Orchids – The Growing Environment

Orchids In The Home.

You do not have to have a greenhouse to grow orchids. If you can grow a houseplant, you can enjoy growing orchids. Also, if your climate is suitable, orchids grown indoors over winter can be moved outside to a protected area for the summer.

As light is essential for orchids, the plants will need to be close to an east or west window, or a lightly shaded south-facing window. Orchids have been grown successfully under these conditions, but avoid those requiring very high light levels. On a window facing more to the east or west Phalaenopsis will grow well if the room temperature does not fall too low in cold weather. Other low-light orchids which will flower with this orientation include, to mention a few, Phragmipedium, Paphiopedilum, Miltoniopsis and, in some locations, some of the more temperature – tolerant Masdevallia.

The Shade House.

Whatever your local climate, orchids are going to need at least as much shading as they would have in their natural environment. A shade-house is usually a wooden or metal framework covered with a monofilament black shade-cloth. The pitch needs to be reasonably steep or some support such as wire netting placed under the shade-cloth to prevent it from sagging. Before we had plastic shade-cloth these structures were usually constructed with wooden laths to control the light. Lath houses are still being erected and provide very solid low-maintenance housing.

It is common practice to cover the shade-house with a transparent plastic cover to protect flowers during the flowering season. The better modern plastics contain an ultraviolet inhibitor (that stops UV destroying plastic) and are quite long-lasting. A totally enclosed shade-house should not only give control over light but also give protection against insects, winds and, where needed, light frosts. A house with a permanent roof to keep rain out, but open at the sides, is a popular structure for year-round cultivation of cooler-growing orchids, such as cymbidiums, where protection from only light frosts is necessary. This arrangement is common even in tropical countries, where similar protection from rain is required.

The Greenhouse.

A greenhouse is usually thought of as an enclosed structure where the grower can attempt to create a climate similar to that experienced by the orchids in their natural environment. The control of light intensity does present practical problems. When greenhouses were glasshouses it was relatively easy to paint shading material on the glass in summer and remove most of it during the winter. Various kinds of plastics have largely replaced the glass. They have the advantage of needing a less exacting framework and of providing a more watertight long-term covering. Some modern materials seem to be long-lasting -but just how long remains to be seen. You can’t paint shading materials on most of them. The alternative is shade-cloth. If fixed on the outside, the inside temperature will run cooler because the unwanted light is not allowed to enter and contribute to interior heating. If on the inside, the same degree of shading is provided but the unwanted light also raises temperatures. Shade-cloth is usually fixed inside the greenhouse because, despite the disadvantages, it is less of a nuisance to control there.

A wide choice of aluminium-framed greenhouses supplied in kit form for do-it-yourself assembly is currently available. A spanner and a screwdriver are almost the only tools needed to erect them. Most have clear plastic down to ground level and, although we do not grow orchids down there, light entering under the benches adds to the internal heat in hot weather and to heat loss in cold weather. Small greenhouses suffer from greater temperature extremes than larger ones. The ideal is a greenhouse erected on a wall of poured concrete, cement blocks or bricks to bench height. Otherwise, the external walls under the benches can have the light obscured and/or insulating material secured over them. Benches should be about 30 in (76 cm) high -much lower for large plants such as cymbidiums.

Free-standing greenhouses usually have a pitched roof or gable roof. There have been arguments for over 100 years as to whether these are best-oriented north/south or east/west. East/west will allow much more winter light through the roof at lower latitudes but may run hotter in summer.

Very often there is little choice of either location or orientation on a small section of land -the greenhouse has to be sited where it will conveniently go. Shading by buildings or trees is undesirable. Lean-to structures built against a solid wall or the side of a building can give quite good results. They should be against a more or less south-facing wall to get good day length. If your home has a sun-room getting good daylight hours you probably already have a “greenhouse”, which can be shared by people and your orchids.