A terrarium is a self-contained growing environment for plants, customarily a glass or transparent plastic container. They range in size from small bottles with a few miniature plants to large aquariums filled with a variety of moisture-loving tropical or subtropical plants. They are ideal for the home as they require little care once established and can be grown with minimal direct light.
Terrariums have a long history. They are commonly attributed to Dr. Nathaniel Ward, who was experimenting with hatching cocoons in jars in 1827 when he discovered that fern spores had sprouted in the soil. He later experimented with growing ferns in glass jars and discovered that they also thrived, which gave rise to the first terrariums, called Wardian cases. Wardian cases became popular in Western Europe and the United States, adorning parlors and sitting rooms in the homes of the wealthy. Growing ferns soon gave way to the craze of growing orchids in these self-contained environments.
Terrariums range in size and shape, but all are made from transparent plastic or glass for easy viewing and to allow sunlight to penetrate. Tropical terrariums, requiring high levels of humidity, are sealed to maintain the moisture level. Water from the soil and transpiration of the plants rises and collects on the sides of the terrarium, where it cools and condenses and returns to the soil. Desert terrariums are designed with an open top to allow water vapor to escape and maintain the arid conditions desert plants need to survive.
The bottom of the terrarium is typically layered with an inch or two of sand or gravel, covered with a layer of charcoal and topped with potting soil. Miniature plants are planted in the soil and misted lightly.
Terrariums are placed out of direct sunlight to prevent them from overheating in the strong rays of the sun. A few hours of filtered light may be enough for some plants to thrive.
Decorative stones, pieces of driftwood or ceramic miniatures may be added to the landscape. Hills and valleys are created with mounds of soil and tiny pebbles. Moss may be used to cover the soil and keep it moist.
The closed design of some terrariums makes them virtually carefree once they are established and a proper moisture balance is obtained. In the early stages, the cover may be opened to allow moisture to escape if the terrarium is too moist; water may be misted onto the plants to increase moisture if the terrarium is too dry.
Brightly colored tropical plants bring life even in the midst of cold, dark winters.
Terrariums are generally grown for their decorative features and are used as focal points in home decor. They can be used to maintain delicate outdoor plants that can not survive cold winters and can even be used to start difficult seeds for exotic houseplants or to plant outside in the spring.
Terrariums provide gardeners with an indoor gardening area when it is impossible to garden outside. They are easy to maintain and require little care, making them ideal for those who enjoy plants but suffer from limited mobility.
Terrariums make it possible to enjoy the wonders of nature all year long.