags are available, as sometimes they do run out if a lot of people are picking them up.

If you do not have a local Starbucks, almost any local coffee shop will agree to save their used grounds and filters, provided that you give them a special bucket to save them in, and pick them up regularly. Alternately, you can save up coffee grounds from home and from your work or office. Providing a bin with a sealable lid will encourage your coworkers to put used coffee grounds and filters there.

Whether you pick up large bags of coffee grounds from a coffee house, or just use the grounds from your daily pot of coffee, reusing them in your garden is beneficial to your plants, while at the same time diverting a useful product from ending up in a landfill.