Yep, big fan here of hydrogen peroxide for my plants too. I love that cleaning and health companies recognise the benefits of hydrogen peroxide for plants too, so we now get our own formulas actually made for houseplants.
Like Forsana's Plant Care Plus 3% or the newer OXY 3% from GT. Although both are the 3% strength recommended for plants, they are different formulas.
Forsana adds extra beneficial goodies versus GT which use pure 3% hydrogen peroxide. Both are great options for a long list of problem-solving for our houseplants.
No matter what brand your hydrogen peroxide is, here's what you need to know BEFORE you mix it with anything other than water...
If used for control of soil pests like fungus gnats, and soil diseases like root rot, you may only be using hydrogen peroxide as a fix instead of a preventative.
Problem gone, hydrogen peroxide goes back into the plant cupboard. Job done.
But if you want to use it on the regular for the root benefits - and to prevent soil pests and diseases from even becoming a problem in the first place - it makes sense to want to save time and avoid over-watering by MIXING hydrogen peroxide in the SAME water with your fertiliser or other nutrients, rather than watering it in separately.
Can you mix hydrogen peroxide with fertiliser in the same water?
Yes, maybe and no. It depends on two things:
What's in your fertiliser or other nutrients,
AND the amount of hydrogen peroxide you're adding.
This will help you work out if it's a yes, maybe or no for your plants...
What's going on is actually hydrogen peroxide doing what it does so well. If your fertiliser is fully synthetic, no organic nutrients in the mix, and you're using one of the lower dilution rates of hydrogen peroxide (like for algae control at 15mls hydrogen peroxide per 1 litre of water), a reaction is unlikely and the answer is probably YES.
But again, it still depends on what's in your nutrients. More about that up next.
But at higher dilution rates, such as fungus gnat control (up around 150ml hydrogen peroxide per 1 litre water), the answer is an easy NO.
At higher strengths, hydrogen peroxide is more likely to react with nutrients. Use it by itself, just with plain water, at those higher dilution rates.
Back to the other half of what matters, what's in your fertiliser or other nutrients...
A lot of the higher quality plant fertilisers are fully synthetic, but some are a blend, such as seaweed and NPK. Others protect some minerals with an organic treatment, called chelation.
Iron is a common one, along with other metal nutrients, as chelation helps prevent metal minerals getting locked in the soil vs the roots being able to absorb them.
If you look up your fertiliser info and it says any of the minerals are chelated, that counts as an organic treatment.
Even then, a majority synthetic fertiliser with some chelated minerals is still unlikely to react at the low hydrogen peroxide dilution rates,
But if your nutrient or fertiliser is big on organics, like ones with seaweed, humic or fulvic acids, or has added plant hormones like auxins, the easy answer is NO for those.
It's best to avoid mixing fully or mainly organic nutrients with hydrogen peroxide in the same water.
As for what happens, it's not likely to cause major issues, but does make mixing them a bit pointless if they react.
Plus, it's impossible to test every brand and combination of fertiliser and other nutrients with every dilution rate of hydrogen peroxide.
So no matter what, this is all OFF LABEL use. That means it's at your own risk.
One thing that can happen is the hydrogen peroxide starts working before you've even get it where it needs to be. Hydrogen peroxide is quick acting, rapidly breaking down into oxygen and water, so you always want to mix it fresh, straight before watering it in to roots or spraying it on foliage, so it gets where it needs to be ASAP.
Hydrogen peroxide can also break down those organic nutrients, before the plant's roots get a look in, wasting your money, and meaning your plant might miss out.
But, if you do decide to mix it, make up your nutrient solution first, stir, then always add the hydrogen peroxide to the nutrient solution LAST, immediately before watering or spraying. Don't let it sit.
Looking for hydrogen peroxide safe for plant use?
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