(By Wanda Macnair)

It is so easy to grow terrarium plants in enclosed containers, because they need not be constantly watered or groomed.  In their native habitat, plants requiring extra humidity were growing on the floor of the rainforest, or in tree crevices or on rocks with a thick canopy of growth overhead.

The most important things to remember about their care are to keep the containers out of direct sunlight, and to try to keep them on the cool side.  Many unsuccessful growers have forgotten that the plants love humidity, but they do not like wet feet.

The medium I use for growing begonia plants in enclosed atmospheres is long-fibered sphagnum moss.  I pour boiling water over a small amount to get rid of any “livestock.” When the sphagnum cools down enough to handle, I cut it into small pieces, and add just a small amount of perlite.  If the sphagnum is quite wet, I use newspapers or paper towels to soak up some of the moisture. 

When planting I use about ¼ inch of gardener’s charcoal on the bottom of the container.  Then I add one to three inches of the prepared mix.  After creating a depression in the medium, I place the plant and usually pull up a bit of the medium around the crown of the plant to provide support.  Because I start with a moist medium, I often do not need to add any moisture.  If it is necessary to further moisten the container, you may use a turkey baster to add just a bit of water around the edges of the container.  After planting it is necessary to observe the container closely until you can tell if the plant is too wet or too dry.  If the sides of the container produce too much condensation, you may wish to blot some of the moisture, although a certain amount of condensation is normal, especially during the warmest and coolest parts of the day.  Paper towels are great for this job.  If you have really overwatered a plant you might even take it out of the container and set it on several paper towels.  Newspapers work, too, although not as rapidly.

Many terrarium growers don’t want their plants to grow too fast, and hence, do not fertilize.  However, many growers do fertilize.  If you insist on fertilizing, the top of your medium might eventually grow a type of mold.  Don’t worry about it, but you can just remove this mold, and add fresh medium on the top.  From time to time plants need a bit of refreshing, and want to have fresh planting medium, anyway.

It is a theory of mine that plants begin to go downhill as the moss begins to decay and causes some acidity to build up.  To counteract this, I like to use a pinch of ground limestone in my mix.

Another plus for growing in contained atmospheres is that if a plant does not have any mildew spores on it, it will not develop mildew because any spores are blocked out by the cover.