The Basics of Orchid Culture

By Steven A. Frowine

Editor's Note: This is the 8th of a 10 part series of articles about orchids. These articles are written by Steven Frowine, who collaborated with National Gardening Association and Wiley & Sons to produce the highly popular book Orchids for Dummies. We hope you enjoy this series of articles!  

Orchids are not difficult to grow. 

But, like all plants, they have certain needs that have to be met so they can perform their best. I will now discuss orchids' most fundamental requirements and the simplest, most effective ways to provide them, based on my over 40 years of experience growing them in my windowsills, under lights, and in a greenhouse.

If you put a little effort into modifying your growing environment to help your orchids feel at home, it'll pay off in healthy plants that provide plenty of flowers.

Light is essential for all green plants, including orchids. Light, along with water and carbon dioxide, are the raw material plants use to produce their food. Providing enough light is the most challenging requirement for indoor gardeners in areas of the country like the Northeast and the Midwest, with short days and low light during the winter. Fortunately, plenty of species and hybrids of orchids don't require super-high light intensities and so are more suited to these climates.

If you're blessed with naturally high light — like the kind found in Hawaii, California, and Florida — you can grow both the high- and the low-light-intensity orchids. You just have to use greenhouse shading or light-reducing draperies to satisfy those orchids requiring modest amounts of light.

Light Fundamentals

Orchids are traditionally categorized by their light requirements — high, medium, and low. You can easily grow orchids in the low to medium categories under artificial lights or in bright windowsills. From a practical point of view, the orchids with high light requirements are most successfully grown in bright greenhouses.

Greenhouses: Your high light source

Greenhouses, like the one shown below are the most efficient collectors of natural light.

The amount of light penetrating the greenhouse is determined by the glazing material used, its geographic location, how it's sited on the land, and whether it's shaded by surrounding trees or a commercial shading compound or fabric.
The greenhouse option is the most expensive, but you don't have to own one to grow most of the orchids in this book.

High-quality greenhouse setups provide shading and efficient use of space to accommodate as many orchids as possible.

Windowsills: Not all windowsills are created equal
Windowsills are the most readily available and cost-effective source of light. The amount of light windowsills can provide is primarily determined by:
* The size of the windows
* Whether there is an overhanging roof: This can make a difference in how much light will actually reach the plants.

The extent of the roof overhang will make a difference in the amount of light they will receive and what time of the day the orchids will receive it.

* How far back the windows are recessed: Bay or bow windows expose the plants to more light than other types of windows.

Bay windows increases the size of the growing area and the amount of light the plant receives, because light can penetrate from multiple angles.

* The direction the windows face: Whether the windows face north, south, east, or west make a big difference in the amount and quality of light the orchids will receive.

South-facing window: This is the brightest window so offers the most possibilities. It's an ideal location for those orchids that demand the strongest light. You can place most of the other less-light-demanding orchids a few feet back from the window, or you can diffuse the light from the window with a sheer curtain. Note: This exposure can get hot, especially during the summer.

East-facing window: This window offers morning sunlight, which is bright but not too hot. During the spring, summer, and fall, this is usually an ideal exposure for most orchids in this book, except those that require extremely high light (like Vandas). During the short, dark days of winter, many of these same orchids usually prefer a south-facing window.

West-facing window: This window receives as much light as the east window but, because it's afternoon light, it's much hotter — so this isn't as desirable a location as the east-facing window. If you need to use a west-facing window, make sure your orchids don't dry out too much because of this increased heat.

North-facing window: A north-facing window simply doesn't provide enough light to sustain the healthy growth of orchids. Use it for low-light plants like ferns.

* How far the plants are placed from the windows

* The age and condition of the glass: Tinted and reflective glass can dramatically reduce light intensity, so it's usually not recommended. No matter what kind of glass you have, keep your windows clean, especially during the winter whenthe light intensity is low, so your orchids will receive as much light as possible.

* The time of the year: During the winter, the sun is lower in the sky and the day length is shorter. The opposite is true during the summer. As a result a south-facing window may be fine for certain orchids during the winter, but you may have to move the orchids to an east-facing window during the summer.

Different types of orchids have varying light requirements because they naturally grow in a wide range of habitats. Some thrive in full sun on exposed rocks, while others are at home in dense jungle shade.

Those with very tough, thick, stout, and sometimes narrow leaves frequently are adapted to very high light intensity. When the leaves are softer, more succulent, and wider, this is usually a clue that they're from a lower-light environment.

The type of leaves indicates an orchid's light requirements.

Your orchids will tell you by their growth habits and leaf color if they're getting adequate, too little, or too much light. When orchids are getting enough light, you'll notice the following:

* The mature leaves are usually a medium to light green.
* The new leaves are the same size or larger and the same shape as the mature ones.
* The foliage is stiff and compact, not floppy.
* The plants are flowering at approximately the same time they did the year before.

One of the most frequent results of inadequate light is soft, dark green foliage with no flowering. Another symptom of inadequate light is stretching, where the distance between the new leaves on the stem of orchids like Paphiopedilum, Phalaenopsis, or Vandas are farther apart than with the older, mature leaves. On other types of orchids, the new leaves tend to be longer and thinner.

Notice that the long distance between the leaves on the stem causes a ladder effect. This is the result of insufficient light.

When orchids get too much light, their leaves turn a yellow-green color or take on a reddish cast and may appear stunted. In extreme cases, the leaves show circular or oval sunburn spots . The sunburn is actually caused by the leaf overheating. Although, in itself, this leaf damage may not cause extreme harm to the plant if the damage is isolated to a small area, it does make the plant unsightly.

A Paphiopedilum leaf with a round or oval brown spot caused by too much light or sunburn.

If the sunburn occurs at the growing point, it can kill that lead or the entire plant. Higher light intensities than are usually recommended are possible with some orchids if you increase the ventilation to lower these elevated leaf temperatures. Some orchid cut-flower growers like to push their orchids with the highest light intensity they can take without burning to yield the maximum amount of blooms. However, for most hobby growers, I don't recommend this.

If you don't have adequate natural light to grow orchids well, stay tuned. The next blog will tell you how to grow plants entirely under artificial lights.

This useful reference, Orchids for Dummies, which has been popular for both beginner and experienced orchid lovers, is available on and in book stores around the country.

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