LIGHT
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Most plants, including orchids, require light to perform photosynthesis. There are many kinds of orchids and each has a different lighting requirement due to where they live in their natural habitat. Some are exposed to a bright tropical sun while others live deep within shady forests. You need to learn what types of orchids you have and try to provide them with the same lighting levels they would normally receive in nature.

Light is measured in a unit called a footcandle (fc). A footcandle is equivalent amount of light that is produced by a candle at the distance of one foot. To give you an idea of light levels, on a clear sunny summer day at noon, the light in the sun would be over 10,000 fc. At the same time of day on a overcast winter day, the light level may be less than 500 fc.

You most likely will not be able to tell the true light level in an area because the human eye is too efficient at adjusting your vision to a broad range of light levels and can be fooled by the type of light present. For example, a grocery store may appear brightly illuminated with florescent lights, but in reality, the light level may be as little as 500 fc. To determine the light level in the location you want to grow your orchids, you will need a light meter that will give you readings in footcandle units and is capable of measuring bright light up to at least 5,000 footcandles. You can also determine the light levels at a location by using the built-in light meter of a SLR-type camera using a special table:

SLR CAMERA LIGHT MEASURING TABLE

IF you do not have a light meter or any other way of measuring light levels, here is a very rough rule of thumb you might follow:
Full Sun: Direct sunlight that's unobstructed for six to eight hours a day.
Partial Sun: About four hours of direct sun a day or lightly shaded sunlight all day.
Partial Shade: About two hours or less of sunlight a day.
Filtered Sun or
Broken Shade:
No direct sun, but some filtered light.
Dense Shade: No direct sun at all.

- - TOO LITTLE LIGHT - -

How do I know if I am not getting enough light?

If your orchid is showing any of these signs, chances are it is not getting enough light.

  1. Dark green leaves with no luster to them. The roots system is fine.
  2. Each new growth is smaller than the last growth.
  3. Your orchid is floppy and very weak looking.
  4. It has not bloomed or it has very few blooms.

How can I increase my light?

You need to move your orchids into a better light source, a different window, open the curtains, remove objects that maybe shading the window such as a tree or awning.
Be very careful when introducing you orchid (or any plant, for that matter) to more light because a plant that has been in poor light for any length of time will have very delicate leaves that can burn easily. Move your plant to a higher light level gradually over several days. If you notice the plant leaves burning (they will turn brown and be very dry), move the plant further away from the light source or provide some shading for a week or two until the plant gets used to the increased light.

If you are growing your orchids under electric lights:

  1. Reduce the distance between the light and the plant.
    NOTE: If you are using incandescent lamps, be careful not to place the plants too close to the hot light.
  2. Move the plant toward the center of the light.
  3. You should operate your lights 14 to 16 hours a day.
  4. Make sure the bulbs are not over a year old, older bulbs tend to give out less light.
  5. Use a special "grow light" in your fixture.

- - TOO MUCH LIGHT - -

How do I know if I am getting to much light?

There are several ways you can tell if your orchid is getting too much light:

  1. The leaves are showing burn spots. The spots can be yellow or brown dry patches on the leaves. They could also be rough and slightly raised.
  2. The leaves feel hot to the touch. Leaves should be cool to the touch.
  3. The leaves start turning black and dropping off. A plant exposed to too much sunlight will eventually die.
  4. The plant's growth is stunted and the leaves start to turn yellow.
  5. On some orchids, the color is bleached out of the leaves.

How can I reduce the amount of light?

This is easier to control than not enough light.

  1. Move the plant away from the hot sun. Remember that the sun coming thru a window and maybe intensified by the glass.
  2. Afternoon sun is also much "hotter" (brighter) than the morning sun, so move the plant to a East-facing window.
  3. Place shear curtains in front of the windows.
  4. Provide shade if growing out doors. A plant that may be fine in the spring but could get burned as the sun moves higher in the sky toward summer.

If you are growing under lights, you usually don't run into this problem unless you leave your lights on all the time or the lights are too close to the plants.

Typical lighting requirements for the most commonly sold orchids:
Phalaenopsis 1000-1500 fc Never exposed to direct sun light.
Paphiopedilums 1000-3000 fc Expose to only early morning sun.
Miltonia 1000-3000 fc Keep in diffused light.
Odontoglossums 1500-2000 fc Expose only to morning or evening sun.
Cattleyas 1500-3500 fc Give plenty of light without burning their leaves.
Vanda 1500-4000 fc They like strong light, full morning sun.
Oncidiums 1500-4000 fc Same as above.
Dendrobiums 1500-4000 fc Same as above.
Cymbidiums 7000-8000 fc Give as much light as possible without burning the leaves. Provide lower light (2000-3000 fc) when flower spike appears.
NOTE: there are species in these genera that may require different light levels.

What orchids Need
Water | Light | Temperature | Fertilizer | Humidity | Air movement

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