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.
Here's how to plant your own terrarium. Mix a sterile growing medium made from potting soil, peat moss, sand and perlite. Add a slow-release fertilizer to the mix. Pour the soil into the terrarium. If the opening is small, make a funnel of rolled newspaper to keep the sides of the glass clean.