Coffee Grounds For Plants: Don’t Waste A Precious Resource
Did you know that those spent coffee grounds in your coffee filter are the key to a happier, healthier garden? Coffee grounds can improve the health of your garden’s soil, serve as a natural pest repellent, and reduce the amount of waste that goes into landfills.
Keep reading to discover why adding coffee grounds to soil is beneficial and how to use this natural resource in your garden.
Why Are Coffee Grounds Good For Plants?
We all love the aroma and taste of delicious coffee beans, but aside from being a great source of antioxidants and energy, there are many other uses of coffee around your home and garden.
The freshest ground coffee beans help plants thrive by providing a rich nitrogen source. Coffee as compost material enriches your soil with additional compounds, like potassium, iron, calcium, and phosphorus. Coffee grounds can also inhibit the growth of weeds that rob your plants of essential nutrients and nitrogen.
The caffeine in the present coffee grounds is an excellent pest repellent but very attractive to the earthworms that break down organic material, making it a valuable addition to your raised garden beds or compost bins.
How To Use Coffee Grounds As Fertiliser
Most plants thrive in soil that ranges in acidity between 4.5 and 6.5 on the pH scale, when the nutrients in the soil are most available (1). What’s more, the soil’s pH determines the health of the microorganisms that break down organic material to produce the nutrients that plants need to grow.
Too low a pH level can render the plant nutrient manganese available at toxic levels…At a high pH level, the plant nutrient molybdenum becomes available in toxic amounts.
Plants like carrots, azaleas, blueberries, cranberries, lilies, cabbages, gooseberries, and hydrangeas thrive in soil within this range (2). Coffee is acidic, so if your plants thrive in acidic soil, it’s safe to incorporate coffee grounds as a foliar feed, fertiliser, or mixed with your compost and mulch.
Using Coffee Grounds in The Garden
Some plants — like tomatoes, alfalfa, lavender, orchids, and rosemary — thrive in more alkaline soil. While you can still incorporate some coffee grounds into the soil surrounding these plants, adding coffee grounds sparingly is a good idea until you know how your plants will react.
Closely monitor the leaves, stems, and veins for any signs of iron deficiency or toxicity.
These signs include the yellowing or death of leaves and stems.
How To Use Coffee Grounds In The Garden Safely
Coffee grounds raise the pH of the soil, which helps some plants absorb more nutrients. But too much coffee in the garden can harm household pets, earthworms, and other microorganisms that maintain the nutrient balance in your garden.
Ensure your compost has a healthy balance of green and brown material to avoid this. Green material, like coffee grounds, provides nutrients, while brown material, like dry leaves, enriches the soil with carbon (3).
Avoid mixing coffee grounds directly into the soil. As coffee grounds absorb moisture, they create a puck and prevent the free drainage of water through the soil. It’s better to sprinkle a small amount of coffee grounds around your plants.
Check out this video from Next Level Gardening for more coffee grounds dos and don’ts.
Used coffee grounds for plants are a great addition to your garden. They enrich the soil with nitrogen, repel pests, feed earthworms, and make nutrients more available. Not to mention, it’s a sustainable way to dispose of your coffee waste. A true win-win-win for you, your garden, and the planet!
No, you can not put coffee grounds directly on plants. To use coffee on your plants’ leaves, place one cup of spent coffee grounds in a 10-litre bucket of water, steep overnight, and use this foliar feed as a spray.
You should add 1 cup of coffee grounds to your compost once a week. More than that, and you risk over-acidification. Be sure to mix it into compost with a good balance of brown and green material.
Yes, you can recycle a coffee maker. Electronic coffee makers are e-waste and should be taken to a certified recycling depot. Upcycling or recycling coffee makers, composting coffee grounds, and recycling coffee pods are all good ways to reduce the environmental footprint of your coffee habit.
- Reich, L. (2014, April 25). The Four Things You Need to Know About Soil pH. Retrieved from https://www.finegardening.com/article/the-four-things-you-need-to-know-about-soil-ph
- Russell, E.M. (2022, March 11). 26 Plants That Like Coffee Grounds And a Few That Don’t. Retrieved from https://www.gardeningchannel.com/plants-that-like-coffee-grounds/
- Rhodes, H. (2021, July 6). Proper Compost Mixes: What Is Brown Material For Compost And What Is Green Material For Compost. Retrieved from https://www.gardeningknowhow.com/composting/ingredients/browns-greens-compost.htm