The spring time is when the grounds are most in demand. Maybe let them have them then and you take them in the off season. I find that after the pumpkins it is slim pickings during the winter. That is when I would most want the grounds. But then again if I had unlimited supply of grounds I would probably not put them in my bin. I would spread them around the lawn in a very thin layer. Or grow mushrooms with them. I too am not convinced the worms do anything with the grounds. It would seem to be good just to let the grounds hang out in the bin and gain wee beasties and harvest them back out giving bulk to the castings.

It has been my experience that worms are not fond of fresh grounds, but after they grow a white fungus on them, the worms will feast on them. Coffee grounds don't like to hold moisture. When they dry out, they can form a hard crust. After growing the fungus, that all changes.

The particles in UCG are still too big for worms to take in. I agree w. sbryce, since the worms take in the MO growing on the UCG. IMO it also takes a long time for coffee to break down and with the dark colour, after a time, you can't really tell if the UCG have decomposed or just blended in the VC. The SB's goes to my backyard composter, every now & then I added the home brew UCG to the wormbin.

nostting: ask your friend to save the banana peels for you, let the older woman have all the UCG, lol.

I use a lot of coffee grounds in my worm bin and it took me a while to figure out how to tell them from worm poop. My first method is texture. If you rub some castings between your fingers (even with gloves) and it feels grainy, it's not worm poop yet. Another is to dissolve it in water. The castings dissolve completely but the grounds of course do not. Since I usually dissolve the castings in water before I apply it to my plants, when I am done I can see at the bottom of the bucket if there are any grounds. It may seem surprising, but usually there aren't. If there are any, it is only a few.

I've been doing this for many years and so now I can tell when the castings are done pretty well just by looking. In my experience grounds get processed at about the same speed as other food. In general, when there aren't remnants of more distinctly visible food, then there aren't remnants of coffee grounds, either. I keep new and old food separated in the bin, however. YMMV.

Yeah, the biggest trick I find with grounds is keeping them moist. As I don't have a huge amount of them, I can mix them into my other foods (as I do with my bread). Seems to help keep them wet and avoid the coffee cakes you can get.

I don't worry about weather the worms are digesting the coffee grounds since the grounds are an excellent addition to the spent media which I use for germination and potting mixes. Coffee ground's low nitrogen value are an excellent addition to the vermicompost I use for gardening. I figure if the worms get some food value from the addition of the grounds, all the better.

As Sbryce mentions allowing the grounds to mold before feed them to the worms helps the worms to digest the grounds. But, this is also true of other foods as well. I use large plastic mayo jars to deposit the coffee grounds. Leaving them covered in a warm place will expedited the formation of mold.

I do the same thing with veggie scraps. I place the scraps in a 5-gallon bucket and add enough water to cover the scraps. Using a Dollar General pair of kitchen gloves I extract several large handfuls of these fermented scraps and place them in a blender with an equal volume of water. Just make sure you replace the lid on the bucket, or you might end up with some interesting critters best left outside. If that does happen, dump the bucket in your outside compost pile and start anew.