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Avatar for michaelm101
Jan 10, 2025 7:11 PM CST
Thread OP
Name: Michael
Chino Hills CA (Zone 10a)
One site says "no," another says "yes," yet another says, "only non-brewed" grounds (so, plants also like caffeine?)...

What's the real deal on this, because I don't like to see easily-collected organic matter go to waste...

Thanks as always for your excellent and helpful commentary!
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Jan 10, 2025 7:16 PM CST
Name: PotterK
Seattle, WA
We use worms. The spent coffee grounds, tea, and most veggie refuse goes to them. The worms make a fine soil additive - way better than coffee grounds fresh from the pot. Worms are easy and actually fun to cultivate.
Their compost is like garden gold. If you grow potted plants, worm compost tea fed during the growing season is like plant steroids. Get out of their way!
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Jan 10, 2025 7:59 PM CST
Name: Nick
Detroit Michigan (Zone 6a)
My kids are my life
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I regularly compost coffee grounds.

Over the years I have read far more articles talking about the use of grounds and not many speak of a real positive effect. But it is a habit with me. I guess even a minimal effect is better than no effect.
There is no better thrill then catching fish using flies that you tied!
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Jan 10, 2025 8:03 PM CST
California Central Valley (Zone 8b)
Region: California
I think it was a myth started by Starbucks. Smiling
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Jan 10, 2025 8:11 PM CST
Name: Zoë
Albuquerque NM, Elev 5310 ft (Zone 7b)
Bee Lover Salvias Region: New Mexico Herbs Container Gardener Composter
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They add tilth and texture to the soil and bulk to compost. Alone, not much value as a fertilizer, maybe barely helpful with lowering pH. In moderation, no harm that I know of.

What site says "only non-brewed?" Who's gonna dump unbrewed grounds in their garden??
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Jan 11, 2025 2:04 AM CST
Kaneohe, Hawaii
There's no magic here. Practically any organic matter is good for the soil. Worms and compost help put it into a better form to amend your soil but you can just sprinkle it in your yard so you are not contributing to waste.

Coffee itself is acidic. Coffee grounds are not. It doesn't make sense to add non-brewed coffee to your soil. You can buy a bag of potting soil for the price of a small bag of coffee.
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Jan 11, 2025 6:53 AM CST
Name: Sally
central Maryland (Zone 7b)
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I always add these to garden/compost- Maybe minimal fertilizer, but of course organic, easily mixed in and disappears. One tiny way I divert waste out of the landfill. I use the plastic coffee tubs to collect kitchen waste (grounds, scraps) and there's about one a week from me and another a week from the break room where I work.
Way too much nonsense circulating on the web, every influencer has to say SOMETHING, and surprising wrong information is just as attention getting as good information.
Plant it and they will come.
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Jan 11, 2025 6:54 AM CST
Name: Sally
central Maryland (Zone 7b)
See you in the funny papers!
Overwinters Tender Plants Indoors Garden Procrastinator Charter ATP Member Hummingbirder Frogs and Toads Houseplants
Keeper of Poultry Vegetable Grower Region: Maryland Composter Native Plants and Wildflowers Organic Gardener
Plant it and they will come.
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Jan 11, 2025 7:22 AM CST
Name: stone
near Macon Georgia (USA) (Zone 8a)
Garden Sages Million Pollinator Garden Challenge Plant Identifier
NMoasis said: Who's gonna dump unbrewed grounds in their garden??

I agree

As most of the rest of the people have posted, organic material is good for the soil. Coffee grounds included.

I've added grounds to compost, I've dumped them out on top of the soil, I've buried them... I haven't found a way that they're harmful... They add tilth to the soil, and help the sand to retain moisture, and likely help to retain nutrients as well...
Avatar for oregonmarty
Jan 11, 2025 5:45 PM CST
Name: Marty
Oregon's Willamette Valley (Zone 8b)
Aroids Peonies Tropicals Bulbs Dahlias Hummingbirder
Lilies
sallyg said: This guy- I enjoy
https://www.gardenmyths.com/co...


