At some time before 1836, English physician and entomologist Nathaniel Bagshaw Ward wanted to observe insect metamorphosis. He placed a caterpillar in a capped wide-mouthed glass bottle together with some mold to watch the insect develop a chrysalis and transform into an adult butterfly.
There was nothing exceptional about his doing this, but in the process Ward observed how, during the daytime sunlight drew moisture to the top of the bottle and at night this would circulate back into the soil. Even more to Dr. Ward's surprise, a seedling fern and a sprout of grass grew inside the sealed bottle. He had earlier tried to grow these same plants in his outdoor garden without success and for that reason he decided that the isolated ecosystem he had created protected these plants from pollution from local factories.
To see what would happen over time, Dr. Ward placed his jar in a window of his study to observe it. The plants continued to thrive for a period of years with no outside intervention whatsoever. Thus was the science associated with terraria initiated. But they were not called terraria at first. They were called Wardian Cases in honor of their founder. Today some still use that designation.
Dr. Ward wrote about his discovery in a book titled On the Growth of Plants in Closely Glazed Cases in 1852. His book, a delightful Victorian presentation, is still available on the web.
Despite Dr. Ward's initial experience, closed terraria require special organization to operate effectively. Since there is no drainage, a base of gravel, small stone or even broken pottery prevents an accumulation of water that would damage plant roots. On this a thin layer of charcoal can help keep the soil fresh. What indoor gardeners call potting soil can serve in this role for most terraria, but for a drier environment special cacti-succulent soil may better serve. These layers should make up about a third of the depth of the container.
Especially important to the successful creation of a self-contained terrarium is the choice of plants. Since this is a kind of miniature garden landscape, it is obviously inappropriate to include plants that will grow quickly and overwhelm the container. Tara Heibel and Tassy de Give's Sprout Home blog recommends: ferns, mosses, baby’s tears, hypoestes, fittonia, ivy, peperomia, sanseveria or schefflera. Even some of these plants need occasional pruning. Care must be taken not to introduce insects and disease when establishing a terrarium.
Only a few sources distinguish a terrarium from a vivarium by including plants in both but animals only in a vivarium. In any case it can be interesting to include small animals in such an enclosed ecosystem; however, they complicate matters significantly. Even tiny turtles, for example, will quickly destroy a vivarium. Some possibilities include: crickets, tarantulas, chameleons and small frogs and toads. It is usually necessary to provide an additional water source for whatever animal is introduced.
Now where should a terrarium be placed? The problem is heat. This enclosed space is easily overheated so it is necessary that it not be exposed to long periods of direct sunlight or to indoor heat sources. Some terraria owners move them from indoors in winter to outdoors in summer.
Terraria offer wonderful opportunities to observe nature. Commercial versions are widely available but here is an opportunity to develop one yourself. Next Sunday, September 21 at 2:00 p.m., Sara Johnson of Sylvatica Terraria in Buffalo will host with Buffalo Audubon staff a Make and Take Terrarium Workshop at the Beaver Meadow Audubon Center, 1610 Welch Road, North Java NY.
Participants of all ages will learn how to make a terrarium: an easy-to-care for, self-contained eco-system and an artistic display of plants. They must bring their own terrarium: a glass bowl, dish or other container, as well as any trinkets to be included in their creation. If you wish to create a closed terrarium, the kind I have talked about in this column, you will need to have a large enough opening to be able to introduce plants. At the workshop all other materials will be provided.