Coffee grounds more acidic than the are thought to be?

15 years ago

http://www.gardensalive.com/article.asp?ai=793&bhcd2=1221669272

"It turns out, as expected, that "coffee grounds alone are highly acidic," says Will, who saved all the grounds from his LabÂs break room for a week recently just to test for us ("Eight oÂ Clock" coffee, which I remember fondly from our old A & P neighborhood supermarket). They came out at 5.1, a perfect low-end pH for plants like blueberries that thrive in very acidic soil. "But thatÂs the most gentle result weÂve ever found," Will quickly added, explaining that the other 31 samples of raw coffee grounds theyÂve tested over the years all had a pH below 5, too acidic for even some of the so-called acid loving plants. "

"And he certainly doesnÂt think grounds should be used in their raw form. First, he explains, they are so acidic and so Nitrogen rich that you risk creating a Âmold bloomÂ where you spread them. And second? "ThereÂs no life in those grounds; its all been boiled or perked away.""

I always had the impression that coffee grounds could be applied directly and that all the acidity had been boiled away into the cup of coffee

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Comments (6)

takadi
Original Author
15 years ago
Also this guy seems to suggest that coffee grounds are too nitrogen rich to be applied in raw form. I got the impression, especially from this forum, that organic material are all slow release
Kimmsr
15 years ago
According to studies done by Oregon State University the pH of coffee grounds falls in the 6.5 to 6.8 range. I think I would find that study to, similar to one done by Washington State University for Starbucks, to be a more reliable source of information.

Here is a link that might be useful: Nutrients and pH of coffee grounds
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grayentropy
15 years ago
Read closely.

the other 31 samples of raw coffee grounds theyÂve tested over the years all had a pH below 5

And he certainly doesnÂt think grounds should be used in their raw form. First, he explains, they are so acidic and so Nitrogen rich that you risk creating a Âmold bloomÂ where you spread them. And second? "ThereÂs no life in those grounds; its all been boiled or perked away."
petalpatsy
15 years ago
Starbucks UCG are mostly expresso pucks. They've been ground exceedingly fine and pressure brewed, to boot. They won't be comparable to coarsely ground, drip brewed home coffee.

I certainly hope there's no life in the grounds. :O

Our Starbucks also puts out their regular grounds,in regular double garbage bags, with filters included--but now that I think about it, they never apply the nifty garden label on it, the one that states the pH. They just do it by popular demand for us composters.

I've never spread a lot of regular grounds straight to my lawn, but I've scattered a few. I've not had any noticable problems, no mold. I've also put a few directly on my rhododendrons, again no obvious problems.

I haven't had my soil tested lately from these areas, but I also put on so much of my own compost, any testing now wouldn't show the effect of a steady diet of lots of straight regular grounds with no other amendments.

I don't think I'd recommend spreading a half inch of regular grounds, uncomposted, straight on the lawn. Not even a quarter inch.

Does anybody do that? More importantly, does anybody buy little bags of compost from GardensAlive?

I don't think newpaper ink is toxic, but it's bleached and dioxins are bad. BAN NEWSPAPERS! Yeah..... Seriously, once I have a newsprint, that comes as junk mail I didn't ask for, it either goes to a landfill or my compost pile.

I agree leaves, straw, and sawdust beat newsprint as a brown for my compost. But nobody puts sawdust in my mailbox every day for me to deal with.
timbu
15 years ago
This year, I applied used espresso grounds directly under a hydrangea, the plant seems to enjoy it. (Thanks, GW!) It hadn't bloomed for 2 years - shocked by frost, or possibly not happy about the limestone edging, or having its nutrients taken away by tree roots, or a combination of all three. It bloomed well this year, so I guess I'll be giving it more coffee grounds next spring.
Kimmsr
15 years ago
If one were to buy coffee grounds at the grocers and apply that to the soil those coffee grounds might have an acidic pH, but I doubt anyone would do that since it would be a very expensive means of fertilizing. The coffee grounds that have been brewed are the ones that most people use and these are the grounds that have the pH of 6.5 to 6.8. I know many people that have taken these coffee grounds and applied them to plants and are simply amazed with the response from the plants adn the explanation is that the soil these plants are growing in now has some, maybe not much, organic matter.
Coffee grounds would be one, of many, type of organic matter to add to your soil and they are a good addition and do not have any affect on soil pH contrary to much misinformation posted on the web. They do not need to be put only around plants that need that low soil pH, but can be used any where in the garden, with no fear of doing something harmful.

Coffee grounds more acidic than the are thought to be?

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takadi
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Kimmsr

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Coffee grounds more acidic than the are thought to be?

Comments (6)

takadiOriginal Author

Kimmsr

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grayentropy

petalpatsy

timbu

Kimmsr

COMPANY

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takadi
Original Author