(Credit: Oklahoma State University)

Dr. Nathaniel Bagshaw Ward was a 19th Century London physician who had a keen interest in nature, including observing insect behavior. When studying a sphinx moth emerging from a chrysalis he had buried in moist earth in a closed bottle, he noticed a seedling fern and grass growing inside. He watched the plants grow in this encased environment for four years, without adding water or removing the cover. Thus, the modern terrarium (originally was known as a "Wardian case") was born.

The first terrariums were known as Wardian Cases and were considerably larger than most terrariums today. (Credit: Oklahoma State University)

Terrariums are clear glass or plastic containers filled with small plants. They are an interesting way to grow certain species of plants in a home that might be too hot or the air too dry for most plants to thrive. Additionally, they are a fun project for children and help to introduce the next generation to the fascinating world of plants.

There are two types of terrariums: closed and open. Closed terrariums are more traditional and retain more humidity than open ones. Open terrariums still provide higher humidity for plants than dish gardens. Open terrariums and dish gardens require more frequent watering, but the danger of disease outbreak is reduced.

The container plays a large role in the success of a home terrarium. Nearly any type of clear container can be made into a terrarium. Examples include empty fish bowls, fish tanks, brandy snifters, old glass jars, jugs, bottles, etc.

Use a growing medium that drains well, is high in organic matter and free from disease organisms. Prepackaged "peat-lite" mixes make excellent choices.

Plants are the "jewels in the crown" of terrariums and many different plant species are suitable for use. Choose plants with a low and dense growth habit. Terrarium plants may differ in light and temperature requirements. Avoid mixing plants that require widely different conditions.

Terrarium plants should be short in stature and relatively tolerant of low light conditions. (Credit: University of Florida)

Place plants that need medium light in good light near a window or an artificial light source. Plants that tolerate low light may be placed up to 10 feet from a bright window.

Most terrarium plants are tropical in nature and require warm, but not hot, temperatures. A night temperature of 65°F is ideal for this type of plant. Day temperatures normally should be about 10 degrees higher. A few terrarium plants prefer cool temperatures and should have night temperatures about 50 to 55°F.

For best results, the growing medium and drainage material should fill about one fourth of the terrarium. Place charcoal and pebbles in the bottom of the container below the growing medium for drainage. Charcoal helps to eliminate potentially toxic by-products in closed terrariums.

In most cases, about one-third of the terrarium container should be filled with growing medium. (Credit: Steven Ward, Oregon State University)

When planting a terrarium, take plants from their pots and gently remove extra growing medium to expose their roots. Trim off yellowed or damaged leaves that show any sign of disease or insect damage. If plants are extremely pot-bound, trim off some roots to encourage new root growth. Promptly place the plant in the container. Do not allow exposed roots to dry. In the closed container, try to keep foliage from touching the sides of the container. Leaves that touch the glass may collect water and are more likely to rot.

After planting, mist over the plants to wash off any growing medium that sticks to leaves or sides of the container. Water misted over the leaves is adequate to settle the medium. Do not cover the terrarium and repeat the misting after one day. Allow the container to remain open until the foliage has thoroughly dried. Then, if the terrarium is the closed type, apply the cover. Watch the newly planted terrarium closely for several weeks for signs of disease or other problems.

Plants in terrariums should not grow rapidly and seldom need fertilizer. Don't plan any fertilization for at least a year after planting.

Since terrarium plants grow slowly, they need very little fertilizer. (Credit: Oklahoma State University.)

To download a free University of Missouri Extension publication on terrariums, please go to https://extension.missouri.edu/publications/g6520.