Chapter - 05
Miniature Greenhouses

growing orchids

Growing orchids in Wardian cases (small glass boxes) placed in some strategic spot in your house is neither a new idea nor a temporary expedient. Such cases have been used for more than a hundred years since Dr. Nathaniel Ward, a London physician, invented them to protect rare plants shipped to England. Charles Darwin used them for his classic orchid studies. Commercial growers propagate orchid seedlings in them. Scientists employ them for controlled plant experiments.

growing orchids


Wardian cases accidentally developed from an experiment with moths. Dr. Ward wanted to watch sphinx moths emerge from their chrysalises. He placed a cocoon on damp earth in a small bottle lightly stoppered with tin. To his mild astonishment a few weeks later a blade of grass and a fern sprouted in the bottle, and he kept both of them there for four years.

Later Dr. Ward—a plant hobbyist who knew the difficulties of importing delicate plants—devised a box made of glass panes set in wood. He turned the box over to the Royal Horticultural Society for experimentation. The case was an immediate success, becoming a necessary piece of equipment for all plant hunters from that day to this. Some of the famous plant cargoes, other than orchids, carried in Wardian cases include the tea plants Robert Fortune pilfered from the Chinese and quinine plants from Peru.
Wardian cases offer the cheapest and most efficient method open to amateur gardeners who want to try their luck with orchids in a small way. Moreover, the busy professional man who likes gardening can give orchids in Wardian cases all the attention they require; such cases can be made nearly automatic in operation.

A homemade glass case thirty inches square will hold about twenty-five orchids of various sizes, costs approximately $20, and can be built to suit an odd corner of your living room, back porch, or terrace. You can buy fancy ready-made Wardian cases, of course; or adapt a tropical fish aquarium equipped with an automatic heating unit.

Some amateurs have been satisfied for a time with oversized bell glasses, either bought or homemade. Cutting the bottom from a one-gallon or five-gallon jar and leaving the handle and cork on transforms it into a quaint bell glass. Place a potted orchid on a plate of moist gravel, expose it to the vagaries of the climate during the morning and afternoon, cover it during the evening and night with the glass. Basically a bell glass is a terrarium, a direct descendant of a Wardian case. This method requires a bit more watchful attention, but is extremely effective for the smaller, showier orchids.

For your first orchid box there is nothing like a back porch or terrace, where the appearance of the box isn't too important. Later, after you've tried growing orchids and succeeded, you can go in for more elaborate cases.

A large case may be made from five glass sashes thirty inches square, twenty feet of five-inch tongue-and-groove lumber, thirty feet of one-and-one-half-inch battens, and a strip thirty inches long by one and one-half inches wide. This material should be available at any lumber yard.

A hardware store will supply six two-inch angle irons, four one-inch hinges, screws and nails, a thirty-inch square of galvanized tin, a twelve-inch square of asbestos, two hook-and-eye latches, one-fourth pint of aluminum paint, and a bottle of turpentine.

Your electrical store may have special heating equipment. If not, then pick up a seventy-five-watt poultry brooder heater, fifteen feet of drop cord, a wall plug, a wafer thermostat, and a thermometer.

And that is all the material you will need to be able to say eventually to your friends, "Come up and see my orchids."

Set three of the sashes on edge at right angles, thus making a back and two sides. Use four of the angle irons to hold the sashes solidly together. If you are very careful you can nail sashes, but you take a chance on splitting the frames. Across the bottom of the sashes nail the tongue-and-groove boards for a base. Use the remaining two angle irons to hold a one-and-one-half-inch-wide strip across the top front. This will prevent the free ends of the sashes from warping. Lay the fourth sash on top and hinge it to the back so that it opens like a lid. Hinge the last sash to the front so that it opens sideways.

Put the two hook-and-eye latches on the front hinged sash in order that it may be locked shut safely. Through the bottom boards, about twelve inches out from the center and equally spaced on a circle, bore four two-inch holes for air vents. Since the case will be warmer inside than out, a natural draft will result, providing continuous circulation of air up and out the slightly opened top.

