Coffee used as a fertilizer is not exactly a new idea. Many gardeners add coffee grounds to compost piles where it decomposes and mixes with other organic matter to create some fantastic nourishing soil. Of course, this is done with grounds, not the actual cold cup of coffee sitting here at my desk. So, can you water your plants with coffee proper?
Coffee grounds are about 2 percent nitrogen by volume, nitrogen being an important component for growing plants. Composting grounds introduces microorganisms that break down and release the nitrogen as it raises the temperature of the pile and aids in killing weed seeds and pathogens.
Very useful stuff! Brewed coffee also contains measurable amounts of magnesium and potassium, which are building blocks for plant growth as well. Therefore, it seems a logical conclusion that watering plants with coffee might indeed be very beneficial.
Make compost
Coffee grounds are rich in potassium, magnesium, phosporous and copper. Just toss fresh grounds in your planters and next to your plants in the garden. If you’re an avid gardener, ask for used grounds for free at your local coffee shop! Unless you’re adding inches of coffee grounds to your garden, you’re not going to see a difference in your soil pH. After making the morning wakeup, coffee grounds contain up to 2% nitrogen, similar to grass clippings.
Repel ants
Ants are extremely susceptible to caffeine. This safe material confuses the worker ants because they lose their scent trails. Leave coffee grounds where the ants are and they will carry it home and eat it. This method takes a few weeks to see, but after a while you’ll notice a decrease of the ants population.
Repel slugs
If you fear a massive invasions of slugs in your garden, cover the soil with used coffee grounds and create « olfactive barriers ». Your regular cup of joe contains about 0.05% caffeine, this means that coffee grounds and fresh coffee will not kill slugs but may act as a mild deterrent.
Feed earthworms in your garden
Worms are highly beneficial for the garden and they just love coffee grounds. So feed them generously, they will thank you!