Interesting site; thanks Sally.
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Jan 12, 2025 12:06 AM CST
Name: Kat
Magnolia, Tx (Zone 9a)
Region: Texas Dragonflies Hummingbirder Peppers Herbs Vegetable Grower
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I use coffee grounds when I have them, they are worm candy here in the south. I do sprinkle them away from the garden because they draw the moles to a different area of the yard than my garden. The robins in Spring are also drawn to where I dump the grounds - and it is because the earthworms love the grounds. That said, organic stuff creates garden gold, tea bags were used by the Brits around their rose bushes, and the roses loved them, so again a weak tea of organic substances and the bushes didn't care if they were getting caffeinated or not, all those stuff the plants didn't use just get absorbed and thinned and diluted.
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Jan 12, 2025 6:29 AM CST
Name: Kenny Shively
Rineyville, KY. region 10. (Zone 7a)
Region: Kentucky Daylilies Hybridizer
I have used coffee grounds extensively in my garden,not so much anymore. Here why, Probably from using too many, I put them around all my plants, shrubs, daylilies, all.( I had 21 five gal buckets of dried grounds in my barn at times.).
I have no scientific proof, but notice some plants were not growing well, looked fine but not or multiplying. Particularly some China Girl Hollies that I had moved. Started doing a lot of reading on using coffee grounds in the garden. It seems some research shows that coffee grounds can stunt growth on certain plants. When put directly into the ground. Keep in mind I probably used more than should have.
I still use a few for composting, or worm food. It's good to keep them out of the landfills. I do think they have a place in the garden. Just don't over use them. Do your research.
Thank you all for the wonderful reading in this forum. Smiling I tip my hat to you.
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Jan 12, 2025 7:51 PM CST
Name: Kat
Magnolia, Tx (Zone 9a)
Region: Texas Dragonflies Hummingbirder Peppers Herbs Vegetable Grower
Heirlooms Moon Gardener Enjoys or suffers hot summers Winter Sowing Bookworm Container Gardener
Moderation in all things.
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Jan 13, 2025 6:59 AM CST
Name: stone
near Macon Georgia (USA) (Zone 8a)
Garden Sages Million Pollinator Garden Challenge Plant Identifier
kennysh said: I had 21 five gal buckets of dried grounds in my barn at times.

It seems some research shows that coffee grounds can stunt growth on certain plants. When put directly into the ground.


Yeah... I tried digging sawdust directly into the beds, I tried digging dropped tree leaves directly into the beds...

Either of these dug into the clay soil caused the soil to be unproductive for me. Surprisingly, digging sawdust into the sand wasn't problematic.

Based on my experience, I can see how having a large amount of uncomposted coffee grounds dug into the garden bed could be problematic.

If I had that amount of coffee grounds to experiment with... I think I'd use them as mulch.
Last edited by stone Jan 13, 2025 7:00 AM Icon for preview
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Jan 13, 2025 4:57 PM CST
Name: Gina
Florida (Zone 9a)
Tropical plant collector 40 years
Aroids Region: Florida Greenhouse Tropicals
This reminds me of the Beer Fertilizer fad
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Jan 14, 2025 11:56 AM CST
Name: Tiffany purpleinopp
Opp, AL @--`--,----- (Zone 8b)
Region: United States of America Houseplants Overwinters Tender Plants Indoors Garden Sages Plant Identifier Garden Ideas: Level 2
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Agree with the comment about moderation. Putting a lot of any single thing in or on the soil could be problematic.

Coffee grounds should be just a fraction of the organic matter that passes through your house/garden. I use all of it except meat/bones, big thorns, pulled weeds that already have seeds.
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Jan 15, 2025 7:06 AM CST
Name: stone
near Macon Georgia (USA) (Zone 8a)
Garden Sages Million Pollinator Garden Challenge Plant Identifier
purpleinopp said:Coffee grounds should be just a fraction of the organic matter that passes through your house/garden. I use all of it except meat/bones, big thorns, pulled weeds that already have seeds.

I bury animals in the garden... Stuff like roadkill brings unwelcome pests like houseflies...
A lot of people say that they're providing for the vultures...
and then haul the carcass to the road in front of my
house...
where it causes a lot of problems for me....
Feed the vultures at your own house!

Buried deeply enough, I don't have a problem with meat and bones. I think that the plants are able to derive nutrients... eventually.

Most of the meat and bones from in the house... goes to the cats... after the cats are finished with the bones, they go in the wood fired grill... they are eventually used with the rest of the ash in the garden... to cover the afore mentioned dead stuff.

Thorns?
Yeah, those go to the burn pile... Sometimes those burn piles turn into compost before they get burned...Around here, stuff breaks down very fast!

