In the past I used it regularly to provide extra oxygen to the roots of indoor plants & to help with fertiliser uptake. I'm pretty convinced, from experience, that it works but I'd really like to know if anyone else has tried it?
It's got a multitude of other horticultural uses if you Google it! Though shy away from anything that claims it's a miracle!!! There are academic studies.
Maybe it's just that in Britain we've never really used it to sterilise things & associate it more with bad, yellow hair?!
I'll happily go on using it but it would be really interesting to get some more opinions? Google 'hydrogen peroxide for gardening', read about it & maybe try it for something?
It'd be a fascinating experiment on this site for UK gardeners?!

I used to use it in the water I soaked my daylily seeds in. But if the seed began to germinate and wasn't removed immediately, the root tip got burned and the seed ended up failing - a problem I haven't had since I stopped using it that way. Now I soak them for 24 hours in water that has a little hydrogen peroxide in it, and move them to water that doesn't for the remaining time.

Yes, getting dilution percentages right is the tricky bit. I don't know why I haven't used it lately but I'm definitely going to experiment (carefully) from now! It's cheap, I just bought 250ml of 9% dilution from my local chemist for £1.20 & while not organic it is pretty Green in use. Not sure how Green the manufacturing is...
The list of things it can be used for by gardeners is pretty impressive though!
My next experiment when I get a dry day is on my lupins. I've had to pressure spray the tender parts to get the aphid masses off & their tenacity has really affected the number of seed pods. Given a dry day I'm going to use a 2% solution in the pump sprayer & see if that spoils their fun more effectively...
Will post more with results.
This seems like a good source of sensible, slightly overenthusiastic, info on using HP in the garden:
https://www.using-hydrogen-peroxide.com/peroxide-garden.html

Try the food grade H2O2 , might be harder to come by though but it's a little more gentle .