How much coffee grounds do you feed?

jasdipAugust 17, 2010

I don't bother with coffee grounds in my bins. I don't find my worms care for them. When I did, I tried putting some grounds in a corner, and the worms didn't party in it at all.

I'm also afraid of getting the bin too acidic. I get enough mites as it is, and I did notice that they are attracted to coffee grounds in the past.

Anyway, I've been asked how many grounds should be fed to a pound of worms. A large source of grounds is available, and I honestly don't know what to tell them.

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antoniab(5 WofChicago,IL)

I have noticed that they do heat up. However, some people love using them. There are mixed results about the pH of coffee grounds too. I have heard that they are almost pH neutral, but this source says differently:

What i think is that it depends on the coffee, the way it is brewed and so on. In the link, they tested 8 oclock coffee brewed in a large office coffee pot. I use organic, fair trade coffee, ground fine, and brewed dark, and when I have tested my freshly brewed grounds with a soil testing tablet, they come out to about a 6 or 6.5. I would imagine grounds from a french press would be different than those from Starbucks too.

Anyhow, I do know that some people do feed a large amount of Starbucks coffee grounds to their worms, since they have the grounds for gardens policy. If I get a large bag, I tend to dump it straight on the garden, around the berry bushes or whatever, not the worm bin but other people feed it to the worms without apparent problems.

    Bookmark   August 17, 2010 at 10:51PM
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plumiebear(z9? CA) didn't mention the quantity in the other forum. I got ~80 lbs. of UCG from a local coffee shop a while back and mixed it in with horse manure to sit for a while. I'm gradually mixing some of it into my regular compost bins. I don't give straight grounds to my worms. Like you said, they don't care for it "pure". Don't some plants like coffee grounds?


    Bookmark   August 17, 2010 at 11:02PM
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plumiebear(z9? CA)

Antonia, that's an interesting link. Now I need to test the grounds I have from my local shop vs my own. It looks like mostly spent espresso pucks. The study I've had stuck in my mind cited the pH 6-6.5 that you observed with your own grounds.


    Bookmark   August 18, 2010 at 12:34AM
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I use alot of coffee grounds, mostly in my regular compost bins, but I also scatter a fair amount around some of my plants and even across the lawn. I've seen no adverse effects in those areas.

As far as my worms are concerned I add a cup or so of UCG from Starbucks to each bin probably two or three times a week, particularly in my Flow-thru's. While the worms aren't swarming over the grounds, I sure they are consumed as they begin to decompose along with the paper/cardboard bedding. I figure they are at least a decent nitrogen source for the bacteria.

    Bookmark   August 18, 2010 at 10:45AM
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Periodically I mix up a batch of worm food and spread over my in-ground worm pits. The 'food' consists of horse/steer manure, UCG, kitchen scraps, paper shreds. These are mixed and allowed to mellow for a time and then spread across the surface of the pits. The worms seem delighted.

    Bookmark   August 18, 2010 at 2:36PM
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gardenfanatic(MO zone5b)

If a person has access to a large quantity of grounds and wants to use them, they'd best be used in an outdoor compost pile. They definitely will heat up.

I mix coffee grounds with damp shredded leaves as bedding, but not in large quantities.


    Bookmark   August 21, 2010 at 10:30PM
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Enough for a pot of coffee on Christmas and Easter.
If I had enough I would cover the beach sand lawn half an inch thick in them.

    Bookmark   August 25, 2010 at 9:33PM
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I usually don't add anything straight to my worm bin but compost it initially for a short period in my hot compost bin. Doing this first, I find makes the partially composted coffee grounds (and every thing else) very appealing to the worms.

Here is a link that might be useful: Backyard Farming the Natural Way

    Bookmark   October 13, 2010 at 9:03PM
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Karchita(WA Z8)

I feed my worms kitchen scraps, which in my household consists of a lot of coffee grounds in paper filters. I have never had a problem with them heating up in the bin and they all get eaten just fine, along with the paper filters and everything else. I've been doing this for 8 years or so.

It is hard to tell coffee grounds from finished worm compost at times, but if it isn't quite finished when I put it on my plants, there's no harm done.

I get UCGs from Starbucks and put it on my lawn 4-5 times a year and I use it in my hot compost bins for a green. I also use it to lightly topdress (1/4" at the most) certain plants that need a lot of nitrogen, like hostas and ornamental grasses, in the spring. It seems to repel slugs a bit, so that's another plus. The grounds from SB are not acidic, but I have long suspected that the acidity depends on the type of coffee and the brewing method. Nice to see some support for that idea.

    Bookmark   November 7, 2010 at 12:35AM
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Mine love UCG and I like the quality of VC produced. I used to be collecting the grounds from my office. (New secretary, I don't want to ask that kind of favor yet.) I can't give any advice on quantity, though. The UCG from one large pot a day in my small FT bin worked well along with vege waste and bedding.

As to pH, my understanding is that worms can tolerate a VERY wide range of pH, but they can't tolerate quick changes. I think Bentley had a UCG/bedding only bin. I know he had a HUGE pile of UCG. Search on and you might get more of the type of info you're looking for.

If your friend wants to do predominantly UCG and bedding, then I would think the 'half their weight a day' (or somewhat less for most of us) would be a good place to start the thinking. I would also think that the weight would be wet weight, since veges are obviously weighed with the water still in them. As with any other food, start slowly until they're used to it.

    Bookmark   November 7, 2010 at 9:01PM
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my daughter and i did alot of research about a week ago online. the general thing we noticed was it depends on a couple things. in the end we came to the conclusion that starbucks coffee grounds, (they give away the used for free just ask for it) are PH 5. how ever i can't say all coffee is the same. with that said if you are putting coffee straight from a new can of coffee into your bin thats more acidic. the acid is in your cup of coffee not as much is in your already used coffee grounds. yes they do heat a bin fast and hot!! i am trying my own experiment. i have a 4'x4'x4' wood bin, it sits in my back yard. we do get cold weather here in upstate ny. i am using alot of used coffee grounds, one bail of straw, alot of shredded leaves, newspaper, cardboard (courigated and egg cartons, drink tray), as well as kitchen scraps as much as i can get, i also begg my friends, relatives, neighbors. my goal is to keep my bin from freezing using no man made heat. so far i have a 20 to 30 degree temp warmer inside my bin from out side temps. so far so good, the bad weather still ahead. enjoy your worms, hope i have helped at least some. good luck all!

    Bookmark   November 7, 2010 at 9:09PM
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I bet it is not if one adds coffee grounds or citris but if one adds enough bedding to balance coffee grounds or citris.

upstate ny: maybe add a bit of insulation. I have great hope for your using no man made heat method and hope it works out so we can all use it. Maybe a simple hoop house or tarp?

    Bookmark   November 7, 2010 at 11:26PM
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I add coffee grounds nearly daily. Every time I change the coffee grounds in the filter I dump them straight to the worm bins. I have 2 in particular (out of 6) that I dump grounds in because I don't put other stuff in as often.

Worms will also eat according to the environment. Too high of temps or too low will cause them to stop eating as much. I notice that when my bins are around 72 or so they eat almost faster than I can feed them. 10 degrees either way and I'm storing scraps, including the grounds, in a freezer bag.

    Bookmark   November 8, 2010 at 11:47AM
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