Building a Terrarium

Let's build on what we have learnt from the Community Helpers box! Let's continue to be little gardeners by building a terrarium at home.

A terrarium is a miniature garden grown inside a covered glass or plastic container. You will not have to water the plants in this self-sustainable system. In fact, the terrarium you see here was set up 1 year ago!

You will need:

1) An enclosed glass or plastic container (preferably with a big opening)

2) pea gravel or small rocks

3) Potting soil

4) Small and slow-growing indoor plants ( such as African violet, artillery fern, spider plant, strawberry begonia etc)

5) Filtering charcoal (optional)

Step by Step

1) Clean your container with soap and water. Rinse well and dry thoroughly.

2) Cover the bottom of the container with about 2 to 3 cm of pea gravel/small rocks for drainage. 

3) Add a layer of filtering charcoal (optional) to remove any odour.

4) Estimate the amount of soil needed to fill up to one-third of the container with moist potting mix. Pour the soil into a bowl or tub and mix with water until the soil is moist enough to roll into a small ball. If water drips from the soil when it is pressed into a ball, it is too wet. Add more dry potting soil. Once the soil is nicely moist, place the soil in the container. 

5) Add your plants. Include any decorative objects such as small animal figurines. 

After planting, cover your container with the lid. Place the terrarium somewhere with indirect sunlight. Observe your terrarium for the first few days - the sides and top will get misty with water droplets when in bright light. If you do not see any moisture, you need to add more water. If the sides are always wet, there is too much water. You should remove the lid and allow some water to evaporate. 


We can see the water cycle in action in your terrarium! In the presence of light and heat, water evaporates from the plants through transpiration and from the soil. Because the lid is closed, the water vapour hits the side of the container and it condenses. Once enough water accumulates or the temperature decreases, the condensation will then precipitate down the sides of the container back into the soil.

Besides water, air is also recycled in the terrarium. The plants absorb carbon dioxide in the day to make food. It gives out oxygen at night for use in the day and the cycle continues.