Coffee Grounds in Your Garden Soil From Master Gardener David Wall

March 17, 2024 – Many of you use your “used” coffee grounds for fertilizer in your gardens. You like the results but have to experiment to find the best way to do so. Used coffee grounds for fertilizer is not exactly a new idea. Additionally, many of you put coffee grounds in your compost piles where it mixes with other organic contents, eventually resulting in great soil additives.

It must be noted, however, that this is done with coffee grounds, not coffee liquid. Coffee liquids, at a minimum, have to be diluted (50/50) before adding to the garden or compost pile. Diluting with tap water will raise the liquid pH from a normal 5.2 – 6.9 to 6.5-7.0. Liquid coffee contains nitrogen, magnesium, and potassium which are good, but may have things added to it, such as milk, cream, or artificial sweeteners, none of which will do your compost pile or plants any good.

Used coffee grounds are great throughout the garden but are perhaps best used on tomato plants from seeds to mature plants. They will help seeds germinate faster, support growth, and let mature plants produce more tomatoes. Nutrients mentioned above in coffee grounds are in a form that in soil can easily be absorbed by tomato plant roots. Additionally, used coffee grounds in the soil absorb large amounts of water, which is then retained around plant roots, thus providing moisture for young plant seeds and later roots. Two tablespoons raked into the soil around the plant hole starts the process. Two more on top of the soil provide additional support. Nutrients will leak out of the grounds and head for plant roots.

After making your morning coffee, pour another pot of water over the grounds and save to provide additional fertilizer. Finally, the bottom line here is that this fertilizer is free!

coffee grounds

Author: Matt Janson

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