Build Your Own Terrarium! – Due March 14, 2008 (Friday)

In this investigation you will be constructing a terrarium. A terrarium consists of one or more plants in a closed system. Central to how a terrarium works is transpiration (the loss of water from the leaves of a plant). In this process, tiny openings in the leaves release water vapor into the air. Water lost during transpiration is replaced by absorption of water by a plant’s roots. When a plant loses more water through transpiration than is absorbed through its roots, the plant wilts.

Materials Needed To Build Your Terrarium:

· Clear Plastic Container with cover (2-liter bottle)

· Soil – not dirt from a yard

· Pebbles – gravel, glass marbles, aquarium rocks, Styrofoam packaging peanuts

· Small plant – Do not use weeds, cacti, seeds or bulb plants. This should be a plant that you have purchased or a plant that you grow in your own garden. You must include the name of your plant (either with a garden stake or written on the outside of the container).

· Water

Procedure:

· Place a layer of pebbles about 3 cm deep in the bottom of your container.

· Put about 8 cm of moist soil in the container, on top of the pebbles.

· Slowly add water to the soil. Keep adding water until the soil feels moist, but not wet. DO NOT OVERWATER!!! You may see a little collect in the pebbles.

· Use a spoon to scoop out holes in the soil large enough for the plant root systems. Make sure the roots are completely submerged in the soil.

· Seal the terrarium completely (wide tape) and place it in a sunny area.

· Container must be completely sealed in order to create a closed system.

If you have properly created your terrarium, you should notice water collect on the walls of the container after just 4 hours in light. This water has transpired out of the plant leaves. It will fall down the sides of the container into the soil where it will be reabsorbed by the roots. Provided you did not put too much water in it (or too little), this plant can live for years without needing to be watered.