When orchids die from overwatering, it isn’t really the result of too much water. It’s actually caused by too little air. There’s just so much open space in any potting material, and water naturally displaces air, so if you apply it too often, there’s no room for air. And your orchid needs air for healthy root growth. If it doesn’t get enough air, the roots rot and die.
Ironically, just as overwatering is a big killer, so is underwatering. In this case, the lack of water leads to root damage by dehydration
Because orchid potting material drains much more rapidly and tends to hold less moisture than materials commonly used for other plants, some people tend to underwater. Also, remember that the fresh potting material dries out much more quickly than older potting material does.
Too Much Light or Heat
Light and heat are related to one another. Frequently, excessive light leads to high temperatures. When the orchids receive too much light, the heat starts to build up inside the leaf. Think of the orchid leaf’s skin being like a plastic bag with very small holes in it. Inside of this plastic bag is the interior of the leaf. When excessive heat gets trapped inside the leaf, it literally cooks and destroys the leaf plant tissue. Large black circular dead spots form, or in extreme cases, the entire orchid collapses. After this damage is done, you can’t do anything about it.
When the orchid is in full illumination, feel the leaf surface with your hand. If it’s hot to the touch, move the orchid to where it gets less light.
Leaving Orchid Foliage Wet Overnight
Leaving orchid foliage wet overnight is asking for trouble in the form of leaf spots and crown rot disease. (The crown is the growing point of the orchid.) Water your orchids in the morning or early afternoon, so the leaves have plenty of time to dry before nightfall.
If you can catch these diseases early, you may be able to save the orchid. But after the disease (which shows up as soft, mushy tissue, that eventually turns black) gets to the growing point of the plant, it’s good-bye for your orchid.
Too Much Fertilizer
Fertilizers are salts, and salts, in concentrated form, are types of herbicides (plant poisons). Applying too much fertilizer will dehydrate the orchid roots. Signs of too much fertilizer are black root tips or black or brown leaf tips. So, when you fertilize, be careful not to apply more than the recommended dosage, and only use a fertilizer when the plant is actively growing and when the growing media is damp.
Improper Use of Pesticides
When pesticides are used properly, they’re safe for both you and your plants. However, if they’re applied at too high of a concentration or applied when the plants are dry or the air temperature is too high, severe damage to the orchid plant can result.
Also, many pesticides are dissolved and mixed in with a type of oil, which in and of itself can cause leaf damage, especially if the material is applied in bright, hot sunlight.
So use care with these materials and always read the label before applying the chemical.
Catching insect problems in the early stages is very important. If you realize that your orchid is completely covered with an insect like scale or mealybugs, getting rid of all of them is very difficult.
Sometimes trashing this plant for the sake of others in your collection is the best approach; you don’t want to expose your other plants to these critters. For more information on common orchid pests and their control.
Purchase of Sick Plants
Some orchid growers are Florence Nightingale types who feel it’s their mission to save an orchid that looks sick. So they buy it, usually at a great discount. In most cases, these orchid lovers don’t get a “deal” at all.
I highly recommend you resist the temptation to buy an unhealthy orchid and try to nurse it back to health. If an orchid is in poor condition and the leaves are wilting or shriveled, it’s usually on an unstoppable death spiral and the likelihood of your bringing it back to robustness is slim to none.
Poor Water Quality
In certain parts of the country, notably in the West, some local water has a high salt content, which can be very damaging to orchids. It can cause the same problems as overfertilizing (see “Too Much Fertilizer,” earlier in this topic).
If you have any doubts about the quality of your water, have a water test done by a company that tests water for drinking quality. Also, don’t use water that has been treated with a water softener on your orchids. It usually contains a high amount of salt.
Orchids don’t appreciate stale air. When air isn’t circulated, fungi and bacterial diseases flourish. Moving air also evaporates moisture on leaves (moisture on leaves is another cause for disease problems). So make your orchid happy and invest in an overhead ceiling fan or oscillating fan to keep the air gently moving. It will make a great difference in the health of your orchids.
The Ten Most Common Ways Orchids Are Killed on what-when-how, In Depth Tutorials and Information
(www.what-when-how.com/orchids/the-ten-most-common-ways-orchids-are-killed/) if that fails, try (www.web.archive.org/web/20140720070004/hxxp://what-when-how.com/orchids/the-ten-most-common-ways-orchids-are-killed/) replace "xx" with "tt", )
By Steven A. Frowine
(www.what-when-how.com/steven-a-frowine/) or (www.members.authorsguild.net/stevefrow/bio.htm)
Other works by Steven A. Frowine
Miniature Orchids (www.members.authorsguild.net/stevefrow/miniature_orchids_77055.htm)
Fragrant Orchids: A Guide To Selecting, Growing, And Enjoying (www.members.authorsguild.net/stevefrow/fragrant_orchids__a_guide_to_selecting__growing__and_enjoying_38984.htm)
Orchids for Dummies (www.members.authorsguild.net/stevefrow/orchids_for_dummies_38975.htm)
Moth Orchids - The Complete Guide to Phalaenopsis (www.members.authorsguild.net/stevefrow/moth_orchids__the_complete_guide_to_phalaenopsis_65954.htm)
Growing Tropical Slipper Orchids Under Lights (.pdf file free to download)(www.members.authorsguild.net/stevefrow/growing_tropical_slipper_orchids_under_lights_121823.htm)
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