I don't and wouldn't - but you certainly may if that is what you want. You can also use them directly in the garden or in an outside compost pile.

I include spent coffee grounds with every feeding along with several other food stuffs - I don't use it by itself. My worms eat it up. I do add water to the grounds so they are moist when I feed them. As for how long the grounds are steeped, my guess is most coffee makers brew at the same speed.

I also think moisture level has a lot to do with it. I've noticed piles of spent coffee grounds dry up quick and are largely ignored. But coffee grounds mixed into wet food or through overly wet bedding just disappear.

One thing I don't like about coffee grounds is they can stain material they come into contact with. This doesn't hurt the vc any, but if you're trying to learn what breaks down at what rates under what conditions, it's a pain in the butt. "Is that nearly black because it's rotting fast, or because it's full of coffee?" Ugh.

Since I drink coffee every day I will add the used grounds and filters, not every day maybe every other day or every two days and have seen no ill effects from doing it. If you put too much coffee grounds in said bin it could heat up to the point of causing problems for the worms.

My worms don't love coffee grounds, but they don't hate them, either. They seem to get eaten in a reasonable amount of time if I mix them in with other food or spread out a bit. A big bolus of coffee grounds seems much less attractive to the worms and is really slow to break down in my bin. I made the mistake of pocket feeding grounds in the beginning and found that same pocket still there a couple months later with added stench.

I also always mix in some ground eggshell with the coffee grounds. I don't know whether that's necessary for the worms, but I have the eggshells, and I figure they might help with any potential acidity problems from the coffee. Plus, the worms like the eggshell.

<<Jon Biddenback: One thing I don't like about coffee grounds is they can stain material they come into contact with. This doesn't hurt the vc any, but if you're trying to learn what breaks down at what rates under what conditions, it's a pain in the butt. "Is that nearly black because it's rotting fast, or because it's full of coffee?" Ugh.>>

I find that if coffee discolors worm food, it stains it brownish. It's a very different color than the deep, rich, warm black of something well on the way to becoming compost. Maybe this is a function of the peculiar chemistry in my bin or something.

...or maybe your particular choice of roast? and grind.

My wife is the coffee drinker and she prefers the drip method... and gets a really fine grind. I don't know the particular blends she uses but the grounds are so fine that once I mix it into any thing and add it to the bins, it disappears... is it being consumed? or just scattered? don't know. In the beginning I tried to feed straight coffee grounds (and filter paper) and the grounds just sat there in a pile... eventually I would turn over the bedding and found once it gets mixed into something, anything, it disappears. Is it because the grind is soooo fine and it then just gets scattered into the castings? I don't know... are the worms still avoiding it on the micro-level? I don't know. My GUESS here is it must be broken down by microbes into mush before the worms can slurp it up... and being how its hard roasted beans, I'd imagine that can take many weeks to accomplish... longer if the grounds are coarse... hey, but that's just my own personal guess, with the truth being, I don't really know.

We save coffee grounds and just add it to the garden in spring and summer. We keep them in a bucket when on the road..

I usually get the bags starbucks throws out but Im noticing that in warmer months its harder to get those bags as more and more people are getting in on the coffee grounds. Yes good to add to gardens and rosebushes. Contrary to what a lot of people think the acidity is mostly washed out in the brewing process so dont hold back on that count. But in worm beds too much may heat the bin up, use caution.

I've heard that re: acidity, hummersteve, but then there's this:

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Now, on to coffee grounds! When we first started doing this show, we warned people to only spread coffee grounds around acid-loving plants, like azaleas, rhododendrons and blueberries, because the grounds were bound to be acidic; and not to overdo it on those and other flowering plants, as the grounds were certainly high in Nitrogen, which makes plants grow big, but can inhibit the numbers of flowers and fruits. 

But then we were sent some test results that showed grounds to be neutral on the pH scale! To find out what gives, I called Will Brinton, founder and Director of the Wood's End Research Laboratory in Maine, the definitive testers of soils, composts, and raw ingredients used in large-scale composting. Will solved the mystery instantly. Woods End, it turned out, was the source of that neutral test! Ah, but some follow-up investigation later revealed that it hadn'tbeen coffee grounds alone, as the person submitting the material for testing had stated, but grounds mixed with raw yard waste, the classic 'dry brown' material that is the heart of a good compost pile.


