What kind of plants and snails? IME, it is easy to accidently put in a snail prone to multiplying out of control and if that happens, you could end up with serious bioload and water quality issues. I imagine you are talking about a snail that does not reproduce asexually. With plants, if the plants start out poorly on a small scale that can cause more problems than not having plants at all, so I imagine you are talking about plants such as duckweed, java moss, java ferns, etc., that are not as nit picky about water conditions and light.
I'm talking about plants in general, Swords, HC, HM, Java Fern, Occasionally mosses, an assortment of stems and so on. You know the kind of plants that go into Aquariums? And snails, Pond, Ram, MTS. Again the types usually found in aquariums.
As for light and water conditions, these vases are not kept in a dark closet on a back shelf. They are kept right out where my other aquariums are kept. They get light from various sources and I change water when needed, feed them and watch to see what is working and what is not and try to determine what I've done right and what wrong so this info can be applied to other tanks and situations. I watch bioloads and if there are to many snails in a Vase/Bowl I remove some, If something should die I remove it promptly. You know, Kind of like taking care of a squareish type tank.
I would now like to apologize to Jason for side tracking this thread and suggest any further communications be started in a new thread or PM me. Thanks