Make a closed terrarium by filling a container with rocks and potting soil, and then adding the plants. The plants themselves need to thrive in humid conditions and moist soil; choose moss and ferns, begonias or Moon Valley friendship plants. Avoid using succulents. Although they grow well on dishes or in open containers, the enclosed space and high humidity kills them.
First, choose a glass jar with a lid to serve as the terrarium. Choose the size of the container depending on the types and numbers of plants. For instance, Joseph's coat thrives in a closed terrarium, but it grows rather large, so either use a large container or transplant it after it reaches maximum height.
Next, add a drainage layer such as rocks and gravel to the bottom of a glass container to keep the soil from turning soggy. Because the container is clear, opt for decorative layers of brown and white rock with a sprinkle of charcoal on the top to better absorb moisture. Next, arrange the plants on top of the thin charcoal layer, and spoon well-drained potting soil around the roots for a thick layer. Add a whimsical touch to the terrarium by adding small animal figurines or colorful rocks.