Tammy Algood of the University of Tennessee Agricultural Extension Service explains how to plant an easy-care tabletop terrarium. A terrarium is nothing more than a miniature self-contained greenhouse, and you can create your own from any type of covered glass container. The key to successful terrarium culture is keeping the lid on to maintain the humidity. Once the terrarium has been planted, the humidity inside the jar will keep plants moist, so they require very little care. The cover can be made from a lid that came with a container, a stone or a sheet of plastic.
Unused aquariums make great terrariums, and plastic works as well as glass.
Whatever the container, a tight-fitting top is crucial. A successful terrarium must have adequate drainage, with a layer of material under the soil to prevent the roots from standing in water. African violets, hypoestes, ivy, ferns and other moisture-loving indoor plants make good choices for a terrarium planting. Within a year or two, all plants will eventually outgrow the terrarium environment and need to be transplanted. Miniature varieties can remain in the terrarium a little longer.