Making use of Ground Coffee for Fertilizer
There is an almost limitless amount of used ground coffee available to use as a fertilizer. To understand our topic better, let’s first understand the definition of fertilizer:
“Any of a large number of natural and synthetic materials, including manure and nitrogen, phosphorus, and potassium compounds, spread on or worked into soil to increase its capacity to support plant growth.”
Where things become tricky is that ground coffee has the nitrogen, and not that much of the phosphorus and potassium. Based on a NPK analysis for coffee grounds from the North Carolina State University, the ratio is 2.1:0.3:0.3. Those figures can vary slightly, but it’s clear that ground coffee is nitrogen heavy.
When we consider ground coffee, it is as a nitrogen fertilizer that counts. In a report titled Vermicomposting with Spent Coffee Grounds (Roekle et al):
“It is our estimation that vermicomposting with spent coffee grounds can be scaled up for a variety of profitable uses, including direct application for farm fields, greenhouses, lawns and turf grass, nursery plants, and other soil-related industries. Moreover, we believe this technology could offset the use of natural gas as a critical raw material to produce nitrogen fertilizer.”
So if ground coffee as a fertilizer is nitrogen specific, you are going to need to balance this out with phosphorus (blood and bone, poultry based manure), and potassium (animal manure). Throw in some liquid seaweed concentrate, lawn clippings, other organic materials as you find them, including worm castings and the leaves, stalks, and roots of current and past crops.
Ground coffee as a fertilizer might not be a balanced one, however let’s summarise some of the benefits of using the grinds:
- Attracts and feeds earthworms
- Loosens the soil
- Retains water
- Deters snails, slugs, ants, and cats
- When added to compost (up to at 25% total volume), will improve the whole stack and speed up decomposition
- Reduce soil borne disease
- A cost free soil amendment
- An easy way to reduce landfill and get you out into the garden
- Can be applied directly to the garden, into compost, on the lawn, or in liquid form to pour over into the soil
A pepper growing in my garden, with thanks to ground coffee. If you are looking to get started in the garden and need a fertilizer, consider it as a good way to get started. It won’t do it all without a little help, so go grab whatever you can.
What Others Are Reading
- Coffee Grinds in the Garden (groundtoground.org)
- Coffee Grounds (groundtoground.org)
- Collecting Coffee Grounds in the Office (groundtoground.org)