Jewel Orchids in S/H?

[kerokero]

I mention planting on top of the LECA mainly because it's more natural for jewel orchids (rambling branches on the surface of the ground), and thus the stem likes a different environment than the roots - namely more air flow and less direct contact with water. Placing the stem on the substrate and haivng the roots grow down into it is how they like it, and keeps stem rot from being an issue. Once the roots have grown down into the LECA, keeping them covered isn't an issue, it's just for the phase where it's rooting. The roots LOVE the air pockets and humidity of the LECA, but I've still had some rot issues when I put stem pieces into the LECA, they rotted up to the part that was above the LECA - not always but it still occurred where it doesn't when the stem is just sit on top (this is true of most substrates as well). The stem and leaves like it humid, the roots can take it wet, and the LECA still counts as a relatively wet environment.

"but one would assume it is getting plenty of air placed in hydroton? if they can sprout completely under water, they are certainly getting more air placed into LECA."

There is more air in the LECA that you'd see in most substrates, but you're also keeping the stem in contact with a wet surface (the wicking LECA) constantly and I believe this is where part the rot issue comes from. The less contact the stem has with wet surfaces (sitting on LECA is way less than in LECA) seems to be key, as well as the fact that while there is more air in the LECA, this does not mean there is air flow in there. It still amazes me how much of a difference it makes if the air is able to move - especially with orchids. You can have 80+% humidity, but if it is not moving, how many orchids on this board would develop rot?

Don't take a plant's ability to root in water as any indication of when they will or won't rot. I don't know what it is, but for some reason most plants will root in water, but if you swap that out for a high humidity environment instead, many will just rot.

[Rivka]

that explains it wonderfully, thank you for taking the time. i will change them right away. it is all about how they like to grow in the wild isn't it, just like with all the rest of our 'chids.

can you tell me anything about pot size? is this something that i should have in many small pots (i have 4 cuttings) or is it ok to use one large one since the LECA does not have the uniformity issue that bark and things have?


as for the pondering as to why something can root in total water and rot in a just very moist place, is clearly the addition of air, most anaerobic bacteria that cause rotting need both, so in fact the complete water coverage provides some level of protection.
a cool place you also see that is with ship wrecks, they last hundreds of years under water but must be left there, because the moment they get touched by air, they quickly start to decompose!