GROWING IN GLASS HOUSES
Plants can thrive on neglect inside Wardian cases, a.k.a. terrariums
In 1827, a London physician with an interest in caterpillar metamorphosis built small glass boxes to contain the cocoons and emerging butterflies. Peering into the “dirt” in one of the boxes one day, the physician, Dr. Nathanial Ward, noticed that a fern spore had germinated. Ward became so enthralled with the way the developing plant was able to flourish without care in the box that he changed his course of study. In 1836, he published a book entitled On the Growth of Plants in Closely Glazed Cases.
Wardian cases, as the glass boxes came to be called, became all the rage in Victorian England. Plants were protected in the cases from the chilling drafts, dry air and gas fumes of Victorian homes.
Plant explorers also found a use for Wardian cases. Live plants from exotic lands could be transported by ship to England, protected in the cases from salt air and changing climatic conditions. Today, we usually call such plant cases “terrariums.”
CARE-FREE GARDENING
Whether in the home or on a ship, plants in Wardian cases need little care. The small amount of water that the leaves give off in their humid environment condenses on the glass and dribbles back to the roots. Oxygen released each day from photosynthesis is used each night in respiration. Ward reputedly grew ferns in one of his cases for 15 years without any care at all.
A Wardian case full of lush green plants is a year-round oasis, even if today’s homes are less drafty and the air is cleaner than in the homes of Victorian England.
Aside from decorative value and ease of care, a terrarium provides the humid, boggy environment essential to the cultivation of certain plants.
CONTAINER OPTIONS
Many kinds of containers can serve as Wardian cases. I have made my own, using glass and silicone glue. Other possibilities include 5-gallon (18L), water jars, 1-gallon (4L), canning jars, aquariums and oversized brandy snifters.
Large plastic soda bottles are easily converted into small terrariums. Some bottles have a dark plastic piece that covers the domed bottom. Pry that plastic piece off the bottom and then cut the bottle in half crosswise. Invert the dome over the base you initially pried off, and you’re almost ready to plant.
Once you have settled on a container, wash it thoroughly. You won’t get another chance. SOIL AND PLANTS
To plant, start with a layer of charcoal, which will keep the soil “sweet.” Next, add potting soil, the amount depending on the container, the plants and the type of “landscaping” you want. Perhaps, depending on your “landscape,” one or more rocks also. Finally ... the plants.
WATER WITH CARE
Choose plants that thrive in high humidity and will not grow too fast. A spider plant in a terrarium I made a few years ago has pushed off the wooden lid and is climbing out the top. Good choices for larger terrariums are dracaenas, dieffenbachias and palms. Low-growing plants include English ivy (choose smallleaved cultivars), prayer plants, ferns, baby’s tears and mosses.
The climate within a closed container allows cultivation of insectivorous plants like the Venus fly trap, pitcher plant, and sundew, all of which need moist, boggy soils and very humid air. (And perhaps a fly every now and then.)
The final step, watering, is the most critical. Add water gradually so as not to form puddles in the soil. Add enough water to moisten the soil without making it sodden. Then set the terrarium in its permanent location, in bright light but out of direct sun, and watch for condensation. If the right amount of water has been added, there should be slight condensation on the glass each morning. If you have overwatered, let the case dry out for a few days with the lid off.
Note the succession of plants and perhaps other organisms that thrive in the unique ecosystem created within each terrarium. Something always thrives. My first terrarium was far too sodden, but it did grow an attractive and interesting crop of mushrooms, in addition to the plants that survived.