A Nice Cuppa

Even though I typically just brew a single shot of espresso a day, I find myself with a lot of left over coffee grounds. Luckily, I also have a garden, and the grounds make a great addition to the soil (as does my other vegetable-based garbage). But, as I found myself digging my latest batch of grounds, well, into the ground, I got to wondering why I was doing it. Sure, I’d heard it was good for the soil… but why? And in what quantities? And what exactly are the benefits?

A little digging, and I found that the coffee grounds are a great source of nitrogen and act as a slow releasing fertilizer when dug directly into the soil. It’s a good idea to water (or dig them in just before a rain) to “activate” the nitrogen. Alternatively, you can pre-activate by diluting the grounds with water… you’ll be giving your plants a gentle boost to their nitrogen levels, encouraging growth.

The grounds also attract worms and act as a repellant for pests like ants and slugs. If you have a cut-worm or ant problem, you might try a ring of grounds around the area you want to protect… of course, you’ll have to repeat this after each rain or watering, as the grounds will break down and no longer be effective. Be sure to mix up the soil each time you do this to avoid developing a fungus on your topsoil.

The smell of coffee grounds is also supposed to deter stray cats from using your garden as their personal outdoor litter box.

Before adding too much to the soil though, you should test for the soils acidity. If you have alkaline soil, the grounds are recommended. If your soil is already acidic, it’s best to use the grounds with caution. Also, make sure you understand what type of soil is best for the plants you are growing. Most plants prefer slightly acidic soil… but your lettuce, nasturtiums and phlox won’t. If you have tomatoes and blueberries, feel free to load them up. They’ll appreciate the buzz.

Also, remember that your plants need more than nitrogen to thrive, so coffee grounds shouldn’t be your only fertilizer.

If you don’t brew at home, but still want the benefits, ask at your local cafe for their left over grounds. Starbucks and Peets bag them and give them away for free.