Discussion
The most important thing you can do for your orchid is to give it the correct amount of light for its genus. Remember the photosynthesis reaction from last month’s lesson? The driving force, catalyst, for this reaction is sunlight. Let’s take a closer look at how plants harness the energy of the sun to produce the carbohydrate they need to grow and bloom.
Plants produce a green pigment called chlorophyll. Chlorophyll, located in the chloroplasts, absorbs the radiant energy (light) from the sun. This light energy triggers a chain reaction that converts water and carbon dioxide into glucose and oxygen. Ever wonder why plants are green? That’s because the chlorophyll absorbs the light on the blue and red end of the light spectrum and reflects the light on the green end. We see the reflected light.
The orchid stores the glucose for later use in plant maintenance and blooming. Orchids will preferentially use their stored glucose for plant maintenance, which includes growth and tissue repair. If there is extra glucose left over, it will be used for blooming. This means that if the plant has not made enough glucose for plant maintenance and blooming, it will not bloom. So, if you have an orchid that has been growing but never blooms, one of the reasons for this could be that it’s not getting enough light to allow it to produce sufficient glucose to do both.
A Phalaenopsis orchid is the usual choice for a beginner orchid grower. One of the reasons for this is that it’s very easy to meet the light needs when growing indoors. Phalaenopsis will grow in any bright window such as an east- or west-facing window. In northern latitudes, they may need be grown in a shaded south-facing window. This genus of orchids also grows very well under lights that are about 1-2 ft (30-60 cm) above the plant and emit greater than 10,000 lumens per square yard/square meter.
Finally, remember that each genus of orchids has its own light requirements. Before you buy a new orchid, make sure that you can provide the required amount of light for its genus.
Fun Fact
If you are observant about the color changes in the leaves of your orchid, it will tell you if it needs more or less light. When you buy a new orchid, make a mental note of the color of the leaves. How green are they?
When an orchid is not getting enough light, it will produce more chlorophyll to try to use more of the available radiant energy. This causes the leaves to become darker green. This also means that the plant will probably not be able to make enough glucose for blooming.
Conversely, if the orchid is getting too much light, it will remove chlorophyll making the leaves a lighter shade of green or yellow. This is a much more serious problem for your plant because excess radiant energy in the leaf will be dissipated as heat. The heat can scorch and kill the leaf and eventually the entire plant. Sometimes, you may notice the leaf “sunburning” and turning red before it begins scorching. If this happens, immediately move your orchid to a less sunny location.
Website Tip
One of the great resources available on the AOS website are the Orchid Care & Culture Sheets. These can be found under the “Orchid Care” tab, “Orchid Care Basics” sub-tab. This page houses detailed care sheets for 18 of the more common orchid genera.
Included on each page are photos of representative orchids in each genus, instructions for light, temperature, water humidity, and fertilizer requirements, tips for repotting, and additional resources. These should become your “go-to” place on the website for orchid care information.
Resources
1. Orchid Care & Culture Sheets - Orchid Care & Culture Sheets - American Orchid Society
2. “Evolution of LED Lighting and Orchids” – Kelly McCracken – Webinar - Evolution of LED Lighting - American Orchid Society
3. “All About Orchids” website tab, “Orchid Care Basics” sub-tab, “Light Conditions” - Principles of Light - American Orchid Society
4. “Light Up Your Orchids” – Howard Zoufaly – American Orchid Society Bulletin – December 1986 - ORCHIDS Magazine
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