Projects

Hypertufa mix:

3 parts peat moss, crumbled well with big sticks removed
2 parts Portland cement
1 part brown sand - not play sand
1 part vermiculite or perlite (more vermiculite for grey color, more perlite for lighter color in final product)
Handful of polypropelene fibers, separated as best as possible

In a wheelbarrow or other large container, mix ingredients well when dry. Add water gradually, small amounts toward end. You can add powdered concrete dye if desired. Goal is to get a heavy oatmeal-like texture that you can squeeze just a little water out of. Let sit 10 minutes while you prepare forms. Line forms with plastic if porous at all! Glad wrap is fine. Make folds as minimal and tight as possible.
Clean plastic molds well and they'll be fine as is. You can spray a vegetable oil to serve as a release instead of plastic wrap if molds are slightly porous. After filling forms, cover with plastic, leave in shade or a garage for three days. Uncover for two days. Remove from molds and let weather outside in shade for ten-twenty days before drilling drain holes and planting. After you take the molds off, you can use a wire brush to rough them up and a torch/candle to burn off any exposed fibers that might bother you. If you are doing this in freezing weather, the whole process needs to be done in a garage/basement that doesn't freeze.

Most any container will work as a mold. I've used plastic containers from the Dollar Store, rubber dishwashing pans, clay bowls-anything you like the shape of and that has some rigidity.