With cool weather setting in and Old Man Winter coming upon us, a tropical paradise will help brighten an indoor room and combat the winter blues. One way to create a tropical oasis in the middle of winter is to build a terrarium. Terrariums are closed glass or transparent plastic containers used to create a 'mini environment' for plants. The principle behind a terrarium is simple. The water from the soil is taken up into the plant as it grows. The water is then released through the leaves via transpiration. This water condenses on the glass and runs back to the soil where it can be used again. Because this mini water cycle occurs inside the sealed terrarium, the plants can go for months without watering. It also creates a jungle-like atmosphere of high humidity, warm temperatures and no drafts, which are perfect conditions for many of the tropic-native houseplants common today.

Rooted in the Victorian Age

The history of terrariums is rooted in the Victorian age. They were used in parlors to house many delicate and exotic plants. Despite the fact terrariums have been around for many years, they have never returned to the popularity of 1850's. Constructing a terrarium is easy, inexpensive and can be accomplished in a snowy afternoon. Suitable containers can be found in most homes. Their care is minimal since they can go for months without water under the proper conditions. In addition, a wide variety of plants can be grown that would normally fail miserably in the dry, drafty environment of the average home.

Getting Started

Assembling and planting a terrarium is easy. Start with a clean, dry container. Terrariums or glass cases can be purchased at many stores, but an old 10-gallon fish tank, a large glass jar, or a large glass bowl with a beveled glass lid could work just as well. Since terrariums don't have drainage holes, place a 2-inch layer of gravel, pebbles or perlite on the bottom of the container to insure good drainage. Next add a one-fourth inch layer of charcoal. The charcoal aids drainage and helps control soil odors. Finally, add one to four inches of light, well-drained potting soil. As you are adding the soil, create hills and valleys to add interest.

Choosing the Perfect Plants

The next step is selecting your plants. Plants with slow growth rates, tolerance of high humidity and small leaves make good candidates for terrariums. A general rule of thumb when designing a terrarium is to choose an upright growing plant, a trailing plant and a plant of intermediate size. A terrarium is not the place for philodendron and spider plant. Instead, use this special environment to grow plants that are exotic and could not live on your windowsill, such as net plant, creeping moss and ferns. Flowering plants such as miniature African violets and carnivorous plants such as pitcher plants and venus fly traps make beautiful and fun additions to terrariums. In fact, the humid environment is good for any houseplant except cacti and succulents, which suffer in a humid environment.

Planting and Finishing Touches

To plant a terrarium, simply remove the plant from the pot, gently shake off excess soil and place in the soil inside the terrarium. Rocks and stones make good additions to your miniature landscape. Small shells, small figures, toy dinosaurs or other similar items can also be added for a touch of fun. The options are limited only by your imagination; just remember not to incorporate wood. Sometimes, driftwood or similar wood products could introduce unwanted insects and fungi, which will thrive in a terrarium's humid environment.

Watering and Care

To finish your terrarium, moisten the soil by misting heavily or using a rubber bulb sprinkler. Soil stuck to the glass from planting can be rinsed off by lightly running water down the glass. After watering, cover with a piece of beveled glass or saran wrap. Place the terrarium in medium to bright, indirect sunlight. An east or north window would be a good choice. Fertilizer should not be used, because it will encourage growth and earlier crowding of the plants. If excessive condensation builds up on the glass, uncover the terrarium until some of the condensation evaporates; then replace the cover. Enjoy!

Plants for Terrariums

Upright / Tall Plants

Mid-size Plants

Low / Trailing Plants

This article originally appeared in the January 18, 2002 issue, pp. 3-4.