How to Build a Natural Terrarium Background

Measure the inside height and width of the terrarium back wall.

With the jigsaw, cut the plywood sheet to the exact dimensions of the terrarium back wall. The sheet will serve as the base for your terrarium background.

Lay out some newspaper as a work space. It should be larger than your plywood sheet to catch any over spray. Place the plywood sheet atop the newspaper.

Spray the plywood sheet with polyurethane wood sealant, and let it sit 24 hours. This will prevent the wood from absorbing too much moisture and getting mold or mildew. Having a waterproof background is particularly important in a terrarium with animals such as chameleons or tree frogs that require high humidity.

Apply the insulating foam to the plywood. It will come out as a white foam and will serve as the "rocks wall" of your background. Cover the entire sheet of plywood with the foam and layer it so it simulates different rocky features.

Sprinkle coconut husk, peat, reptile bark or cob onto the insulating foam while it is still wet. This will create a natural aesthetic. Cover the entire surface with the substrate of your choice or a mixture of all of them. Alternatively, paint the foam a natural color such as brown, gray or green for a simpler look. Allow 48 hours for the foam to harden.

Slip the newly created background onto the back wall of the terrarium. Seal it in place along the edges with aquarium-safe silicone sealant for a tight, secure fit.