you made the right choice in starting with less plants. as brian said, many people forget that they are buying young plants and they will grow. especially ferns. some can grow monstrous, but can be controlled with some regular pruning. remember that red eyes live high in the trees, so plan your plantings around that. if you want a nice, sturdy plant for the ground that a lot of people over look, pick up a diffenbachia. it will grow to be a giant, but with regular pruning, it can be controlled. in a tree frog environment, especially a species such as a red eye, the ground layer is for you. the aerial space is for the frogs. at least that is the way i always look at it. just like brian said, some nice pothos or any of the climbing philodendrons will work wonderfully. remember as far as the philos. go, there are terrestrial species and well as vine species. also keep in mind that with heavy planting in the upper portions of the enclosure, your ground plants need to be shade loving plants. light loving plants will grow, but very slowly.