Greenhouses run the complete range of possibilities from elegant conservatories to compact window greenhouses that fit cosily into a kitchen window frame. Whatever the size, similar recommendations for selection, design and installation apply. There are three major types of greenhouses to think about carefully. The lean-to greenhouse is generally small, about 6 to 10 feet long. One of its long sides is formed by the side of the house to which it is fixed. Fairly inexpensive to make and look after, its major disadvantages are a shortage of space for an expanding collection and a tendency to become hot and cool off more rapidly than is desirable.

The attached greenhouse is an extension of one’s home, connected at the narrow end instead of the long side, as with the lean-to greenhouse. It is usually large and thus capable of providing more reasonable control over humidity, ventilation and expansion problems. Some homeowners include a living area into a lean-to or attached greenhouse.

The free-standing greenhouse is unfixed on all four sides. It is the most expensive to construct but, apart from some inconvenience of access in unpleasantly weather, it gives maximum light and the best control. Some space must be sacrificed for a work bench and storage area.

Visit as many orchid greenhouses as possible, and consult books on and manufacturers of greenhouses before making a final decision. Where space is limited inside the home, window greenhouses provide a main space in which to grow small-growing orchids. Choose for a model with vents and small fans that improve ventilation. Two or three shelves increase space; they may be hard, to prevent water from falling in drops on the plants below, or made holes in them to aid air circulation.

Size

The best size with which to begin is a greenhouse 14 feet wide and 14 to 20 feet long. This provides a center bench as well as two side benches. Such a greenhouse may seem huge at first, and unnecessary for a first collection, but there are a number of factors to consider. First, those considering a greenhouse are serious about orchid growing. Therefore, the collection will inevitably grow very quickly. What seems to be sufficient space today will become a very serious limitation in two years. Second, since a large greenhouse is better in the long run, it is cheaper to build it now than to add an extension onto a smaller one in the future.

Light

Regardless of the type, find the exact position of the greenhouse to get maximum light. The best position for a free-standing one is on a north-south axis so the sun goes across the whole length when it moves from east to west. A lean-to or attached greenhouse should also have a maximum exposure, east or south, but never north. Avoid not far away shade trees or shadows from adjacent homes or buildings. It is easy to reduce intense of light that is too intense; it is fairly impossible, nevertheless, to provide light when the greenhouse is shaded by forces beyond the owner’s control. There are a number of factors to be considered in planning the construction of a greenhouse. Most demand professional advice.

Structure

The establishment of a greenhouse is an additional but necessary expense. All greenhouses should have one. In areas where temperatures fall below 35 F, the establishment, whether of poured concrete, brick or cinder, must extend well below the frost line. Otherwise, the greenhouse will become bent and twist. The floor is always the leveled earth, never a block of concrete, thus making sure suitable drainage. A clay-earth floor may be layered with several inches of cinders or gravel.

Benches

Build the height and width of benches for convenience, usually 30 inches tall and 33 inches wide. The center bench may be twice this width because it is accessible from two sides. Choose treated lumber that is not affected by moisture, or aluminum and steel, which have proven more hard-wearing, even though, at the beginning, they are more expensive. The top surface of the benches should give aeration and so should be built either by redwood or cypress strips, spaced about their own width apart , or by a strong aluminum mesh. thus, Air can circulate upward through the pots.

Heating

A heating system is very important and necessary in any area which has recorded temperatures below 45 F. It is also wise to give an emergency heater. Too many collections have been lost to freezing because of oversights, power failures or lack of suitable maintenance of the heating system. A wide selection of heating systems can easily be found: steam, circulating hot water, ducted hot air, natural gas. Where bottled gas must be applied, completely and in every way, no fumes should go through the greenhouse. Orchids are infamously susceptible to ethylene gas and will soon die if any is present.

Cooling and Ventilation

Except in very warm weather conditions, a cooling system is generally not essential, because manual ventilation is sufficient for those extra warm days. To grow odontoglossums and similar cool-growing genera, it may be advantageous, even necessary, to invest in an evaporative cooler in order to give the low temperatures these orchids need. Automatic humidifying devices are necessary and should run in combination with sufficient ventilation mechanisms. Side and roof vents run automatically or manually, in addition to several fans running continuously, will keep the moisture-laden air moving freely in every part of the greenhouse. Shading will depend mostly on the characteristics of the particular weather conditions and will have to be adapted accordingly.