Welcome to the AOS Beginner�s Newsletter. We will be sending you monthly tips on how to grow orchids and help you get them to bloom again. In addition to the information presented here, we invite you to visit the AOS website at www.aos.org and check out the information found under ORCHID INFORMATION > ORCHID BASICS.
Why won't my orchid rebloom ?
Insufficient light is the most common cause of failure to re-bloom your orchid. Leaf color indicates if the amount of light is adequate. The lush, rich, dark green of most houseplants is not desirable in orchid leaves. A grassy green color (light or medium green with yellowish tones) means the plant is receiving sufficient light to bloom. The orchid on the left shows the correct leaf color and is producing abundant blooms, the plant on the right has dark green leaves and no flowers. Orchid plants need sunlight. Light is used to turn moisture and nutrients into plant growth. A good rule is to give your plants as much light as possible without scorching. While too much light may damage the plants, too little light will prevent flowering or cause weak growth.
Too much sunlight is indicated by scorched spots on the foliage or pseudobulbs where the sun hits directly. Rarely does sunburn discolor an entire plant, only the portion of the green parts that is hit by direct sun for too long a period. Increased light should be given gradually. Burn damage is caused when the plant tissue gets too hot. If a leaf feels hot to your fingers, it may be burning. If you can cool down the leaf temperature with moving air and water, then the light can be brighter without doing any harm.
Morning sun is more beneficial to plants than afternoon sun. Therefore your growing area should be located to get maximum sun and light early in the day. A windowsill chosen for orchids should face east or south.
For more detailed information on the light requirements of specific orchids, you should consult the
AOS cultures sheets.
Although there are light meters that can be used to measure the light in your orchid growing areas they can be confusing to use. An easy way to determine the brightness of your growing area is to use a white sheet of paper or white illustration board or
foamcore. Hold your hand about 8-10 inches above the white card on a bright day when the sun is shining fully. Use the illustrations below as guides.
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Notice the dark shadow with a hard edge.
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Shadow has a soft edge and is somewhat lighter. Appx. 35-40% shadecloth.
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Soft edge, open shadows. Appx. 50-60% shadecloth
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Very soft, grey shadow. Appx. 70% shadecloth
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Blurry, indistinct shadow - difficult to recognize the object
in the shadow.
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Greg Allikas
November 2009
Did You Know?
An orchid seed pod can contain tens of thousands - even hundreds of thousands of seed? In nature, when a capsule becomes ripe and splits, thousands of seed are dispersed through the air. With so many seeds, it would seem that orchids should be found everywhere. But, in order for a seed to germinate, very specific conditions must be met. As a result, the percentage of seeds that actually grow may be very small.
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