Hi, Bob. I used peroxide on some tropicals over a period of years. I have used it on orchids, mostly in the winter or after a week or so of rain.. Usually I just put it in the watering water each time for a couple of weeks. Mostly, it just gets too expensive to use it constantly

I have used it full strength, half water half peroxide, and other mixes down to a couple of glubs in a gallon of water, depending on what I thought the medium/plant needed. The glub-glub per gallon was for regular watering. The higher concentrations was for definitely water-logged media. This is on both tropicals and on orchids. Definitely no harm done.

Is there a measurable benefit? It would take a controlled experiment, which I'm not equipped to do. It does oxygenate the roots in water-logged medium. You can see the bubbles as the peroxide works its way thru the pot. I couldn't tell you if there's some other benefit.

I keep it around, and mostly use it for a couple of weeks in only problem situation. It's too expensive to use constantly. However, if I thought a plant needed the boost, I would use it each time I watered for a week or two.

However, I don't think you need it as a preventative unless a problem arises and you suspect rot, or find a poorly-draining pot. It's expensive to use often on a lot of plants. There's no harm from it so you can use it on a few plants and draw your own conclusions.

If you do try it, I hope you'll update this post and let us know what you think.

Here's a link to a site with orchid tips on many subjects gleaned from old Orchid Digests and other such sources.

If you scroll down you will find a heading about using 2 teaspoons of Physan per gallon of water once a month as a rot preventive. You can also use it as a spray if the crown of a plant gets wet.

I've been using that on teenies and rootless and it seems to work.

Here is a link that might be useful: Harvey's Orchid Notebook

I don't use it except at full strength on a cut. It loses strength really quickly when exposed to light. And right out of the bottle it is not that strong to begin with.

Thanks guys, I'll try it on a few plants and see what happens.

I get my peroxide from the dollar store. I use an ounce to a gallon once a month when I use my plain water drench, and I also use it full strenght for cuts and other assorted ailments, much as mehitabel does.

I have used H2O2 on our commercial orchid crops with great success, preventing bacterial, fungal and algae problems. It is also great for getting rid of insect pests, slugs HATE the stuff. Use 3% directly on the plants, try to avoid it on the flowers and buds as it can damage these due to these parts of the plants being a bit more sensative. You can dip the pots right into the 3% solution for root problems, it's GREAT for getting rid of algae deposits on the roots of vanaceous plants. We buy ours in a higher solution then the store bought 3%, but we do dilute it to 3%. So what you buy in the drug store are all you need
do not dilute further. Peroxide may burn some root tips, though nothing major. I find that if any root tip burn occurs, usually in about 2 weeks a new flush of root tips are produced.
Good luck
John

First and foremost, hydrogen peroxide dissociates into water and oxygen when combined in water and in the presence of light, dissociates as well. For the chemists:

2 H202 --> 2H20 + 02

That being said, orchidguy is correct, that any further dilutions would most likely be a waste of time...although it makes sense as an algicide straight from the bottle.