Orchids and Day Geckos?

[Cassia]

I am being given a 75-gallon aquarium, and I am hoping to create a vivarium with day geckos and orchids (and a few other plants, such as maidenhair fern). I have never kept geckos, so I'll be starting with the beginner's Phelsuma laticauda laticauda. I have a few orchids in my kitchen garden window over gravel trays. Some of them are not very happy, so I'm hoping to move them into the vivarium. I read the sticky on appropriate plants, and will work with that as a basis.

However--can I plant orchids directly into soil or other substrate in the vivarium, or do they need to be in pots?

I'm so new at this that I don't even know all the right questions to ask. So---ANY help or tips will be very much appreciated!