Making Your Own Terrariums

Kent Kobayashi
Tropical Plant & Soil Sciences Dept.
College of Tropical Agriculture & Human Resources
University of Hawaii at Manoa


A terrarium is a clear glass or plastic container filled with plants and/or small animals (frogs, turtles, or lizards). They resemble miniature gardens. Terrariums are attractive and easy to care for--just plant it and forget it. And because a terrarium recycles its water, it need very little attention.


All you need to build a simple terrarium:


Before beginning your terrarium, decide whether you prefer a tropical, woodland, or desert theme. Keep in mind the temperature and light conditions in the location where you plan to place the terrarium. Select plants that are suitable for that location.

  1. A drainage layer is essential to ensure roots are not sitting in excess moisture. Place a 1/2 to 1-inch layer of small gravel or pebbles in the bottom. Add a layer of sphagnum moss. This serves to keep soil from seeping into the drainage layer.

  2. Sprinkle crushed charcoal in the bottom to keep the soil fresh. This keeps odors from developing.

  3. Add 1/2 to 1 inch of well draining, fertile potting soil. If the soil clumps when squeezed, add perlite or vermiculite to add texture and porosity. You may wish to landscape the soil by adding little mounds and depressions in the soil.

  4. Dig small holes in the soil and place the plants in them, making sure all roots are in the hole. Firm the soil gently around the roots.

  5. Avoid clutter. Often a simple arrangement with a few well-placed, attractive plants are much more pleasing to the eye. Space should be left between plants to allow them room to grow and to facilitate air circulation.

    If the terrarium will be viewed from only one side , place the larger plants in the back. If it will be seen from all sides, the larger plants should be placed near the center, surrounded by the smaller plants.

  6. Water lightly if needed. After covering the terrarium, place it in a shaded area until the plants become re-established. Watch carefully for a few days. If water condenses heavily on the inside the container, remove the lid so the excess moisture can evaporate. If the plants wilt and no condensation forms, add a small amount of water.


Closed terrariums. A closed terrarium requires a minimum of care if it is kept sealed. It typically does not need to be watered because plants recycle the moisture they use. Water lightly only if it gets dry. Open the lid only to allow excess moisture to escape.

Open terrariums. The open terrarium requires more frequent watering, but there is less disease buildup.

General. Place the terrarium in a bright location, but not in direct sunlight. A little direct sunlight can cause temperatures in an sealed terrarium to rise rapidly.

Remove any dead plants and leaves. Prune back excessive growth as needed. When a plant gets as big as you want, pinch it back to encourage bushier growth.

Adding fertilizer is generally not necessary since the plants should not grow rapidly. Good potting soil should contain enough nutrients. Over time, the soil can be "refreshed" by scraping off the top layer of soil and adding some fresh potting soil. This will add a small amount of nutrients. If the leaves begin to yellow after a few months, add a little water soluble fertilizer.

Require little attention, terrariums will grow successfully on their own for several years.


Gardens Under Glass, do it yourself network
Terrarium Time, Home & Garden Television

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