The worms help break down any of the leaves and organic matter that is put in the compost pile or in the various garden beds. When I first moved here, there were virtually zero earth worms in the dry sandy soil. Now, when moving most any container, earthworms will be in and under it. It is my understanding that the presence of earthworms is a great indication of the health of your soil. Also, worm castings are supposed to be a tremendous source of nutrients for plants. Further, the digging and tunneling of the worms is a great aerator for the soil.
WRT oak leaves being acid, I was curious about that in the past and did a good bit of googling and found several bits of research, all of which indicated that the acid nature of oak leaves is a myth, that composted oak leaves tend to be very near neutral. Here is a typical quote related to oak leaf acidity: "[myth]You can't use oak leaves on your garden because they're too acid. [fact]False. As oak leaves rot they lose their slight acidity, and the oak leaf mold ends up alkaline."
I am sure that you could establish a worm bed, but if using something like my kettle grill, it may have to be in a sheltered location during really cold freezes. I did leave mine outside as temperatures visited the single digits for a couple of days. The worms seem no worse for wear from exposure to those temperatures. If you don't have a sheltered location, like a closed garage, it probably would be better for you to make a more coventional worm bed that is in contact with the ground, that would allow the worms to dig deeper when the soil temperature drops really low. One main reason for my using the kettle grill is to discourage fireants from decimating the worm population. If not for that, I would have just continued growing my worms in the open compost pile. The worms did great in my compost pile until the invading fire ants moved in, eating the worms and anything that moved, in fact most everything else as well. Here is a repost regarding the re-use of my old kettle grill.
This original post was first listed under the thread "trash to treasure" on the Non-Gardening Related Hoo-ha and Foo board.
As you know, have been following this trash to treasure thread. Well, there was another thread over on the compost board, mentioned a worm bed. So happens I have a pretty good compost pile and at least 20 years ago added a pound or two or earth worms. Up until a couple of years ago when the fire ants invaded the compost piles I would have huge masses of worms throughout the pile. It never occurred to me to consider a worm bed. So with the post related to a worm bed, and then this thread on re-use, my mind started turning, [what can I use for a worm bed.] Just happened to think about a large kettle grill that got replaced by a fancy gas unit and has been stored in the barn for at least ten years. It has vent holes for air, a lid to keep out undesireable critters and is heavy enamel and aluminum. So the experiment begins. Half filled the kettle grill with partially decomposed compost, sifted through and picked out some earthworms to make sure a few were in this starter mix. In the future rather than adding my kitchen scraps directly to the compost pile, instead will put them in this makeshift worm bed. Will let you know how it works.
The grill was converted to a worm bed in July of 2008. I added about 40 additional worms gathered from my daughters home in N.C. Since that time I've pulled out perhaps a quarter pound of worms and introduced them to several raised beds and to two compost piles. Just sifting though the mix in the kettle gives me the impressiion that there are now thousands of earth worms in that compost/kitchen waste mix. The worms are really thriving and it is here in mid winter. In the spring I would expect an explosion of the earthworms to add to our landscape.
So far the kettle drum is a perfect worm bed. It is small enough for easy management. It is easily transportable. It is resistant to corrosion. It has the capacity to grow many thousands of earthworms. It has air holes for circulation, a lid to keep out undesireable critters. I even keep a bucket under the grill to catch any liquids that pass through, will dump that into my various raised beds. The only management is adding kitchen scraps once or twice per month, and also turning with a hand gardening fork about once per week.