Hydrogen Peroxide Uses for Gardeners

My first experiment will be on my aphid ravaged lupins in pots. The infestation was so bad that despite regular spraying with lightly soaped water from a high pressure pump spray they'd be massed again the next day on the tender parts. As a result my lupins barely produced seed.
Will I get better insect knockdown by using a 2% HP spray with tap water & no soap? Will HP damage the plant?
Guess I'll find out by doing it...

This seems like a sensible, though more enthusiastic, site that gives good info:
https://www.using-hydrogen-peroxide.com/peroxide-garden.html

My aunt used peroxide in her hairdressing salon. I can smell it now.
I've never heard of it being used on plants. I hope it works.

I've been using it to water my daylily seeds. The 3% type from the chemist. It's supposed to keep away any bacteria. Quite a few people recommend it with regard to germination of seeds.
We'll see if it works.

I read about it some months ago and was so impressed I bought four bottles! However they are still in their original wrapping because Life intervened. I must read up about its usage now.

Thanks for this - I have looked it up and it seems it might help powdery mildew
I have a real problem with this on my Penstemons so I think I will give it a try as below.

How to Use Hydrogen Peroxide to Kill Powdery Mildew
By Joshua Duvauchelle

Powdery mildew doesn't just give your plant's foliage a dusty white look; it can stress and kill your plants if it's not controlled. Caused by fungal spores, the mildew can quickly spread from infected plants to the plants beside it. Although powdery mildew can be controlled quickly and effectively with commercial garden mildewcides, those interested in natural home remedies can mix their own mildewcide from over-the-counter hydrogen peroxide.

Step 1
Remove any heavily infested plant foliage and stems that have wilted because of the powdery mildew. Cut off the foliage with a sharp pair of scissors or garden shears and discard them in a sealed plastic bag. Do not shake the foliage, in order to avoid spreading the mildew's spores.

Step 2
Pour a quart of standard 3 percent-strength hydrogen peroxide--available from most drugstores--into a gallon-sized spray bottle. Add three quarts of water and shake the spray bottle to mix its contents thoroughly. If you're using a bigger or smaller bottle, adjust the measurements so you're mixing one part hydrogen peroxide and three parts water.

Step 3
Mist the hydrogen peroxide onto your plants, focusing on areas that have powdery mildew growth. Coat the foliage until there's so much moisture that it beads and drips off of the leaves.

Step 4
Repeat the hydrogen peroxide application once daily until the powdery mildew problem subsides. Then, apply it as needed to control any new powdery mildew growth.

I use it as a mouth rinse, after I brush. It gives you a bright white smile...also for my plants.

This sounds great. I will take note, Darren.

Glad people are finding it interesting! & thanks for all the comments, I could almost stop writing it...
If anyone knows of any useful ways to work out dilutions reasonably accurately it'd be a relief for my addled grey matter

as a biologist I see it as a harmful by-product of cellular activity. cells have an enzyme to specifically break it down in to harmless water and oxygen. it does decompose into water and oxygen quickly but cells have to do it even faster.
we used it in the labs and it was bought as per volume [20vol being the most concentrated we could buy] and not as a %.
Splashes on the skin resulted in white blemishes that were itchy. so if you do intend to use it please be careful and wash off any splashes especially take care with your eyes.
I have memories of my mum using a dilute solution from the chemists to clear ear wax from my brother's ears!

That's good advice Seaburn. I've experienced those spillages! It looks like water then you get a sort of frosting on your skin which itches & then gets increasingly sore. Anybody experimenting with it should know that at high concentrations it's highly corrosive, if you splash yourself rinse under running cold water IMMEDIATELY!
As a biologist can you point me to anything useful for calculating dilutions? E.g. as my first experiment on aphids I used 5ml of a 9% solution added to 500ml of tap water. Is there an online calculator, chart or equation I could use so that I know the strength as a final percentage? Most H2O2 dilution calculators online assume that you're starting with 35%. Not sure my local pharmacy sells that...
Always appreciate your feedback, especially on this subject!

3% does the job for me

as I said we bought it in at 20 vol strength then we worked from that but we didn't use it on living tissue. so my honest answer is I don't know.
perhaps a pharmacist can help. how % relates to strength in vol I don't know. never needed to. just knew how to use it in experiments and how to keep the students and myself safe from harm.

if you can get the anhydrous powder then 3% can be made by dissolving 3g made up to 100ml.
if you buy it as say a 30% solution then you would dilute it
10ml of the solution made up to 100ml to make a 3%. to keep it 'pure' use distilled water.

I have been given some special eardrops to use one on Friday and one on Saturday night to go to bed only, its marked on the bottle Bicarbonate of Soda. So I said to the pharmacist 'Why cant I mix up some myself if thats all it is ?' he nearly exploded and said 'No.'
It works well for keeping my ear passages clear of wax and my hearing is much better for it.
Still dont understand.

because you may get the concentrations wrong and that would inflame the delicate ear canal and ear drum Diane.

Seaburn would be right Diane, prolonged skin contact at too high a solution would burn & leave you open to infection. Pure HP is actually odourless Hywel, I know the smell you mean (I used to be a punk in the Seventies 😅) but it must be something else that makes the whiff

I'm obviously trying to read as much as I can on HP so I see some random stuff occasionaly...
Haven't got the link but I read an absolute horror story about a guy that used H2O2 as an anal douche. Never, ever put it inside yourself!!!!! Even in tiny dilutions it's still corrosive over time!!!!
Poor man needed weeks of hospital care, antibiotics to stop him getting blood poisoning through his scorched bowel & stands a chance, in the long term, of having increased his risk of bowel cancer a lot!
As Seaburngirl has pointed out, it's not about the chemical make up, It's about the chemical reaction

can I just remind you that if you take 20ml of peroxide you need to add 180ml of water to make 200ml of 1%. if you add 200ml then you have a less than 1%. its down to proportions.

if it is a starting strength of 12% then to make a 3% solution then 25ml added to 75ml of water will give you 100ml of 3% solution.

This has addled my brain. So much easier to just buy 3% from the chemist shop.

Sorry Seaburn, I'll change that. I meant that I topped it up to 200ml total. Too many late nights...
Not saying you shouldn't do it your way Thorney. Just that I wanted to experiment with HP & record my progress. If I can find effective lowest dilutions then I can do it for less money.

My sister used HP to bleach her hair. She thought she was Marilyn Monroe incarnate. lol! Wow, imagine the damage it can do internally.

That's ok Darren. it is a concept that many students fail to grasp and every year they get a question on it!
even those who you see doing it correctly often write it down incorrectly. it used to drive me mad. mind you not as much as powers of ten to the minus....... they would insist on measuring in cm and then forget they were a decimal place out grrr. I banned them using cm it had to be always measured in microns/mm/m. :o)

I was truly terrible at chemistry in school Seaburn!

Just found your page Darren, and I gave up growing lupins because of aphids. I may try again this year and use your method.