Not to drink of course. But we’re always looking for ways to minimize our environmental impact while improving our lives, and the coffee project came about in an odd way. I try to maintain a healthy lawn that’s weed-free and doesn’t require a lot of water to look good. The fewer chemicals I have to put on it, the better. So in doing some research about an ant infestation, I was surprised to find out that used coffee grounds are especially effective at repelling and killing ants. Further reading revealed that the used coffee grounds make an excellent additive to compost, a soil amendment, and even fertilizer. And thus the coffee project was hatched. First the why, then the how.
As compost, used coffee makes an excellent green additive, because it’s rich in nitrogen. A common misconception is that it’s also high in acid, but this has been repeatedly proven to be incorrect, with the actual pH being close to neutral. After brewing, the beans lose their acidity. So you can mix the grounds into your compost pile, as long as they don’t make up more than about 25% of the total volume. An added benefit for composting is that the used grounds elevate the temperature of your compost, which keeps weeds at bay.
Amending your soil with used coffee grounds yields some excellent benefits as well. Take advantage of what worm farmers have known for years, and till some into your soil, creating an extremely friendly environment for worms. They’ll happily improve your soil in return. (I’m not sure if they work more effectively with coffee, but it’s been proven in people…) You can use it at up to 35% by volume, tilled to a depth of 6-8 inches. This also makes appreciable amounts of phosphorus and potassium available to your plants, whether that’s grass, flowers, or a vegetable garden.
Typical used grounds are just over 2% nitrogen, but it’s not readily available for plant use, since it has to be broken down first. The good news is that makes used grounds an ideal slow-release fertilizer for your lawn. Not only does it take care of the ant problem that’s plagued my yard for years, but as the coffee slowly breaks down, it will feed my lawn. And it’s not just a lawn fertilizer – since the used grounds repel slugs and snails, consider if for your garden as well. This is certainly preferable to traditional fertilizers that sometimes require gloves and a mask for safe handling.
While we’re improving our lawns and gardens, we’re also keeping this awesome organic matter out of landfills, which is just another bonus. With all those benefits, the only question remaining was how to get enough used coffee grounds to be effective. Sure, you can go to that coffee chain near your house and get a little bag that’s good for a window box. But it would take quite some time to collect enough for a lawn or garden. Then I read about a guy that drops off five gallon buckets at his local donut shop. They brew a ton of coffee (quite literally, when measured over time), and were happy to save the grounds for him. So I went to my local home improvement center and purchased a pair of buckets with lids for under $9. I dropped one off at the gas station near my work, since they serve quite a bit of coffee. I’ll check back every few days until we determine how quickly the bucket fills up, and then I’ll swap it for an empty. Once I can get some of my neighbors on board, we’ll collect from other local businesses that brew large amounts of coffee. Look for an update as things start to warm up.