Ficus elastica grow to be very tall and broad trees and the fastest growth will occur during the warmer months. When plants become root bound they tend to have stunted growth, wilt occurs very quickly and the leaves will turn yellow and drop. Tree roots naturally grow in an outward direction as they seek moisture and nutrients from the soil. With potted trees the roots will eventually fill the entire pot and there won't be much soil/compost left to take up the water and nutrients provided so the plant will succumb and die if not moved to a larger container. Depending on how quickly your plants grow you will have to move them up to larger size containers or you can keep them at a more optimum size by root pruning and replanting them in the same pots.
Rubber Plant (Ficus elastica)
Rubber Tree (Ficus elastica Chroma™ Abidjan)
Rubber Tree (Ficus elastica 'Tineke')
Prayer Plant (Maranta leuconeura) are slower growing, clumping plants of smaller stature, only growing to @ 12 inches tall and wide so they would do fine in smaller containers.
