GARDENER'S READING ROOM
The Art of Gardening
Indoor Plants

Terrariums, Conservatories, Bottle and Dish Gardens & the Plants that Love Them... part I, Tropical Terrariums

Terrariums are popular - again! Traditionally, a terrarium is an unheated (usually glass) enclosure with a lid in which medium/low light tropical plants are grown. It functions as a small greenhouse, creating its own self-contained eco system. (There are other types of terrariums and bottle and dish gardens that encompass different plants and conditions; I will talk about them in the next article.)

Before you put one together, think about where you're going to display it. Keep in mind that the plants need sufficient light, but not direct light. Diffused light coming through a sheer curtain or in a north window or back more than 5 feet from a west or south window is perfect. Don't put your terrarium near or over a heat source ... the temperature in the enclosed environment will soar and your plants will burn.

The greatest point of contention, for me anyway, is in building it. The most frequent set of instructions we see has people creating layers inside the container: drainage material, charcoal and soil. Since roots have a difficult time making a transition from one layer to another, why make it harder for them? The layers have a way of raising the water table, and that actually causes things to stay wetter than they should.

I use a good indoor potting media to the depth of 1⁄4 the height of the container and add horticultural charcoal (which helps with drainage, sweetens the soil and absorbs impurities) to 1/3 the volume of the media. So if the container is 10" deep, use about 2.5" of media and about 1" of charcoal. Mix them together and add to container. You can sculpt a little landscape if you want, creating hills and adding small accents such as rocks or figurines. Before planting, place your plants (in their containers) where you think you want them. When you are happy with the way they look, plant them.

Pick plants that are compatible and that can be pruned or pinched. (See below for a partial list of plants that like tropical terrarium conditions.) If they do get too big, they can be removed and put in their own container and replaced by a smaller plant. Most importantly, have fun!

Some plants for a Tropical Terrarium

Temperate Plants that will do well in Tropical Terrariums

By Mary Ann Greco, Indoor Gardening Department
Skylights Autumn 2009, Vol 24, No. 3

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