Give the inside of the case a good painting with the aluminum paint. You may paint the outside of the case some other color, if you wish, but use only aluminum for the interior. Aluminum paint diffuses and reflects light better than other paints and is an excellent protection for the wood. If you can't get aluminum paint you may use white lead.

While the paint is drying make a tray twenty-six inches square out of the galvanized tin. Bend the edges of the thirty-inch square up two inches and pinch the four corners together to make a watertight tray, or cut and solder them. Cut the battens in twenty-nine-inch lengths and nail them about their own width apart on three battens used as rails; this is your rack on which to set the orchids.

Your case is ready for installation. Put it about a foot away from a window having a southeast or southwest exposure, or in a similar outdoor situation. Set it on blocks at least an inch above the table, or in a frame of its own. Place the asbestos in the bottom of the case, the air holes circling it. On the asbestos lay the brooder heater. Incidentally, a twenty-five-watt or larger carbon filament incandescent lamp does nearly as well as a heating unit; the temperature of the case may fluctuate a bit more, but that is all. Mount the thermostat on one of the fixed window sashes near the top. Use the drop cord to connect the thermostat and the heater, and finish off the free end of the cord with the wall plug.

In each of the four corners of the case place a block of wood four inches square, or invert four-inch clay flower pots to support the tin tray. Place the tray in the case and fill it to a depth of one inch with one quarter-inch gravel. Slide the rack of battens on top of the tray.

Put a thermometer into the case near the thermostat, turn on the electricity, and watch the temperature rise to 50° F. Make your thermostat adjustment so that the temperature won't fall below this point.

The care of orchids in a Wardian case is the same as that for greenhouse culture. But it requires a little more constant watchfulness, a little more exact application of the rules. That is one of the best reasons for starting with a Wardian case, or bay window. It will make an expert orchidist out of you more quickly than if you proceeded more ambitiously.

Your orchids kept in a Wardian case will require a bit less water at the roots than those in windows or greenhouses; water will last longer in the small area of the case. Watch the temperature of your case on warm days. Remember that the higher the temperature goes, the higher the humidity must be—the lower the temperature, the lower the humidity. In the confined space of an orchid box your humidity-temperature correlation must be as exact as possible. A humidity gauge in the case is handy. As long as it reads not less than 40 per cent from late morning to about midnight, your orchids will do well. You can guess at the humidity by the amount of water condensing on the sash. If the glass looks somewhat misty, the humidity is about right. If condensation is heavy in large drops, open up the case and dry it out a bit.
Always leave the top of the case open a half inch or so to insure continuous circulation of air and to remove excessive moisture. On hot days you may have to raise the top four or five inches, lowering it toward evening. The front of the case is rarely opened except to handle and water the plants, or to dry the case quickly.

When you get up in the morning, open the front so that the interior and'the plants may dry out. After breakfast pour about a quart of water over the gravel. This water should provide humidity for the next twenty-four hours.

You can supplement the humidity, particularly on very hot, dry days, by spraying the orchid leaves with water in the afternoon, if you want them to remain at their healthy best. Again it is repeated that in dry climates and dry houses, Wardian cases may not furnish optimum humidity requirements and orchids in them may need frequent syringing.

Remember that, with Wardian cases indoors, light is extremely important. The case must be placed in the best-lighted spot. During winter it should receive lots of unobstructed sunlight. During summer shade it with Venetian blinds, lace curtains, or muslin tacked to the sash. Never paint the glass.

And that is the most elaborate piece of equipment you may need to enjoy the luxury of orchids in your own home. An advantage is that most of your adjustments are automatic: a well-regulated Wardian case will almost care for itself. But you should be warned: no matter how you start, one Wardian case will lead to more. In the end you may be like the amateur who kept building Wardian cases until he had five. Finally he built a small greenhouse to care for his rapidly increasing collection of orchids.

Are You Ready To Move Onto The Next Lesson? Click Here...