Chapter - 07
Greenhouses

growing orchids

Someday in the future when your preliminary orchid education is completed, your ambition will go beyond the limits of heated frames and modified Wardian cases. You will begin to look with longing and envy at the large greenhouses of established amateurs and the larger houses of nurserymen. Off you will go to buy one, and you will be appalled by the initial expense.

Ready-built and custom-made greenhouses come in all sizes from six by nine feet; and at all prices, from $150 upward to anything you may desire. Many of the houses are so built that you can start with a small unit and add sections. These ready-built greenhouses are accompanied by full directions on how to bolt them together. The bolts are supplied and about the only thing you need is a hammer, a wrench, and a screw driver. Some of the houses are conventional in shape. Others are more dramatic, or arty and, of course, cost a bit more. Nevertheless, wait until you have learned to grow orchids on an inexpensive scale before you become too ambitious. "Make haste slowly" is sound advice for beginning orchidists.

There are smaller glasshouses, however, known as sash houses, which include pits, lean-tos, and shed houses. They are much less expensive if you build them yourself. They are frequently attractive, since they can be fitted to your landscape and tailored to your house design.
 
They offer all the conveniences of large greenhouses without their labor or expense.

Although sash houses were among the first glasshouse structures devised, their use for exotic gardening is relatively new. For the past fifty years they have been undeservedly in disrepute with amateurs, but recently scientists have shown them to be extremely efficient structures. Temperature, light, and humidity—the three most variable elements of orchid culture—are easily controlled in them.

growing orchids

GREENHOUSES

Lean-to; Shed Type; Pit

In modern gardening a sash house is any glass structure larger than a Wardian case and smaller than a greenhouse —yet into which you can walk erect. It can be set against a wall of your house, garage, or solid ence as a lean-to or a shed house. Structurally, a lean-to or shed house has a half gable. Each one is really a normal greenhouse cut in half lengthwise and supported by a solid wall. In some cases, a sash house may be an oversized cold frame in which six-foot glass sashes lift upward to permit entry. Or small houses built of window frames bolted together.

growing orchids

SIMPLE GLASS STRUCTURES

Cold Pit; Sash Frame; Cold-pit Frame

Many English and American gardeners are familiar with a pit which, essentially, is constructed of two cold frames placed back to back with a sunken walk in the center. Pits are most often used to over-winter plants, but are equally satisfactory for large-scale orchid culture, since they are efficient structures for conserving warmth and require little heat to maintain temperatures above 50° F.

THE LEAN-TO HOUSE

The primary question in building a lean-to is: Where are you going to place it? Much of your future success will depend on the answer. You will need a wall or a fence, preferably with a southern exposure and free access to ample sunlight. A western exposure is second choice, an eastern exposure third. In getting a southern exposure you may have to glass-in a doorway or a window, but do that rather than select a less favorable position. Windows of your house can be enlarged to provide an indoor entrance to the greenhouse. English gardeners do this; their front doors are often glassed-over to provide small greenhouses through which you must walk before you can ring their doorbells. The more ornate of these English houses use green glass which, while pretty, is not particularly beneficial to plants.

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ATTACHED GREENHOUSE CONSERVATORIES

growing orchids 

LEAN-TO GREENHOUSE: DETAILS OF CONSTRUCTION

You yourself can do all the carpentering that is necessary on a lean-to. Simply nail two-by-four decay-resisting or treated lumber to the height and length you desire on the wall you have selected. Figure the heights in multiples of twenty-four inches, the lengths in multiples of eighteen inches. The highest point will be about eight feet, and the length roughly one-third longer than the width. Don't build too small a house; under 60 square feet it reacts too quickly to temperature changes.

Place mud sills of two-by-fours on the ground, holding them in position by nailing to stakes. In the East and North where snow is likely, bolt the mud sills to concrete foundations. Nail two-by-four studs, eighteen inches on center and four or six feet high on the long side, to the mud sill. Hold them in place with a one- to four-inch plate. Add studs to the ends, cutting them to fit the slope of the roof (leave room for a door). Then use two-by-fours set on edge to line in the roof, and flashings to waterproof.

