Orchids in a Terrarium

Lighting

• Lighting is critical to ensure the beautiful, prized blooms that orchids produce. If an orchid receives too little light, it won't be able to produce enough food to initiate a blooming cycle. Too much light can scorch the plant. Keep the terrarium out of direct sunlight, as this can cause the temperature within the enclosure to heat up too much, resulting in damage to your plants. Bright, indirect light is ideal. Add a white, reflective background to the tank to amplify the indirect light.

  Supplemental lighting also allows you to grow a wider range of orchids, not just the ones that thrive in low light. A standard aquarium hood fitted with fluorescent grow lights works well for this purpose

Watering

• Plants in a terrarium should never become waterlogged, because this causes the roots to rot. Make provisions for drainage in your terrarium. A layer of moss may act as a drainage layer in a small terrarium. Larger containers should have a drainage layer consisting of 1 to 3 inches of broken clay pots, charcoal, sand or gravel. Place a layer of sheet moss on top of these materials to prevent the soil from filtering down into the drainage layer. Place a layer of soil suitable for growing orchids on top of the moss.

  You can also decide to skip the soil and substrate altogether and simply place potted orchids on top of a plastic egg crate within the terrarium. If you do happen to overwater your terrarium, leave the cover off for several days until the excess moisture evaporates. The cover of a terrarium for orchids should never be airtight.

Temperature

• Typical in-home temperatures are OK for orchids. You may wish to place a thermometer into your terrarium to monitor the temperature when you first set it up. During the day, orchids usually enjoy temperatures between 65º F and 80º F. Lower temperatures at night are beneficial for some species. For example, Phalaenopsis orchids actually require cooler temperatures at night to initiate the blooming cycle. Evening temperatures of 55º F to 75º F are ideal.

Air Movement and Humidity

• Orchids are exposed to constant, gentle breezes in their native environments. Moving air is a crucial component in producing the showiest, healthiest plants. The U.S. Botanic Gardens suggests using a small fan within the terrarium, such as a computer fan. Small containers may not need any supplemental air circulation at all. Humidity in an average home hovers around 30 percent to 40 percent. A terrarium should help provide moist air for your orchid specimens, which usually thrive in humidity levels of 60 percent to 80 percent.

Ideal Species

• Orchids can get quite large -- some can grow 25 feet tall. Choose compact varieties, or select miniature orchids. Miniature orchids include Paphiopedilum (slipper orchids), miniature Phalaenopsis (moth orchids), and miniature Angraecum, Masdevallia, Pleurothallis, Promenaea, Dracula, Ornithocephalus, Aerangis, Bulbophyllum and Barbosella species. Keep in mind the scale of your terrarium when choosing your plants. You might want to add additional props to the terrarium, such as driftwood or rocks, to provide a background for the foliage and flowers.