So, You Want to Create a Terrarium?

Setting up and caring for a terrarium.

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Since there seems to be a growing interest in terrariums, here is information to get you started, or to help you improve the quality of your terrarium.

What is a terrarium?

A terrarium is a covered, enclosed, miniature landscape in which there is a living, growing, natural environment such as a garden, woodland, beach, marsh or even a Bermuda wall plant community. To create this landscape you need a glass or plastic container. You can buy this container, make it, or even recycle a glass or plastic jar for your terrarium.

Before setting up the terrarium

Some of the major concerns in creating and maintaining a terrarium are size, light, moisture and the type of plants to use to represent the habitat you are trying to recreate.

The size and shape of the container and opening will be important in several ways:

  1.  A larger terrarium with a large opening (for example a rectangular shape, perhaps an old aquarium) would be much easier to plant and maintain than a bottle with narrow opening.
  2. Every aspect creating and maintaining the terrarium, from installing the drainage and soil to pruning off dead leaves, will be easier with a larger opening.
  3. In addition, a container with a small opening would require special tools in order to plant and prune. The tools can easily be made but they do take some time and practice to master their use.
  4. A larger terrarium is easier to landscape and plant than a small one.
  5. Much more thought and attention must be given to what would fit and thrive in a small mayonnaise jar, for example, than a large container.
  6. A recommended size for a child’s terrarium is 12” long x 6” wide x 8” high.

Setting up your terrarium

Different sources of information will give slightly different, but still correct, methods for assembling a terrarium. This illustration shows a planted terrarium with layers of (A) potting mix, (B) charcoal, (C) drainage material. The additional layer of sphagnum or peat moss is recommended but considered optional. If used, the layer of moss should be placed between layers (B) and (C).

Different sources of information will give slightly different, but still correct, methods for assembling a terrarium. This illustration shows a planted terrarium with layers of (A) potting mix, (B) charcoal, (C) drainage material. The additional layer of sphagnum or peat moss is recommended but considered optional. If used, the layer of moss should be placed between layers (B) and (C).

  1. Choose a clean container.
  2. Depending on the size of your container, put in ¾” to 2” of drainage material which could be sand, gravel or small rocks.
  3. Cover this layer with a thin layer of sphagnum or peat moss to keep the soil out of the drainage material.
  4. Add charcoal chips. You can use cooking charcoal broken up into chips. (Do not use charcoal that has been pre-treated with lighter fluid.) For containers up to 1 gallon, use 3 or 4 heaped tablespoons.
  5. Next, add a layer of soil. Packaged soil or soil sterilized by baking is preferred since it will eliminate potential pests and diseases, unless you want to see what is in the soil, like what seeds will germinate, for example. Some peat moss and sand can be added to the soil to loosen it a bit.
  6. With the soil added, you are ready to create your landscape. Consider a slope or hill to create variety. Consider using a rock or driftwood as part of the design. Look around you at various habitats. Even a Bermuda wall may contain a small but varied landscape.

If you are using plants from the wild, don’t remove plants from protected areas (ie. nature reserves and parks, and don’t collect rare or endangered species).

Learn the names of the plants that you are using. Keep a simple diary about your terrarium.

Caring for your terrarium

Arrows follow the Rain Cycle process: from moisture in the ground, to water vapor in the air, back to moisture in the form of “rain drops” or condensation.

Arrows follow the Rain Cycle process: from moisture in the ground, to water vapor in the air, back to moisture in the form of “rain drops” or condensation.

  1. The terrarium will require indirect lighting. It will need plenty of light but no direct sunlight. Direct sunlight magnified by the glass of the container will quickly burn the plants.
  2. Moisture is essential. Soil should be moist but not soggy. Testing the soil with your finger should give you a fair idea of the moisture content.
  3. Once enough water has been introduced into the covered terrarium a RAIN CYCLE will develop. The plants take up water through their roots and pass it up through their stems and out through their leaves as water vapour. Soon the air becomes too wet (humid) to hold any more water vapour so water begins to condense on the top of the terrarium as drops (like rain). The water drops fall back to the soil to be taken up by the roots and the cycle starts again. 

 4. If the terrarium becomes completely clouded over with condensation it is too wet. It can be dried by using a paper towel. Too much water will cause the plants to rot. Most terrarium failures are due to too much moisture.

 5.If moisture does not condense at all, use a mister to increase the moisture content. If properly watered the terrarium should not need water for a while.

NOTE: If you plan to enter your terrarium in the Agricultural Exhibition, please check the Exhibition Catalogue (Dept of Parks) for details of size restrictions for containers, specific classes of entry etc.

There are several reference books on creating terrariums in the Natural History Library at the Bermuda Aquarium, Museum and Zoo. 

Call the BAMZ Librarian at 299 2329 ex 2125 to make an appointment.