Thanks to a sealed environment that traps moisture but lets in light, this self-contained mini greenhouse needs little care.
Place a 1- to 2-inch layer of the gravel in the container, then sprinkle on a thin layer of the activated charcoal. Top this with a layer (from 2 inches to as much as one fourth of the height of the terrarium) of potting soil.
To add the plants, first scoop out holes for planting, then take the plants from their pots and carefully remove any excess soil from their roots. Set the plants in their holes, then gently pack the soil around each one. Lightly mist the plants with a spray bottle.
Replace the jar's lid and set the rain forest in a bright spot away from direct sunlight. Your indoor garden may never need watering, but check it every few weeks and add more water by lightly spritzing the plants with the spray bottle if the soil feels dry. If heavy condensation forms inside the glass, temporarily lift the cover to let some of the moisture escape.