Select compatible plants for the terrarium. Miniature orchids, small anthuriums, filmy ferns, small gesneriads, and dwarf rex begonias all thrive under the same humid, filtered-light conditions. As a rule, it is a mistake to include rampant-growing plants in these small gardens. I make an exception to this sometimes with newly rooted cuttings of coleus, artillery-fern (Pilea microphylla), and other plants which can be cut back severely, as necessary, without harm.

   Cacti and other succulents of all kinds can be planted together, in an open-topped terrarium. A similar planter makes a good showcase for a collection of small rosette- or star-shaped brome-liads like Cryptanthus acaulis with its wavy green leaves, and its striped variety, zebrinus.

   When planting a woodland scene, carpet the bottom of the terrarium with moss and lichen-covered wood found in the woods. If you can't take a stroll in the woods, purchase some green sheet moss and use it for ground cover.

   A number of small creeping plants will also provide suitable ground covering: mossy-leaved selaginella, hairy-leaved Pilea repens, and cup-leaved P. depressa, for example. Bronze and chartreuse Pellioma daveauana or gray-blue P. pulchra lend interesting form and color. For fragrance, plant the smallest of mints, lavender-flowered Mentha requienii. Baby's-tears (Helxine soleirolii) with its round, apple-green leaves is a rampant, easily cultivated terrarium creeper.

   Inside a terrarium, or in a dish garden, you'll find these creepers have many decorative uses. One terrarium might be planted entirely of creepers by building terraces at different levels so they can creep, cascade, and show off. They can be made to swing down a small-scaled wall, or creep up a soft piece of rotted bark. They'll carpet the soil around and between larger, upright plants. One of the smallest can border a small "pool," and appear to dip some of its leaves delicately into the water.

   Before planting a bottle garden, remove smears or smudges inside the bottle by spraying the inside with a window-cleaning spray. Let it remain inside a minute, then wipe it off using a lintless cloth on a bent stick or wire. Do not fill the bottle the same day you have used the cleaning spray, for the fumes might harm sensitive plants.