I'm planning to sell small pots and as part of my display I'd like to "plant" fake plants in some of them. I'd like it to look as real as possible, so my goal is to have the plant "growing" out of a solid block of what looks like soil. I'd like to be able to grab the plant and lift it out along with the attached soil bottom then plunk the whole thing into a new pot as I sell them.
I'm not sure exactly how to make the dirt bulb for the plant. I was thinking of molding it by pouring something granular (granulated + dyed cork maybe?) and glue or resin into a sacrificial Tupperware of similar size to my pots, sticking the plant in and letting it dry. The only thing I'm worried about is making sure the whole things stays in shape without crumbling once it's out of the Tupperware. Any suggestions on fake dirt materials and/or glues to use?