Thoughts on re-using bark and sphagnum ?

[orchidsarefun]

Has anyone tried to re-use bark and sphagnum ?
Some orchids ( like catasetums ) are potted up annually. I spread any "old" bark and moss that I have after repotting, on the garden as a top-dressing, but wondered if I washed it/left it in the rain to leach out salts etc, if it would be good for re-use ? Especially with longer-lasting bark like orchiata ? I have noticed too that a lot of the regular bark from last year that I spread on my veggie beds still looks OK.....
I might try it this year, wouldn't do it more than 2x but in theory you should be able to do so until you see visible deterioration in the bark. If sphagnum can spend years in the "wild", then surely the same principle would apply ?

[Ray]

Keep up with the "garden addition" mode. An extended exposure to rain and sun will not sufficiently remove absorbed minerals and plant wastes, will harbor even more pathogens than they had previously, including new ones your orchids have not seen, but worst off all, the exposure will hasten its decomposition, meaning that it will become a root-suffocating sludge much sooner in that second cycle.

[MattWoelfsen]

This is a concern I have about re-using potting material. When I repot, I place the old media in my garden, like you have done for your old media. I did think that I could re-use old media in my new pot, after I washed it out--like I do with pots. But then I got to thinking, how much time do I want to spend washing and leaching the old stuff? Would I be 100% confident that I've eliminated chemical residue, pests, and other maladies that I might transfer to the new plant?

My conclusion: not worth my time and certainly not worth the effort I would go through trying to eradicate any pests that my new plant would experience as a result of re-using old potting media. I spend too much money on orchids to take that kind of risk. Ironically, my garden plants seem to be doing okay with the old stuff.

[Brooke]

Reusing old media would be a great way to spread a virus. Would it be worth it if you contaminated another plant?

Sphag in the wild is growing and not dehydrated.

Brooke

[quiltergal]

Why bother repotting at all?

[AnonYMouse]

S'why I use as much straight inorganic material (LECA, lava rocks) as I can

[galgoa]

What is your opinion about sterilizing with microwave oven?

[orchidsarefun]

Originally Posted by quiltergal

Why bother repotting at all?

Some orchids I have are overwintered bare root....

Surely a bleach wash will kill any viruses in the bark ? Works for pots. I think I may just experiment if the bark seems as good as new. I have had people tell me that some orchids they have haven't been repotted in years, me using bark 1x, after due disinfecting is not going to be the end of the world.

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[dounoharm]

when you only have a few plants, repotting every year is fine, but when you have a greenhouse full, you repot some everyday and STILL never catch up, lol....a lot of my greenhouse plants go a couple years in the same media...I tried to be more regular with the ones in fine media like paphs...but cattleyas usually go 2 years for me....only buy really good hard fir bark and you will be fine.....leftovers after repotting ONLY go in the garden....I do not recommend trying to reuse it!

[Orchid Whisperer]

Originally Posted by galgoa

What is your opinion about sterilizing with microwave oven?

If you are 100% certain that a material has never contacted plant material that could transmit a virus, you could try a microwave to deal with some bacteria and fungi only. Some fungi and bacteria may not be killed by microwave temperatures. I can really see this as an option for only non-porous, non-metal tools that will not melt (and there are few of those that I use with orchids). Growing medium would probably dry out and catch fire before it stayed at high enough temperature to be sterile.

For viruses, you need to keep what you are sterilizing at high temperature (I have heard 300F) for an extended time to achieve sterilization.

You can use bleach to sterilize non-porous tools. Sodium hypochlorite in bleach is a powerful oxidizing agent, and oxidizes organic material that it reacts with, presumably including fungal and bacterial cells an viruses. It will not fully penetrate into porous growing medium, or fully leach back out, so I would avoid using bleach to sterilize organic growing media.