Coffee in the Garden

In our realm of the coffee industry we create an amount of waste or byproduct that would be expensive to dispose of in our refuse containers and it is not really trash. So, what do we do with it..we give it away for FREE! And free is my favorite price for most anything, especially for something I can use to make another item better. Used coffee grounds and coffee chaff are the byproducts that we love to give away which make your flower and garden beds better.

Seedlings sprouting through coffee compost

Soil pH and soil types change from area to area and can vary slightly on one piece or property. Differing results of coffee grounds pH range from mildly acidic to neutral to mildly alkaline. With the fact that coffee grounds might not have a stable pH, a safe choice would be to compost them first. Using composted coffee grounds has positive benefits to the garden bed: the adverse effects of phytotoxic compounds (caffeine, tannins, and chlorogenic acid) is reduced, Nitrogen and Potassium uptake in plants was shown to increase, the carbon to nitrogen ratio is reduced to a more plant friendly combination, and it adds organic matter to the soil. Some studies on coffee in the garden state that composted coffee grounds can be added at concentrations at or above 10%.

Fresh used coffee grounds can be added to the soil without composting, but in concentrations at or below 2.5%, results show. The nitrogen, potassium, phosphorus and other mineral content does benefit plant growth at that level. The organic material level is increased and while they decompose, as well as attracting beneficial organisms from bacteria to earthworms. And we all know how valuable earthworms are in your soil!

Kale and coffee compost

Coffee chaff is a thin membrane that comes off the coffee bean during roasting and is very light and dry. A Cargill lab analysis gave us a glimpse of its potential usefulness in the garden. I roast coffee and do not interpret science speak well, so I found someone who does. Gary Kline at BLOSSOM Consulting Services reviewed the analysis and gave me his professional opinion as to using chaff from coffee in the garden. He felt that the fiber content was at a good level for moisture retention and an energy source for beneficial organisms (microbes and earthworms). The nitrogen level happened to be similar to composted cow manure (which is good stuff too). Gary also said that minerals of calcium, magnesium, potassium and sodium in chaff play important roles in fertility control and plant uptake. He also recommended adding it to the soil up to 10% of the topsoil by volume.

Onions growing in coffee compost

Fresh used coffee grounds, coffee chaff and unroasted coffee beans can also be used as a mulch to cover the soil around plants. A layer no more than inch can aid in weed reduction, moisture stabilization and some mild pest control. Articles, studies and lab analysis on coffee in the garden show that used coffee grounds or coffee chaff can be used in conjunction with other amendments and they do provide positive organic material and minerals benefiting soil composition and health.

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Photos courtesy ofWoodbine Farm