You can buy sash bars, using them in place of two-by-fours for studs. But two-by-fours make a sturdier house. They will take glass panes simply by nailing strips of quarter-round lumber or "boot-toes" to them, about one inch in from the outer edges. The flat edges of the quarter-rounds serve as ledges on which you smear "mastic putty"—not regular putty—and press in sixteen-by-twenty-four-inch glass panes. On the vertical walls the panes are set edge on edge; on the roof overlap the panes one-half inch so that rain will run off. This technique of pressing glass panes into putty and fastening them securely is called "glazing"; any hardware salesman from whom you buy your materials can tell you exactly how to do it.

A door can be obtained from the lumberyard. Before framing-in your door make sure it will be a standard size. Specially built doors are likely to be expensive.

Provision must be made for ventilation. Some amateurs place a small, twelve-inch blade, electric exhaust fan near the top of the lean-to. The conventional method is to install several small glass windows hinged to the top of the lean-to. Such windows push upward and outward, are held open by metal or wood bars during the warmer hours of the day, and closed at night. The door provides bottom ventilation as necessary. Or several windows may be hinged to the sides as well.

growing orchids

ORCHID BENCHES

The upper right drawing is a break-a-way sketch of a widely used, inexpensive orchid bench. The tiered bench, at lower left, is excellent for the back wall of a lean-to, assuring all plants equal access to light. The bottom portion of the bench contains gravel or cinders to help conserve moisture.

A lean-to house can take one large bench or two small ones. About that, suit yourself; just don't build a bench so wide you must climb on it to reach the opposite side.

There are two things to keep in mind when building an orchid bench: First, it should be isolated from the walls and floor. You can do this by setting bench legs in pans of water and leaving an air space between the bench and the wall; in this way your plants are protected from snails, slugs, and ants and the pests they carry with them. Second, there must be continuous air circulation upward through the bottom of the bench. For that reason, the top of an orchid bench never is built solid. Wire netting of one-fourth-inch mesh may be stretched tightly across the bench framework, or strips of lumber two inches wide may be nailed to the bench frame one inch apart.
 
Depending on the number and width of your benches, mark off a walk about thirty inches wide and as long as necessary. Line it with bricks. Fill the left-over areas beneath the benches with three inches of pea gravel or cinders. Either material will give the lean-to a neater appearance and, when moist, more consistently maintained humidity.

All wood surfaces will require protection. Inside wood should be brushed with several coats of aluminum paint, which reflects and diffuses light, gives the glasshouse a clean, bright, cheerful look, and is also an excellent preservative. Outside wood may be painted any color your fancy dictates, provided that you use a lead-base paint. One of the most attractive lean-to houses in Southern California is painted blue at the base, with a blue trim around the sash.

Heat for a lean-to house may be unnecessary in areas where frost is only an occasional visitor. In all other sections, heating should be provided. There are many ways of heating a small house, most of them inexpensive, listed in bulletins published by the United States Department of Agriculture. The simplest is the electric heater and fan combinations that pull about 1,200 watts. Oil stoves may be used if the detrimental combustion products are piped out. Open gas burners have not been too successful because of the injury that incomplete combustion may do to orchids. However, by adding a metal-alloy honeycomb coil against which gas flames may be projected, more perfect combustion is assured. If your home is equipped with steam heat, pipe it into the lean-to. Add a solenoid valve, connected to a thermostat, set the thermostat at the temperature you want—and forget about your heating problems. Several amateurs in the East have done this with astonishing success.

Humidity in a lean-to is built up by sprinkling the pea gravel once or twice a day as needed. You can make humidification automatic by adding a humidistat, a magnetic valve, and several spray mist heads. Set the sprays under benches where the water mist won't drift over the benched plants. A small electric fan helps distribute the mist and keeps the air moving.

The regulation of light is a little more troublesome. A lean-to with a southern exposure should have a light coating of whiting on the panes during the summer, probably none in the winter in northern sections. Southern states require shading the year round. Eastern exposures often do not require summer shading if the lean-to is shaded by your house from midday on. Western exposures must be protected during afternoons. Lath roller blinds and muslin are the best and neatest shading materials for home greenhouses.

These details on a lean-to are necessarily limited and serve only to point the way. When you reach this stage of orchid culture, it is suggested that you go to the nearest library and consult any one of the dozens of books on the construction, maintenance, and operation of greenhouses.

