Hi MissAnn. Here's what I know about peroxide (the 3% grocery store kind):
1. Peroxide is H202. Water is H2O. So peroxide has one more oxygen molecule than water. The second Oxygen molecule is unstable, so peroxide easily breaks down into water (H20) PLUS Oxygen (O). And it does so the minute it hits organic material (don't know why, tho).
Roots on all plants, but especially orchids, need a mix of moisture and oxygen to thrive. That's true of jasmine, gardenias, etc etc as well as orchids. Too much water in a pot will drive out all the O, and a plant's roots start to decline. That happens to a jasmine or gardenia in a pot when it rains nonstop for four days, or it's watered too often. Common as dirt in gardenia. Ditto orchids.
I've used peroxide both full strength (3%) or some dilution of it to water gardenias, jasmines etc that have had too much rain. Ditto orchids. When you pour it in a pot that's overwetted, you will see it bubbling. That's the Oxygen being released, so you can tell oxygen is now present at the roots where it wasn't before, and the plant has a better chance of escaping root rot.
2. I've used it on small gardener's wounds, splinters and the like, for many years. When you put it on a wound or splinter, it bubbles (the release of oxygen), and the bubbling can actually lift a splinter clear out so you don't have to do the needle bit, which I hate. So it does do a certain amount of wound-cleaning, floating splinters and dirt out of a small wound, tho I'm sure Drs have better things to use. Does it do damage to the tissue? I don't know. Usually if I have an infection, I just want to get rid of it quickly before it spreads, and the peroxide elps do that. I don't know if I would use it on an ear-lobe, given the caution. You wouldn't want a disfigured ear to put an earing in. But a gardener's hands and feet usually aren't a thing of beauty, so I would use it any time on them.
3. Some orchid specialists recommend using it to water orchids all the way from dilute to full strength (for the aerating reason in #1). I've done it from time to time with no damage whatever to the plants. Just the bubbling. But it gets really expensive if you have a lot of plants so I do it only very occasionally.
4. I haven't used it as a root soak or spray. I spray roots with a dilute physan 20 solution when repotting. It stops the bacterial activity that sometimes stops new roots from developing. It's not necessary to soak in physan 20 -- it's a contact anti-bacterial, anti-fungal. It works on contact, so spraying is enough. I soak pots in it for 24 hours before re-using.
That's all I know. Hope it helps
PS I use cinnamon on every cut on orchid leaves, stem, or roots. I've used it a few times when I dropped a phal and damaged a new leaf down into the crown. Stops any rot, and the damaged leaf grows out nicely without the crown itself being damaged. I also use it on sunburn or outher leaf wounds.
It's a good anti-bacterial, anti-fungal. It's also a dessicant, so it seals the wound somewhat to keep the bad things out. Don't use it on good roots (it's a dessicant)