A terrarium is a miniature ecosystem. This project will demonstrate how the earth is a closed system and recycles air, water, and other elements in a continuous loop.
You Will Need:
One clear 2-liter soda bottle
Phillips head screwdriver
Activated charcoal, available at garden or pet supply stores
Small plants (Note: Only certain kinds of plants will thrive in the terrarium's moist environment. Try using mosses, very small ferns, or miniature African Violets)
Constructing the Terrarium
- Remove the colored base of the bottle.
- Cut off the top of the bottle, about 1/4 of the way down.
- Turn the clear, round part of the bottle upside down and punch four (4) holes into the round end. Use the hammer and screwdriver, punching the hole from inside out. These will be the ventilation holes.
- Fit the clear part into the base cap. You may need to slit the clear part and squeeze it together to fit it inside the base.
Planting the Terrarium
- Put about 1/4 inch of pebbles in the bottom of the base cap.
- Cover the pebbles with a 1/4 inch layer of charcoal.
- Cover the charcoal with 2 inches of soil. The soil should be slightly damp. Set your plants into the soil, pressing the soil gently around the roots.
- Spray or sprinkle your plants with water, then cover them with the clear top.
- Set your terrarium in indirect light, such as a north or northwest window.
Some helpful hints:
Many terrariums last indefinitely, demonstrating a balanced ecosystem. However, if mold or mildew should appear, leave the clear top off for a few days. The mildew grows because of too much moisture, and letting it dry out a little will help.
Use plants that grow slowly, or prune them as they outgrow your containers. Add interesting rocks or bits of bark with lichen or moss. Use your imagination!
After building this small terrarium, try building a larger one in a fish tank. They are often easier to maintain. One or two small animals like snails, salamanders, and insects can be added to larger set-ups.
Closing the ventilation holes will make it a truly closed system. The water that collects on the inside of your bottle demonstrates nature's water cycle. Larger holes will ventilate it more so you can see inside better, but you'll have to check to make sure the terrarium doesn't dry out.
This project was developed by the Museum of Science & Industry, Tampa and
The City of Tampa Solid Waste Department.
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