Lol, this kind of reminds me of a debate on another forum concerning feeding ball pythons on substrate versus paper towels or newspaper... one member commented, "south africa is not covered in paper towels".
Many folks bake cage decor taken from nature, others use a 10 parts water to 1 part bleach spray, others dust it off and put it in the enclosure. I think it's a matter of common sense and experience. If the item you're placing in the tank is clean and healthy, it'll probably be fine. If it's questionable, like you don't know the conditions the plant is in all the time - do the neighborhood cats and dogs use it for a litter box for example, then it'd be best to get a start of it from the garden store and make sure it's chemical free. That's my humble opinion