It turns out, as expected, that "coffee grounds alone are highly acidic," says Will, who saved all the grounds from his Lab's break room for a week recently just to test for us ("Eight o' 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 that's the most gentle result we've ever found," Will quickly added, explaining that the other 31 samples of raw coffee grounds they've tested over the years all had a pH below 5, too acidic for even some of the so-called acid loving plants.

"And in some ways, the grounds are even more acidic than those numbers imply", adds Will, who explains that the coffee grounds they've tested have also had a very high residual acidity; so high he recommends adding a cup of agricultural lime to every ten pounds of grounds BEFORE you add them to your compost pile. (High-quality hardwood ashes could be used instead of the lime, and would add more nutrients to the mix than the lime would.)

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http://www.gardensalive.com/product/using-coffee-grounds-correctly/you_bet_your_garden

OK you got me wondering on the ph of coffee grounds and Im not professional but I wanted to know where starbucks would test on my simple consumer test. I picked up a simple rapid test with color charts, on that I got a reading that is slightlyly acid at around 6.0. So to fine tune my reading a bit I just happened to have a digital readout Dr. Meter type from my hydroponic days . Using the same mix from the rapid ph test it settled out at 6.4. Now with either of those readings does not put me into any kind frightful scare of OMG I cant use that around my plants . The main issue Im thinking is to use it lightly just as I always have and when I put in my bins it gets mixed in with everything else. If this had testd at a mid to low 5 I would have concern so far it proves out pretty much in the range I talked about before.

Most garden veggies will grow just fine at 6.0. But out of curiosity did you use tap or distilled water?

De-chlorinated water.

Not sure IF it will make a diff. And I know you do like to experiment. I thought the idea was to use distilled water when using those home test kits?

True - where it says to add water it states preferably distilled in parenthees but I did not sort of skipped over that part . Im guessing the reason is to make sure there is no chlorine in it.

OK for the validity of my home test I ran the test again using Distilled water. This time I tried two different tests , one with my fresh brewed coffee grounds from this morning and again with starbucks. Test results showed the same and double checking with my digital dr meter at 6.0 nothing going below that. I see the tests showing that even at those readings most plants will not be harmed if sprinkled lightly around . For those still with concern dont use it or add a little garden lime to bring it back up.

Not the chlorine but to make some standard Ph for comparison. I am sure there are countless variations in water Ph thruout the country and this world.

I'm an organic vegetable gardener. I have read that the PH is 6.9 and that the grounds add a small mount of nitrogen. I've used about a ton of Starbucks coffee grounds and have experienced red wigglers invading bags of grounds and thriving in only them. I am convinced that the caffeine activates the reproductive urges to reproduce. I use the grounds both in my worm composting piles and in my soil to encourage the worms. I also pulverize eggshells which supply grit for their digestive systems and adds calcium to the soil especially for tomato plants to prevent blossom end rot on the earliest tomatoes.

When we were kids we added coffee grounds to our can of night crawlers.

Instead of grinding up eggshells I use sand. I have a bucket of eggshells circa 2000/2001. I crush & use (along with coarse sand) to keep slugs away from seedlings.

afaik eggshells do nothing for BER.

It takes forever for any eggshell calcium to get into plants even after pulverized., but I have been adding them to my worm bins for grit.

It maybe a bit OT but since BER was brought up I will mention that it is water that moves calcium from the soil thru the plant. And normally it is found that irregular watering which is the cause of BER and is esp. a problem in potted plants which tend to dry out sooner and more often.

There are many vodoo fixes for BER and it may depend IF the person or store giving the advice has a vested interest in selling you a product.

BER can affect many other veggies such as squash, peppers, cukes, pumpkin etc. Or anything which has a blossom. For more on BER you can check forums such as the tomato, veggie, soil, or container forums.

For grit for the worms I just use sand since that is what they get out in the real world. A little does go a looong waaaay, just sprinkle some on their food when you feed them.