Here is my worm hotel. I started with just a couple little tubs of red wigglers from the pet store, and now I have about 4584953 worms. I use coco fiber as bedding, with a little bit of soil mixed in. You don't want to put them in dirt alone, but you need a little bit mixed with the bedding because the grit helps them digest their food. I ordered a big 4 pound block of it, and that's enough to last a pretty long time. You just break a chunk off the block and soak it in water, and it swells up to 390584 times its original size. The trays in the bin are perforated on the bottom, and the worms work their way up to the top. When the food in the bottom tray is gone, you change out part of the bedding, throwing the old stuff on your plants, and move the tray back up to the top and put in more food. I feed them fruit and veggie kitchen scraps, and sometimes ground up eggshell. The eggshell helps to add extra grit, and it also helps keep the pH from becoming too acidic. You don't want to add anything really strong or spicy, no hot peppers or onions or citrus fruit or anything like that. They seem to really like tomatoes, every time I put a piece of tomato in, I find a swarm of worms right underneath it within a day. I shoot the top of each layer with a spray bottle if it starts to look a little dry, but you don't want to overdo it. You want to keep it just barely moist, but not soggy.
You might encounter little tiny white spheres the size of a pinhead after your bin has been set up awhile. I first thought these were worm eggs, but it turns out they are mites. Actual worm cocoons look like brown popcorn kernels. The mites are a nuisance, but they don't harm the worms directly, although they can start to outcompete them for food if you let them get out of control. The mites are a sign that you are keeping your bin too moist. They seem to like sugary foods, like apples and banana peels. The way I combat them is to sprinkle a layer of really dry bedding on top of the food if I add alot of really moist sugary stuff. The worms can still get to the food from below, but it seems to make it harder for the mites. Then I place a slice of apple or something similar out in the open in the top tray, and let the mites collect on it, and just throw them away. You'll never completely eliminate them once you have them, but they're not a big deal to keep under control.
A worm farm is a great way to reduce your trash output, make fertilizer for your plants, and raise some fish food. And it pretty much takes care of itself once it's established.
