Using Coffee Grounds in the Garden

Learn how to give your plants a pick-me-up using leftover grounds from your morning brew.
Plants like this creeping fig can benefit from the minerals found in coffee grounds.

Using Coffee Grounds in the Garden

Plants, like this creeping fig, can benefit from the minerals found in coffee grounds

Plants, like this creeping fig, can benefit from the minerals found in coffee grounds

There’s nothing quite like a good cup of coffee in the morning before getting started out in the garden. It warms the body, energizes the disposition and brings the world into sharp focus. If you enjoy a daily cup o’ joe, your first stop for tending to the garden is at your fingertips. Coffee grounds usually find their way into the trash, but we have a much better use for that daily grind.

Coffee isn’t normally appreciated for its nutritional value, but the organic matter found in that coffee filter is a notable source of nitrogen, potassium, phosphorous, magnesium and copper and can be used to bolster the health of plants without investing in costly commercial soil amendments. Even the caffeine coffee lovers crave finds an extra purpose for the frugal gardener.

What can coffee grounds do for your garden?

Lower Soil pH

It’s always a good idea to add coffee grounds to compost, but mixing it directly into the soil can help balance alkaline soil or give a boost of acidity for plants that prefer a lower pH, like hydrangeas or rhododendrons. Brew up a weak coffee “tea” using spent grounds to water plants or add coffee grounds directly to the soil in planters. You can also give houseplants an easy fix by lining the bottom of pots with coffee filters full of used grounds.

Fertilize Plants

As coffee grounds break down, they release nutrition in the form of nitrogen, potassium, magnesium and other minerals into the soil. For plants that do well in acidic media, augment soil with coffee grounds to help them thrive.

Deter Pests

Caffeine is toxic to slugs and snails and they will avoid coffee grounds sprinkled on the soil surface around plants. Coffee grounds are also a good deterrent when fire ants are a problem. In 2008, the Charlotte-Douglas International Airport in Charlotte, NC began successfully using recycled coffee grounds to discourage fire ants around runway lights, recycling nearly 2,200 pounds of used coffee grounds a week.

Feed the Worms

Unlike slugs, earthworms love coffee grounds. Using grounds in garden soil or in worm composting bins not only helps enrich the soil, worm productivity skyrockets, aerating soil and improving drainage.

If you don’t indulge in a morning cup or get your java on the go, many coffee shops have grown accustomed to requests for leftover grounds. Some have even begun packaging their leftovers for easy pickup. Don’t be shy about asking, they’re probably used to it. When I dropped in to see my favorite barista this morning, I was the second person of the day to pick up used grounds. As she handed me the bag, she offered a bit of gardening advice: “Plants love this stuff. Go venti.”

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