Dear All: I have been using the styrofoam boxes that grapes are packed in for some things. They are a bit shallow (about 4"), but the thick styrofoam insulates the potting soil really well. There are holes all around the periphery, so I have to drill a few holes down the middle. They're free!!! I usually only use them for sowing seeds, but some tiny bulbs do well in them too. When I lived in the hot Central Valley, they were outside in full sun, and the seedlings did extremely well in them. I put a torn piece of paper towel over the holes of pots. By the time it has rotted, the roots are filling the pot and holding the potting mix in place. Sometimes I do remove it by just pulling it through the hole. Drainage seems adequate. Diana Telos