Air Management

[Ray]

There's a new story entry added:

Air Management

"Air management" is probably the single, most significant aspect of orchid culture, but a subject that is usually never directly addressed in discussions about how to grow them. Let's start with the basics: Orchids, for the most part, are epiphytes - "air plants" - growing attached to trees or rock outcroppings, or in the leaf litter on the forest floor, and have their extensive root systems rambling around the surface, where they are exposed to lots of air. They are not parasites, but have evolved to the point of not needing a soil medium from which to take nutrients, instead gleaning their existence by absorbing their water and nutritional needs primarily from nutrient-bearing rainwater cascading on them from the canopies of the forests and jungles in which they live. One of the more observable aspects of that evolution is the water-storage mechanisms of the plants, such as pseudobulbs or thick, fleshy leaves, and the development of the sponge-like layer of cells on the root surface, the gray or silvery velamen that turns mostly transparent when saturated, showing the green inner cells of the root. Another part of that evolutionary development, but one we tend to ignore, is that of gas exchange.

[Tindomul]

Excellent article!! It really teaches you about why the plants need to be given air around the roots, and how to do it. Thanks!!!

What are your thoughts on sphagnum moss. I currently have two phals potted in this. One has grown its roots outside the pot, and the other hasn't yet. In both cases it takes more than a week to dry out the sphag. Should the plants be rewatered when the sphag is completely dry, or should they be rewarted when dry but still moist to the touch??

Thanks.

[Piper]

A very nice post, Ray!

Except for my Catt alliance babies, I pot most of my critters in NZ sphag. I was repotting many of my Paph and Phrags this spring and noticed that those potted in clay had nearly twice the root mass and twice the growths of those in plastic.

The watering certainly wasn't the issue. I'd water each pot when the sphag reached a certain dryness. Some have suggested that it's the evaporative cooling keeping the roots from cooking in a hot sun that contributes to the extra growth. That could certainly be the case, but I think the breathability through the pot itself is also a huge factor. Water molecules are big and globby. If they can get out, air can easily get in.

And while constant watering is a pain, I've found my best growers have had the best air access. So thanks for addressing this oh so critical point of culture, Ray!

Julie

[Ray]

Sphag is a potentially tough potting medium, and one in which the quality (species) makes a huge difference! The 5-star NZ stuff is by far the best, being nice and fluffy, and staying that way for a fairly long time.

I find that mising something "springier" with it helps - I usually use coconut husk fiber.

Otherwise, you have to go one of two ways: pack it loosely when repotting, water it normally, but keep an eye on it for compression, or pack it fairly firmly, and then just barely moisten it when you water, so it won't compact any further.

Interestingly enough, if you have species that a very slim in their nutritional needs, that is, they can handle a lot of pure water only, sphagnum will grow from spores, and living sphagnum stays naturally airy.

[Anyara]

Really enjoyed your informative article!

As to Spaghnum, I used to have a tendency to kill or seriously maim anything I planted in spaghnum bit I think I now know why...I had stared adding medium aliflor to it and keeping it loose in the pot and that seemed to help considerably - some support for your article on a practical level. More air at the roots!

Thanks again for the insights!

[intoorchids]

Thanks for the excellent article. I am new at growing orchids and found this to be not only very informative but very important. I truly enjoyed your article and want to thank you for putting it in terms that even a beginner can understand. I use coconut hulls, carbon chunks, perlite mixture. I have some orchids that came in a fir bark mixture but I will switch those over to a coconut husk mix. I am also trying Aussie Gold which is a diatomacious stone mix (super secret of course). The plants seem to be doing quite well in this mix and are producing new growth and nice roots. I use plastic cone pots (air cone) with the sides and cone having multiple slits in them for air movement. I like them because of the air movement and I can also see root developement. Thanks again and as you can tell I am a beginner and still learning.
intoorchids

[Oscarman]

Thanks Ray for a very interesting article.
As I read it I began to think about some Phals that I have and the differences of how they had been potted in NZ moss. Some tight, some loose. Some dry fast, some dry slowly. Some are light after watering, some weight a ton. Repotting is in order. Happy roots make all the difference!

[Randy]

Very good article. Here is a person who understands the botony of orchids and knows how to relate it to others clearly. Very well written!

Randy

[joliet]

Good day to you Ray, I have never read anywhere a more thorough and intelligently put information about the need for air in orchids. Thank you very much, Myriam

[cb977]

Can't believe I hadn't read this before now!
Wonderful bit of writing

This is exactly the type of information that our members are looking for: clear, concise and informative!

Can this article be printed in a club newsletter with your name and website listed?