Clean out or purchase a new glass container to use for your terrarium. Terrariums can be made from a variety of containers with wide mouths, such as fish bowls, candy jars, and even mason jars. If you're reusing a glass container or jar, make sure it is clean and free from dirt and debris.
Cover the bottom of your glass container with 2 inches of gravel.
Place a thin layer of sheet moss face down on top of the gravel.
Add 1 inch of soil on top of the sheet moss. If you want to plant both small and larger plants in the terrarium, you may want to build up the soil more than 1 inch in the area where you will place the larger plant, because large plants need deeper soil. For example, in front of the terrarium, you may have a 1-inch layer of soil, and in the back you may have a 2-inch layer of soil, so it looks like a small incline inside the terrarium.
Mist the terrarium with a spray bottle after you have planted seeds or seedlings. Once you see the water beginning to seep through the moss, stop misting.
Cover the terrarium with a glass cover or plastic wrap secured with a rubber band. Keep the cover secure, because it will maintain the humidity in the terrarium.
Keep your terrarium in a room with indirect sunlight.