A growing medium: My favorite is plain old oatmeal. I've tried corn meal, cream of rice cereal, and mashed potatoes. They work, but not as nicely as oatmeal has for me. And besides, it is cheap. I'm told that hi-protein baby cereal works well, but usually stuff associated with feeding babies isn't cheap. Whatever the medium, it should be mixed with water to a pasty consistency. You want it to be very wet, but not watery. Oatmeal keeps soaking up water for a while so you may have to add more than you think to keep it wet. Keeping the proper dampness in the container is a big key to keeping them going. A trick that I've tried with mixed success is using a bit of vinegar in the medium to slightly acidify it. This is to inhibit mold. I've found that this is usually not necessary.