3. Layer your materials.
Much like a lasagna, building a terrarium requires you to layer certain materials to ensure that the plants will get the proper moisture and that water will drain correctly.
Layer 1 (bottom): Pebbles or stones to allow for drainage.
Layer 2: Activated charcoal on top of the stones to keep mold from developing in the terrarium.
Layer 3: An inch or two of potting soil.
Layer 4: Your plants—make sure they all have the same light and moisture requirements.
Layer 5 (top): Decorative elements like stones, figurines, or other inanimate objects. This section is optional and purely for aesthetic purposes.