Most herbs used in cooking originate from the Mediterranean area so they grow in a gritty soil sort of like a cactus mix so they can dry out between waterings. They need sun and warmth, and perfect drainage to make good tasting leaves. So, the answer is, they need well draining soil.
I'm in Florida and have trouble keeping some herbs alive through our hot, humid summers. It's not the heat, but they really don't like the humidity so I'm not sure how well you'll do growing them in a paludarium.
