Wash the glass cookie jar with hot water and soap. Rinse the jar thoroughly and dry it. This helps kill bacteria that may be harmful to your plants.
Lay an even layer of clean gravel on the bottom of the jar, about 1 inch deep to provide drainage.
Scatter 2 tablespoons of activated charcoal evenly over the gravel to keep the rainforest air smelling fresh.
Put potting soil over the activated charcoal, making an even layer. Don’t add soil to the top 3/4 of the jar.
Remove the plants from their containers, and arrange them on the counter, to decide how best to position them. Take care not to disturb the roots too much. Good plants for a rainforest terrarium might include philodendrons or pothos.
Plant each plant in the soil, one at a time. Use your hand to make a small indentation in the soil before setting the roots in the indentation and covering the roots with soil. Pat the soil gently to firm it up.
Spray the inside walls of the cookie jar with water to remove any excess dirt and irrigate the soil. Do not over water the soil. It should be moist, not wet.
Place the container in indirect sunshine. Cover it with the lid.