When I add a new plant to my enclosure I take it outside and remove the root-ball from the pot. Gently WASH all the soil out of the root-ball. Don't remove it by hand as this will damage the roots, use the gentle stream of water to slowly erode all the soil away. Should take about 3 mins to do a 6" potted plant. Then I re-pot the plant in its original container with large diameter expanded clay pellets, instead of dirt, that were pre-soaked in 100% organic hydroponic fertilizer. As mentioned above it is a good idea to cover the top of the plant pot with large stones, or even put a stocking over the top of the pot so water can still get to the roots during your routine misting's.
I do this because I never get any dirt or run-off accumulated in the bottom of my cage. Since i have no dirt to clog things up and all my plants are embedded into the walls of my enclosure i put 3/8" tubes in the bottom of my pots so if there is any runoff to be collected after a misting it all drains back out of the enclosure instead of into the chams living space...
This is my first build so i would welcome and tips or concerns form our more experienced members if any of this isn't a good idea.