Terrarium gardening — a method of growing plants in a glass container — is a ideal way to repurpose a used aquarium, since the closed environment creates humid, greenhouse-like conditions valuable for tropical plants. Although developing a terrarium isn’t difficult, specialized techniques are expected to maintain the plants healthy.
Scrub the aquarium thoroughly with liquid dish detergent and warm water.
Scatter 1 to 3 inches of gravel or pebbles in the bottom of the aquarium. The coarse material provides drainage.
Sprinkle a thin layer of activated charcoal over the seams to keep the environment fresh. Use approximately 2 to 4 tablespoons of charcoal, depending on the size of the aquarium.
Cover the charcoal with a layer of sphagnum moss. Arrange the moss with the mossy side facing prevent potting soil from dropping into the gravel.
Spread 1/2 to 1 inch of potting mixture over the moss. Use a potting mixture consisting of 2 parts lightweight commercial potting mixture and one part coarse sand.
Purchase small, tropical plants in a number of colours, shapes and textures. Arrange the plants before planting, and then return to view the entire effect. Rearrange the plants until you are satisfied. Place taller plants in the rear and smaller plants in the front. If the aquarium is viewed from all angles, then place the tall plants in the center, surrounded by smaller plants.
Put the plants in the potting mixture one at a time. Use your fingers to produce a small hole for the roots. Place the plant in the hole, and then pat on the potting mix gently around the roots.
Add decorative items such as figurines, driftwood or colorful stones, if wanted. Avoid items covered with paint or artificial coloring.
Spray the plants with a fine mist, supplying just enough water to soften the soil and foliage.
Set the terrarium in indirect sunlight.
Spray the inside of the terrarium approximately once every month, or at the very top of the mixture feels dry.