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.
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Once More With Feeling:
How and When to Water Orchids 


In the December newsletter we provided a link to a short watering essay on the AOS website, and the subject has been mentioned a few times throughout these newsletters. But seeing as we are getting close to passing down the ultimate gem of orchid wisdom (the key so to speak), we thought it a good idea to really drive home the relationship between water and orchids. More orchids are killed by overwatering than by under watering. Here is an entertaining little essay that I found while prowling the web.

So how do you know how much water is enough, and when to water an orchid? Although plants cannot speak, they can tell you something about their adaptations to their environment just by the way they look. Compare the fat pseudobulbs of a species such as Catasetum tenebrosum with the pseudobulb-less leaves of Phalaenopsis schilleriana. Your first conclusion should be that those fat bulbs store water and nutrients (like a daffodil, iris, amaryllis or any other bulb) while the leaves of the Phalaenopsis would not be able to store nearly as much reserves. So those characteristics alone tell us that the Phalaenopsis comes from a relatively wet area because its leaves, although thick, cannot store water for long periods. On the other hand, the Catasetum must come from a dry area because it has the facility to store an ample supply of water. Take another look at the Catsetum. Notice that it is flowering from leafless (deciduous) pseudobulbs while behind those, are new leafy growths. What this observation tells us is that the Catasetum comes from a place that is seasonally dry. This orchid depends on its pseudobulbs to store water for an extended period, sometimes several months. During that time, there may be little or no rain. We can arrive at a rule of thumb from this discourse. Orchids with pseudobulbs should be grown on a wet-to-dry cycle whereas orchids without pseudobulbs should be kept evenly moist. This does not take into account any seasonal preferences a particular orchid might have, but applies to the growing season which is broadly, spring and summer, depending on the orchid and where you live.

Although these are very general rules that don't apply to every orchid, let's go over the preceding two concepts. A wet-to-dry watering cycle means that the orchid should be watered just before it is totally dry. Most Cattleya, Oncidium and Dendrobium hybrids will grow well on this kind of regime. How do you know when a potted orchid is almost dry? A dry pot feels lighter than a wet or damp pot. If it is a clay pot it will feel dry and not as cool as if it were damp. If the media is loose, you can poke a finger down into it to see how damp the media is, or use a pencil or bamboo stake or skewer. 

Keeping an orchid evenly moist means just that: not dry and not sopping wet, but damp. If you poke your finger into the media it should not come out with a film of water. Don't make the mistake of placing the pot in a saucer of water because that will keep the plant too wet. Phalaenopsis and Paphiopedilum hybrids will usually grow well on this kind of watering schedule. 

Orchid growers can adjust their culture practices to meet the needs of specific orchids and that will be the topic of a future newsletter.


Greg Allikas
February 2010

Resources

If you have missed any of the previous newsletters, you can find them archived by month right here. The Q&A'a that have been appearing on the homepage are also being archived and you can find those here.


ORCHIDS magazine upcoming features...

THIS MONTH
º New World Slipper Orchids, part 3
  Culture: What Nature Can Reveal
º Semi-alba Cattleyas
º Wardian Cases in Western Canada

left: Cattleya jenmanii 'Canaima's Lipstick'

MARCH
º Cymbidiums for warm climates
º Jewel Orchids, part 3
º Native Orchids: The Western Prairie Fringed Orchid

      send comments to - newsflash@aos.org


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