A Guide to Making Garden Fertilizer from Coffee Grounds

There are many ways to transform used coffee grounds into gardening gold. Here are five suggestions to get you started.

Gardeners love the opportunity to save money, and few things can beat the convenience or cost-savings of using a waste product to promote plant health. That’s the beauty of coffee grounds. Savvy gardeners can save up a supply to improve soil health and grow healthier plants.

When applied correctly, coffee grounds will add critical nutrients to garden soil (nitrogen, calcium, potassium, phosphorus, magnesium, and more), reduce compaction, boost moisture retention, and attract earthworms and other beneficial soil-dwellers.

The secret here is knowing how to correctly apply coffee grounds. There are multiple strategies for using coffee grounds in the garden — here are five recipes to experiment with.   

Note: If you don’t drink enough coffee to build up a grounds collection, consider checking in with local coffee shops. Many are thrilled with the opportunity to skip the trash and pass on bags of spent coffee grounds to gardeners that can use them. 

How to Make Homemade Fertilizer with Coffee Grounds
Recipe 1: Coffee Grounds, Cinnamon, and Seltzer Water

This internet-famous composting recipe requires three basic ingredients: used coffee grounds, cinnamon, and seltzer water (although filtered tap water works just as well).

Recipe 2: Add Coffee Grounds Directly to the Soil

If you want to keep things simple, it’s possible to skip all intermediary steps and add used coffee grounds directly to your soil. Some people prefer to work them into the top few inches of soil, while others sprinkle them on top and allow the grounds to slowly work their way in.

Just make sure you scatter them in thin layers. Too large of clumps can create water-resistant crusts on top of the soil.

Recipe 3: Make Coffee Ground “Tea”

Compost tea is an ideal way to boost soil’s nutritional content. Turn spent grounds into a tea by adding two cups to a five-gallon bucket filled with filtered water. Let the blend steep overnight before applying directly to your plants. If you want a foliar treatment, filter out the grounds and pour the liquid into a sprayer to treat the leaves directly.

Recipe 4: Incorporate Coffee Grounds into a Worm Bin

If you have a worm bin already established, coffee grounds can make for the perfect addition. Add a cup or so at a time so you don’t overwhelm the worms with acidity, and they will work quickly to transform them into worm castings — a potent natural fertilizer.

Recipe 5: Turn Coffee Grounds into Compost

If you’re OK with delayed gratification, consider adding coffee grounds to your compost pile. Despite their coloring, the grounds qualify as a “green” material and will balance out materials like dry leaves and newspaper. Give them a few months, and the grounds will break down into a beneficial soil additive you can add to garden beds as needed.