This is great! I'm wanting to make one of these as well and wondered if you considered making it hollow. In other words, I'm wondering if I could make it like a very large pot. So the top would be the part against the plywood and then you would place something in the middle to fill the empty space like you would if you were making a pot, still keeping the PVC pipe in there of course. I'm not sure yet what I'd use for the middle part, but I'm sure I can come up with something. The main reason I'm thinking of making it hollow is simply to make it easier for transporting. Any thoughts on that idea?

Some of my most primative pots have been made in a large pan/bowl. I rolled & twisted newspaper, taped it to the sides like spokes or however. Then put plastic as a mold release and packed the turfa on that. The turfa will reposition them to some degree. Take a look and it will be the one titled twisted newspaper. Keep in mind that the thickness will have to be thicker because of the space the newspaper is taking. Hum looks like I need to get some snow pictures moved. Here is a link that might be useful: Kathy's turfa

Depending on the size you can unmold in a few hours to 24/48 hours. If these are just plastic bowl molds unmold in 24 hours. Did you spray the plastic bowls with some kind of oil or use plastic bag for a release. Plastic bowls/tubs when brand new, will release without an oil but after that they are etched and it gets harder to get your mold to release. I don't use glass. Water seeping/rising to the surface is part of the curing process. After you unmold, immediately submerge mold in water and /or clean your molds right away. If not your cement mix will stick to your mold permanently. If you want a smooth side leave as it came from the mold and submerge in a bucket of water for a couple (read couple) of days. If you want a rough texture, gently scrub the sides with a wire brush or scotch-brite, rinse with water then submerge in a bucket of water for a couple of days. Change water each day. This flushes out the lime. You can plant in 5 to 7 days. There is no reason to wait 2 weeks, a month, several months to use these planters.

I love molds and have found the best are usually made of plastic. I usually cover them with one or more plastic bags to assure an easy release. When you're doing an outside mold on a bowl, it's important that you place mud all along the rim of the project, then plop on the center top, and work up from the rim. If the mud is too soupy, you might as well throw it back in the wheelbarrow and add some more dry ingredients. Just pat and firm the mud into place, and remember the weakest area tends to be right below the center rim. Mud has a tendency to slip downward, especially if too watery. You might want to add an extra layer of mud in this area just to make it a little stronger.