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)
Coffee grounds scattered in the garden deter slaters
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I am not a coffee drinker but was given some ground coffee- so, I was wondering if I can use un-brewed coffee grounds or if that would be too strong for my plants? must it be used coffee grounds or is any form of coffee good enough? thanks for the feedback!
Hi Jordy, thanks for leaving a comment. I’d suggest you avoid using un-brewed coffee grounds because they still have the caffeine in them, and that can cause all kinds of problems for the plants and soil. If you don’t want to drink the coffee, then maybe pour it into a compost bin or worm farm and the microbes will take care of it for you. Then use the brewed grounds around plants with no concern.
If in drought let it decompose somewhat. Boiling it ,I think, is a step in decomposing. Put them in a pan ,boil them , then use them. [?]
Sure thing – as long as you first get the caffeine out of the grounds before you use them directly on plants.
Based on my experience; caffeine is not a problem.
Thanks Gene – will start my experiments!
T E S T : In a wheel barrow I put 5gal each of : coffee grounds , sea weed- kelp , & yard clippings[carbon]. The different parts had gone thru a chipper. I then added a hand full of ”red” worms. .The worms are doing just fine ; thank you. I have faith, trust & respect for mother earth. No mater ”what” we giver HER ,She will deal w/ it. Just use your head. Yes ,to much sea weed could be a ”problem”. Decompose is the key; keep damp. I started the test over a moth ago.
I live near the pac. ocean; w/ access to sea weed & kelp. So how would you apply this to the mix w/ coffee grounds ,etc. ? From a coffee shop I get 5gal per day. I like what I am getting from the grounds so far. Hoarse manure from a local stable.
Sounds like a great combination, I’d wash the seaweed you collect with fresh water, then add to the grounds and horse manure. Only issue might be how long you want to prepare that mixture because it might take a while to break down. Please let me know how it ends up, because there are very few people I know of that have combined those three ingredients. Assuming that the horse manure has plenty of straw or carbon material on it already?
Thank you for the reply re: ”KELP”. Yes, a part of the mix IS carbon from the yard; after I
put it thru a chipper. Washing “it” : are you concerned about the salts?
Yeah it might be a problem with soil but also in how quickly it breaks down. Washing it might avoid both of those.
Thanks for the info, have not seen anywhere else about the coffee grounds as a fertilizer aspect in so much detail.
Yeah that is what I tell people also Bianca 😉 I think this is now the biggest site on using coffee grounds for gardening.
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I have used my coffee grounds in soil & tea grounds for 20 years, for 3 years I have been using at least 2 dump truck loads of coffee chaff & some coffee mixed in.
I have one problem, can I freeze & gave all the crops away. Mostly that is a little problem & I will do my first soil test in 10 years this spring of 2011.
I know you should do one every 4-5 years, but things grow, so I do not need one. Making fertilizer from spent coffee grounds is great. 🙂
But with all the chatter on the net, I guess a ST would help state my case.
Thanks for the feedback Joe. Can’t say I’ve used as much ground coffee for plant and soil fertilizer as you have, but there is always hope! Best of luck with all your coffee grounds adventures Joe.