What is a Terrarium?
A terrarium is a collection of small plants growing in a transparent, sealed container. A terrarium
is a closed environment, and can actually be used to illustrate how an ecosystem works. Inside a
terrarium’s walls, many different natural processes may be observed: photosynthesis, respiration,
and the water cycle. The water in the terrarium is constantly recycled, passing from liquid form to
gas and back again. As the moisture in the air condenses on the glass walls, it returns to the soil
and is absorbed by the plants’ roots.
Clear glass or plastic container
Activated charcoal (from aquarium or orchid supply store)
Sphagnum moss (optional)
Decorative objects (optional)
Choosing your container
Terrariums come in many different and creative shapes and sizes. Most terrariums are made from
a clear glass jar with a wide mouth. However, a plastic 2-L bottle can also be used by cutting it in
half, and sliding the top half over the bottom half to cover. It is important to consider that the
wider the opening of your container, the easier it will be to place the plants.
Choosing your plants
Terrariums are often made with small mosses, lichen, and ferns. However, there are several other
types of plants that can be used, depending on the size of the terrarium, including begonias,
miniature violets, coleuses, pilea (baby tears), and others. Plants need not be purchased, but can
be collected from your yard and neighborhood. Get creative! For additional suggestions of plants,
see resources below.
Building your terrarium:
1. Place a thin layer (approx. 1 inch) of small stones in the bottom of the terrarium to help
2. Place a thin layer (approx. ½ inch) of activated charcoal over the stones. This acts as a
filtration substrate and keeps the water cleaner.
3. Place a thin layer of sphagnum moss or a fine screen over the charcoal to act as a barrier
to prevent settling of the soil. (Optional)
4. Place a layer of potting soil approximately 2” deep.
5. Make small holes for roots and carefully plant your plants in the soil.