A plant terrarium is a man-made ecosystem where a collection of plant life grows in its own small world. Depending on the design of the container, some terrariums are self-watering, in that the water cycle of evaporation and precipitation takes place inside the container, with minimal intervention from the terrarium's caretaker.
Typically, the terrarium container is made of transparent material, such as plastic or glass. The first creative decision in making a terrarium is selecting the container. Make a terrarium from a small goldfish bowl, or a larger fish aquarium. Recycle glass or plastic jars. Decorative glass containers, such as apothecary jars or glass cookie jars, make suitable terrarium containers. Make boxes from sheets of glass or plastic. Large empty water jugs, set on their side, make suitable containers, yet are more challenging to fill. Convert a potted plant into a terrarium of sorts by placing a glass or plastic dome over the container.
Before assembling the terrarium, decide on a theme, which will influence what plants you select and what embellishments you add. Standard terrarium themes include beach, jungle or desert. But there are others to consider, such as one with a national flavor, or a holiday theme. Assembling a terrarium is akin to creating a small world; use your imagination when designing the space.
Part of the fun in making a terrarium is adding small embellishments. Take a trip to the craft store to get ideas and purchase appropriate decorations, or look for interesting items when browsing thrift shops or garage sales. A suitable ornament might be miniature porcelain or glass animal such as a frog or turtle. Use tiny bridges, ships and figurines in decorating terrariums. You do not need to buy embellishments--nature offers suitable options. Decorate the terrarium landscape by adding moss, interesting rocks or shells.
Some terrariums double as a habitat for a living creature, such as a reptile. Terrariums have been homes to spiders, frogs, snails, lizards, turtles and snakes. A terrarium habitat will require a bit more care in developing and maintaining if it is to provide a humane home for a living creature. The container needs to be large enough, and enclosed to prevent the creature from wandering off.