Plants with seeds... go to the chickens... they eat the seeds, and keep everything disturbed just like the rest of y'all with compost piles.
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Jan 15, 2025 9:02 AM CST
Name: Tiffany purpleinopp
Opp, AL @--`--,----- (Zone 8b)
Region: United States of America Houseplants Overwinters Tender Plants Indoors Garden Sages Plant Identifier Garden Ideas: Level 2
Organic Gardener Composter Miniature Gardening Million Pollinator Garden Challenge Tender Perennials Butterflies
I would do more like that if we had a bigger property. We are in town on a pretty small lot. The amount of OM that leaves the property in the form of bones or thorns is inconsequential. The yard waste truck has never stopped @ our house.
The golden rule: Do to others only that which you would have done to you.
👀😁😂 - SMILE! -☺😎☻☮👌✌∞☯
The only way to succeed is to try!
🐣🐦🐔🍯🐾🌺🌻🌸🌼🌹
The best time to plant a tree is 20 years ago. The 2nd best time is now. (-Unknown)
👒🎄👣🏡🍃🍂🌾🌿🍁❦❧🍁🍂🌽❀☀ ☕👓🐝
Try to be more valuable than a bad example.
Avatar for aloe143
Jan 18, 2025 11:52 AM CST
mid-Wales. UK hardiness zone 7
In the UK they're compressing coffee grounds & turning them into fire logs! Good compost needs to be a mixture of nitrogen (from plant materials/garden waste) and carbon (shredded paper/card, coffee grounds, etc.), but most folks overdo the green stuff. Just sprinkle the coffee grounds over your compost heap, and you'll greatly improve the final product. Just don't add citrus peels...the worms will decamp.
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Jan 18, 2025 4:57 PM CST
Name: UrbanWild
Kentucky (Zone 6b)
Kentucky - Plant Hardiness Zone 7a
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OK so here goes.... I'm about to discuss and disagree with commonly held notions.

First, compounds added to the soil go far beyond simple npk concerns:

https://www.sciencedirect.com/...

That said, you're right.... Websites, YouTube videos, etc all have conflicting statements and most seem geared towards making clickbait.

As a few have mentioned here... Coffee grounds and spent tea are written candy. More on insect use later.

There are times when I've been given old, never brewed coffee. I've used that as well in the compost or mixed with polar shavings to feed fungi for mushrooms.... Then to use the resulting matrix as mushroom compost.

Regarding moderation...I don't follow that. I have a neighborhood coffee shop I have a deal with and I average 25-30 GALLONS of spent coffee grounds (and small amount of spent tea leaves) a week. I gleefully add that not only to compost but also directly into existing beds, containers, etc. I also use fresh grounds with poplar shavings as mentioned above. The result has been turning a nearly barren, lifeless compacted old urban lot into a haven. It isn't simply the use of coffee but the coffee is an integral part.

Caffeine and worms... Hasn't been an issue in the slightest. My beds and compost bins are absolutely teaming with life. I get worm castings as part of the compost and as part of everyday life in the beds. And that brings me to...soldier flies...

Yellow soldier flies and black soldier flies are a fundamental part of my composting and soil-building efforts. One thing I noticed 9 years ago is that areas where I dumped more coffee, got far more attention by soldier flies. They process larger bits like nobody's business. So in my composting, bacterial changes happen first. Then soldier flies and other large processors have their way. But the communities I get in coffee rich areas make it a soldier fly world. I get faster processing and enrichment. They make it a bit more mucky than the worms like but the worms are always getting at the edges. The muckiness moderates as they move away from those areas they find played out. But nothing reduces piles like soldierflies. That noted, I started experimenting. And basically what I found was there is no upper limit of spent coffee that makes things go bad in my system. I've even done well with beds of nothing but coffee grounds. That said, I much prefer mixed/layered efforts as I think the rewards are sweeter. Anyway, in my system, no amount of coffee is too much. My shop is 3 blocks away and I probably pick up twice a week, year-round, mixed with other errands. They're good to me and I don't leave them hanging. They text me when they need a pickup.

Anyway, the result of the large coffee component has been terrific tilth, candy for the invertebrates who produce thinks like castings, and all those soldierfly adults and larvae make food for a host of predators both invertebrate and vertebrate. There might come a day when I decide to ratchet back on the coffee, but that day is not in sight. The resulting plant growth, the rich and diverse soil communities, and ability of the soil to grab and keep moisture is testament to something going right. I'm not saying everyone needs the same volume of coffee grounds I've used, but I have seen nothing to suggest it had a downside and coffee seems to have numerous benefits. My results are anecdotal but there is far more specific science in them than I see in most, if not all, of the popular sites.

So, as a science dork I generally go down the rabbit hole for more concrete info. But not a lot exists with coffee grounds. I experiment a lot and build on it wherever I can. But if you look at the numerous YouTube videos all saying the same conflicting statements, it's clear most seem to be parroting things they've heard somewhere or watched in other videos.

YMMV... But I'll quietly keep saving loads of coffee from the landfill and making my soil community happy.
Always looking for interesting plants for pollinators and food! Bonus points for highly, and pleasantly scented plants.

"Si hortum in bibliotheca habes, nihil deerit." [“If you have a garden and a library, you have everything you need.”] -- Marcus Tullius Cicero in Ad Familiares IX, 4, to Varro. 46 BCE
Last edited by UrbanWild Jan 18, 2025 7:55 PM Icon for preview

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