Yup worms love wet coffee grounds.... though I just saw some clip thing on discovery channel about UCG killing worms in you compost bin. I’ve loaded tons of UCG from Starbucks into my compost and the worms go nuts for them... so I don’t know where they are collecting the data from

I've never heard of coffee grounds killing earthworms. Quite the opposite! I'll have to look for the video. The remaining caffeine--not much--shouldn't be enough to negatively impact anything. And after a rainfall or two, nope.

I don't have much first-hand experience here (we both detest coffee and I can't even tolerate the smell, which to me is of burned beans) but everything I've ever heard is that most compost critters love coffee grounds. They're moist. They have some nutrients--not much, but some. They taste good to them (they can have the durned things for all I care!).

For years, I've recommended that even if people don't compost them, they toss the grounds out onto the lawn or into the gardens each morning, or put them into a pot outside (these can be used inside in judicious quantities, but will decay via fungi primarily so I'd mind the amounts used per indoor pot per month). If they have to throw away the filter or pod, so be it, but the grounds, at least, are a very useful organic.

mmm... yummy burnt beans. I wasn’t a coffee person until just a handful of years back And I will say maybe you just need to taste a wide variety of brands. Many times people at work, the company would get taste test variety packs... and many of them I couldn’t even finish a cup because it tasted so bad.

now... back to worms... after seeing the bit on the discovery channel... I had to look it up too. I I use to bring used coffee grounds and spread 5 gallons of the stuff at a time across my lawn and or compost. The worms loved them and the lawn seemed happy.... but the link refers to studies showing that coffee ground and thsir caffeine (even in used grounds) can kill worms and stunt plant growth. They link to studies about these effects

https://www.discovery.com/science/Coffee-Grounds-in-Your-Garden

You will find baby worms just as tightly congregated in an eggshell half as you will a coffee pod.

Fortunately, given that worms end up in coffee grounds kind of implies that they don't die in there all that easily. :-) Given the broken citations and not-so-great use of their actual scientific citations (8mg/g caffeine is not very toxic to most creatures, for instance, and in compost, that's going to leach and diffuse), I'm going to call this dubious and continue to use them.

If one is concerned, then by all means, scatter the grounds in the compost rather than putting them in as a lump. Or rinse them a second time to reduce the caffeine yet again.

I've heard that the right mix of coffee grounds and bedding in a small worm bin can heat up too much. I don't really buy the caffeine thing, but what do I know? From my somewhat limited experience with worm bins, too much of any one thing can be bad. Worms do seem to like it, but I'd guess @annpat 's comment is on the mark - environment baby worms seem to like; but then coffee grounds are made for worms to eat them.

Coffee grounds I'll always just throw directly on the yard, it looks enough like soil. Never had access to the kind of quantities that some here have, but I'd take a truckload if I could get it (for free).

"I've heard that the right mix of coffee grounds and bedding in a small worm bin can heat up too much."

Tru dat. Add greens and it's a real mess, just like any other bin. I did once get some from Starbucks and drop them in a bin--I was motivated--with garden waste.

I clocked that puppy at 165, so the bin core was self-sterilizing and I was mildly worried about a supernova. :-)

"Never had access to the kind of quantities that some here have, but I'd take a truckload if I could get it (for free)."

Most Starbucks have a Grounds to Compost program. Call, but they do save them. If you get lucky, you...won't get a truckload, but you will get plenty. Take several large buckets. Even on a standard day, you'll get lots.

Since The Plague, I haven't been by, and don't make a habit of it even when there aren't deadwagons driving past. There are no local 'bucks here in the boonies and I don't often think of it, plus, as noted, I loathe the smell.

I do discard my loose teas in the garden, but those are much lower in caffeine anyway (although I live on iced tea) even though I only lightly steep at lower temperature. Given my sensitivity to caffeine (nil), I wouldn't be able to tell what I'm getting compared to the potential. I can guzzle the stuff and take a nap.

I'm also in a 'bucks-free zone, so no luck there.

The one point I'd add (as so much in compost): quantity matters. Whatever the hypothetical negative effects of caffeine, I just doubt many are going to add so much spent coffee grounds as to hit the level where it makes much difference.

Okay, if you're spreading it several inches thick, or when I get that free truck load, maybe read that paper.

Back when I was getting buckets of the stuff and adding it to the compost bin... I would get plenty of sections that were a few inches thick of just UCG.... the red worms loved the stuff. Maybe the issue is that worms have a high rate of illiteracy and they just don't know how to read the study?

One thing they do point out is that UCG can reduce plant growth (from caffeine). Maybe this coming season I will do a test and see if that's true to any extent.

I suspect that we need to fund a literacy program for the worms in this instance, but perhaps ignorance is best and we might want to let them simply eat the UCG, the study, and possibly the researchers as well. :-)

Honestly, I can say that overapplication of some things can stunt plant growth. Unquestionably. I've done it with kelp by accident by overapplying it by factors of...well, lots. The same way glyphosate can be used as a growth regulator for many plants (without phytotoxicity), kelp will begin to negatively impact growth rates if overapplied; the growth rates turn negative at about quadruple normal app rates.

That might be useful in terms of dwarfing a plant in a pot, but I've never done a specific experiments and checked top and root growth to make sure that the roots are healthy and proportionate.

I've neither seen nor heard of issues with UCG, so I suspect the amounts used have to be ridiculous, or applied with very little irrigation/rainfall to leach out the material through the soil. Neither is going to be an issue for me.

I worked in a food processing plant for 37 years.We processed coffee for a major Food group. I composted & add raw coffee into my garden, never had a problem.

I had whole green beens, roasted whole beans(not true beans), ground coffee not used & used ground coffee & coffee chaff. I put it down 6 inches deep around my tomatoes & had the best crop in 40 years of gardening. The coffee waste I used had decaffeinated coffee & caffeinated coffee, the decaffeinated process was used with steam, not Formaldehyde.

That maybe the difference in their finding & my great success with all kinds of coffee waste for years!

I'm loathe to brag, as you know, but my Starbucks showed me where their coffee grounds dumpster is.

Objectively, I don't think you are actually loth to brag.

If it works for this forest, can't see why it wouldn't work in my yard:https://www.upworthy.com/researchers-dumped-tons-of-coffee-waste-in-a-forest

Unfortunately I don't have enough coffee grounds available to me but my grounds do go straight to the yard.

In the 70s, I worked in a busy restaurant and was able to bring home huge amounts of coffee grounds daily. For Christmas one year I gave my gardening brother and my gardening stepfather each a large new garbage can filled with eggshells and coffee grounds. I'm not sure they were as pleased as I would have been.

I teach worm composting for the city and county and we always put coffee pods in. They love coffee.

Do worms suffer from caffeine withdrawal headaches though? I guess not clear whether they have 'heads' at all, but still.

I teach worm composting for city and county and we always add them to our bins. Actually worms lay eggs and about 2-3 weeks later they hatch and babies are on their own.