Knowledgebase

coffee grounds #808368

Asked August 28, 2022, 1:09 PM EDT

Recently there was an article in the dispatch that said coffee grounds are bad for the soil. It mentioned not to put them in the compost bin nor into the soil. It said that would harm the plants. I have a vegetable garden and have been using coffee grounds for years. Also, I have always been told that coffee grounds were good for the soil. Is this research something new? Can you comment on this, and have you seen the article?

Franklin County Ohio

Expert Response

I looked for the article you mentioned and found the following recent articles in the Dispatch:


Compost Clubhouse inspires Columbus-area kids to reconsider food waste (dispatch.com)


Composting is a great way to help add organic matter to soil (dispatch.com)


Coffee ground, literally | Ohio State Sustainability Institute (osu.edu) None of them say anything about coffee grounds being bad for the soil, nor do any of Mike Hogan’s articles that I remember reading in the Dispatch (which I always enjoy and know that he’s quite knowledgeable).


I read several recent articles from universities and they all agree that coffee grounds improve the structure of soil, and add nitrogen and other nutrients. If you’d like to read what the experts say, you might enjoy Using Coffee Grounds in the Garden | Cooperative Extension | The University of Arizona, Coffee grounds cover a lot of ground - AgriLife Today (tamu.edu), and Coffee Grounds and Composting | OSU Extension Service (oregonstate.edu). Anyway, keep adding coffee grounds to your garden. I’m sure your plants will appreciate it.


I am referring to the article in the Dispatch on Sunday, Aug. 21th  , 2022.. The title isCOFFEE GROUNDS won't perk up your plants.This is the article that says coffee grounds are not good for the sale. Can you check this out and give me your opinion?
On Mon, Aug 29, 2022 at 7:57 AM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied August 30, 2022, 10:43 AM EDT


Thank you for the information concerning the title and date of the article. It helped me locate it. It was interesting but said most of the same information you will find in the articles I suggested you might like to read. She skewed her information to talk about the little amount of nitrogen in coffee grounds but didn’t mention much about the other nutrients and she wrote about the possible negative effects of coffee grounds. I realize there is little nitrogen and it’s slowly released but am guessing it’s not the only fertilizer you use. The only additional comment she made was concerning caffeine. I found a few research articles about the effect of caffeine on plants. While they all seem to conclude excessive amounts of caffeine may stunt the growth of some plants depending upon how it is applied and that more research needs to be done, they seem to say that the small amounts we put in our gardens can be helpful. If you’d like to read more information, I would suggest fs207e.pdf (wsu.edu) which goes into information about how to safely use coffee grounds in your garden and suggests not putting them on seeds which may inhibit some germination. Also, Fernando-Diaz.pdf (southmountaincc.edu) and UCSB Science Line
talk about scientific experiments that have been done to determine the effects of caffeine on plants. I think after you read a couple of the articles I’ve listed you’ll want to make your own decision.





Can I put leaves from a walnut tree in my compost?  If not, what percentage can I put in?   I have walnut trees in my backyard.  I try not to get them in my compost, but I'm not sure how successful I am.
On Tue, Aug 30, 2022 at 4:32 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied October 26, 2022, 11:34 AM EDT
Hello,

Yes, you can add walnut leaves to your compost. The toxins in the leaves break down in a matter of weeks and will not be a problem for future plants that are grown in the compost. If you would like to read more about walnuts and their toxins, please visit: https://www.extension.iastate.edu/news/2005/jul/070701.htm#:~:text=Walnut%20leaves%20can%20be%20composted,walnut%20tree%20has%20been%20removed.

Beth Scheckelhoff Replied October 31, 2022, 8:39 PM EDT

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