THE PLANT PIT

A plant pit is an almost perfect housing for orchids, no matter in what section of the country you may live. It is built low to the ground, the sides only one foot high; the center about four feet above ground level—higher if snow is inevitable. Structurally, a pit is simply a gable greenhouse top that has been cut off and placed on the ground. Having less interior air space than larger structures, the pit is heated more quickly and, being well insulated, keeps warm longer. The sides may be of glass, but are more likely to be of inch thick redwood or cypress planking against which earth is banked to provide better insulation.

To build a plant pit, begin by marking off its area in an out-of-the-way section of your garden. This area can't be near trees, tall shrubs, or buildings which might shade it. As a rule, a pit will be ten or twelve feet wide and twenty feet long. Lengthwise, the pit always will extend north and south, the gables sloping equally to the east and west in order to insure maximum sunlight.

growing orchids
 
PIT GREENHOUSE: DETAILS OF CONSTRUCTION

Mark off a path thirty inches wide down the center. Dig it out to a depth of thirty inches. Use the free dirt to bank the sides of the pit later. Set boards along the walls of the walk to prevent the earth from crumbling. A better permanent job can be done with brick or concrete.

Along the outer edge of the rectangle place posts, embedded in the ground. Nail planks to the posts for the sides. Concrete sides are better in areas where the winters are severe. Don't forget that each end of the pit will require shaping. Allow enough lumber so that you can saw out two triangular pieces which will make a base for the gabled glass roof. From the top center of one end to the center of the other run a two-by-six ridgepole. This may be supported by several "V" frames.
Then add the sash bars or two-by-fours, using the method previously described for lean-to houses. Putty and press in the glass panes. A space for ventilation at least twelve inches wide must be left on the top lee side of the roof. It need not be longer than ten feet, and it can be centered between the ends of the pit. Cover it by hinging a series of small glass windows to the ridgepole.

growing orchids
 
L. Sherman Adams

LAELIOCATTLEYA VALENCIA, VAR. DORIS

growing orchids

L. Sherman Adams

BRASSOLAELIOGATTLEYA MINPUSS

growing orchids

growing orchids 

DIAGRAM OF A SIMPLE HOT-WATER HEATING SYSTEM

All pipes slope slightly in the direction of the water flow in order to assure a circulatory system. The heater may be a geyser or small-capacity water heater which is gas fired. The water reservoir is left uncapped as a safety precaution and for the purpose of adding more water to the system. The use of a simple thermostat can make the operation automatic.

Complete the house by adding a door and steps to the north end of the pit. This can be done in one of two ways: cover the exposed steps and walk with an old-fashioned sloping cellar door; or build a small porchlike shelter that will rise several feet above the top of the pit.

Since the ground in the bench areas will get mucky from sprinkling, it should be covered with three inches of pea gravel or cinders. If you contemplate a bench, which is advisable, build the side walls of the pit about six inches higher. Orchids should be close to the glass roof, but not touching it. Allow for at least three inches of clearance between the top of your plants and the glass.

The management of a pit is no different from that of a lean-to or other similar glass structures. Shade must be provided in summer, ventilation and humidity must be supplied, and winter heating may be necessary. Any of the heating methods outlined for lean-to houses will work for pits. A gravity hot-water system can be installed. It is an excellent means of heating, probably the best and safest for all plants. It is not considered here because any brief mention of hot-water heating systems could not begin to do justice to the better and more factual information contained in already published books on greenhouses and their management and heating.

Without a doubt, though, some sort of greenhouse—from the smallest six-by-nine-square-foot house upward—is the best structure for growing orchids. In a glasshouse you readily can control all the factors governing orchid growth. Nonetheless, amateurs with plant sense can grow orchids in all kinds of conditions that commercial men would find impracticable since commercial growers must show a profit. If you can grow any common plant—azaleas, zinnias, carnations, or roses—don't let anything scare you from growing orchids, regardless of the conditions or climate in which you live. Study your home conditions, learn what others have done under similar handicaps—and go ahead on your own. In greenhouses or in gardens, in homes or in cold frames you will find orchids more fun and more of an adventure than any other plants.

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