You plant a terrarium by gathering the container and other materials, choosing the right plants, soaking the planting medium, adding materials to the container and setting the plants inside. After plants are set, you can accessorize to change the appearance of the terrarium.
In addition to the container, you will need plants, expanded clay pellets, Coir Brick and a fiberglass screen to plant your terrarium. You can use open or closed containers depending on the plants you decide to put in the terrarium. While closed containers are suited more for plants thriving in humid conditions, open containers are better for plants such as cactus that prefer dryer climates. The specific plant you choose typically depends on what will thrive in the area your terrarium will be placed.
Gardener's Supply Company recommends using Coir Bricks as the medium for your plants. Soak it in a bucket of warm water for 30 minutes, and use a trowel to break it up as it's expanding. Next, place 2 inches of expanding clay pellets on the bottom of the container. Size and cut some fiberglass to cover the pellets inside the container. If the container is deep enough, add 2 or 3 inches of the coir on top of the screen. Now, arrange plants and accessories to complete the terrarium.