A terrarium is a miniature enclosed ecosystem that can add interest to a desk, shelf, or tabletop. Creating a terrarium isn’t difficult and can be an enjoyable hobby that will allow you to use your creativity and gardening skills. Closed terrariums are sealed, creating a warm, humid environment for the growing plants. An open terrarium is easier to maintain and the plants are less susceptible to disease, making open terrariums a suitable choice for beginners. Open terrariums can make a fun option for cacti and succulent gardens as well as tillandsias.
1. Nearly any container will work, although containers with large openings are easiest to plant for beginners. Possible container options include fish tanks, goldfish bowls, brandy snifters, or large glass jars. Wash old or pre-used containers with a mixture of hot water and a few drops of liquid dish detergent, then rise thoroughly.
2. Select plants for your terrarium. For best results, choose healthy, compact plants that have similar light and moisture requirements. Although nearly any small houseplant can be used in a terrarium, a few recommended choices include begonias, spider plants, African violets, miniature ferns, baby tears, coleus, English ivy, haworthia, Spike moss, and oxalis.
3. Provide drainage by placing a thin layer of small, clean gravel or pebbles on the bottom of the container. Cover the pebbles with a 1/2 inch layer of activated charcoal which will eliminate toxins and provide fresh air in your terrarium.
4. Layer 2–3 inches of potting soil on top of the activated charcoal. Any good quality, well-drained potting soil will work. If you intend to plant a cactus terrarium, use a cactus/succulent potting soil.
5. Use your fingers to make a small hole for each plant, then place the plant in the hole. Tamp the potting soil gently around the roots.
6. Spray down the sides of the container with a spray bottle to clean off excess soil. Moisten the potting soil by sprinkling water on the soil. Don’t water excessively, as most house plants will rot in soggy soil. Sprinkle water in your terrarium whenever the soil becomes dry.
7. Add decorative elements such as rocks, seashells, small pieces of wood, or ceramic figures to your terrarium. Make sure to wash these items with soap and water before placing in closed terrariums. Or, if you prefer simplicity, leave your terrarium as it is.
8. Place your terrarium in indirect sunlight. Don’t place the terrarium on a windowsill, as the light magnified through the glass may be hot enough to scorch the plants.