Well the first time I made it, it didn't set up as well.
The recipe calls for 2 cups of liquid potpourri and 4 packs of unflavored gelatin. Heat up 1 cup of the potpourri, mix in the gelatin til dissolved, then add the other cup of potpourri and pour into jars. They were liquidy on top for the first week until they started to evaporate.
But now I just bought a whole bunch of the water absorbing crystals and I've been using those. They say to add 2 Tbs of vodka to keep it from molding while sitting out.