Sterilizing soil using Hydrogen Peroxide

fredman

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I'm thinking sterilizing the medium to try and strike azalea cuttings. Anyone used that before?
I have 3% and 30% HP on hand. What percentage..or dilution will be effective?
Thanks.
 

Lorax7

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I’m not so sure you really can sterilize soil with hydrogen peroxide. Hydroxy radical formation occurs so rapidly via the Fenton reaction in the presence of an iron catalyst that I doubt that unreacted hydrogen peroxide makes it through to the bottom of the soil column (assuming that you’re pouring it on top).
 

penumbra

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I’m not so sure you really can sterilize soil with hydrogen peroxide. Hydroxy radical formation occurs so rapidly via the Fenton reaction in the presence of an iron catalyst that I doubt that unreacted hydrogen peroxide makes it through to the bottom of the soil column (assuming that you’re pouring it on top).
Rather than try to sterilize soil, why don't you just start with sterile media to begin with?
I agree with both of these statements but peroxide does have benefits and at a low rate can do no harm. It does rapidly destroy fungus spores and has long been used in mushroom culture to destroy spores of competing mushroom strains. It also gives a little shot of extra oxygen. I almost always soak cuttings in a weak peroxide solution overnight before sticking them in a sterile medium. I also use it in jars that are used to root cuttings in water. Most recently I had very serious fungus gnat problem on one particular ficus. I soaked the soil with a mild peroxide solution and finally after trying everything else, I am gnat free. Fungus gnats are not usually a problem for me but this one Burt Davii was not responding to other measures. Now I haven't seen a fungus gnat anywhere near it in about 90 days.
I think peroxide is much under appreciated and under valued. I also use it in both fresh and salt water aquariums every once in awhile. Kills monocelluler algae quickly as well.
 

fredman

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I’m not so sure you really can sterilize soil with hydrogen peroxide. Hydroxy radical formation occurs so rapidly via the Fenton reaction in the presence of an iron catalyst that I doubt that unreacted hydrogen peroxide makes it through to the bottom of the soil column (assuming that you’re pouring it on top).
I can dunk the whole lot for a while. That'll soak everything properly.
Rather than try to sterilize soil, why don't you just start with sterile media to begin with?
Hey Bossman. Good to see you again ;)
You're blowing my bubble you know. I've got soil..and HP and i'm ready to tinker...plus i'm stingy. :p
 

Arnold

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I use bleach to sterilize inorganic soil like lava rock and pumice and works well, I dont use it in organic soils tho
 

Deep Sea Diver

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Gosh. I concur with @Bonsai Nut it would be best to just pay the Vig and get sterile soil from the gitgo.

I honestly don’t think it’s practical to entirely sterilize a cutting media with H2O2. The highest concentration H2O2 I’ve heard used (once again to eradicate fungus gnats larva) was 1 part 3% to 4 parts of water.

I reuse inorganic bonsai media by water washing, draining, then heating in an oven to 400F for an hour, cooling, then shifting for size…. adding akadama as needed. Works really good, yet it’s time consuming.

I don’t recommend doing this procedure with a seeding/cutting mix though, unless you want the local Fire squad to visit!

If you must go for it…. I’d say your best bet would be to boil your mix in a big cooking pot for 15+ minutes, cool and drain, squeeze as needed and strike your cuttings. This ought to work well for cutting purposes . Warning: it’s best to get a kitchen pass before attempting this procedure!

Let us know what you decide to do. I’m interested in hearing what you decide. 😎

Cheers
DSD sends
 

penumbra

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The highest concentration H2O2 I’ve heard used (once again to eradicate fungus gnats larva) was 1 part 3% to 4 parts of water.
I use one part H2O2 to one to two parts water. As a spray I use it more diluted on seedlings.
I reuse inorganic bonsai media by water washing, draining, then heating in an oven to 400F for an hour, cooling,
This is the most practical way to sterilize and be certain of it.
 

fredman

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Gosh. I concur with @Bonsai Nut it would be best to just pay the Vig and get sterile soil from the gitgo.

I honestly don’t think it’s practical to entirely sterilize a cutting media with H2O2. The highest concentration H2O2 I’ve heard used (once again to eradicate fungus gnats larva) was 1 part 3% to 4 parts of water.

I reuse inorganic bonsai media by water washing, draining, then heating in an oven to 400F for an hour, cooling, then shifting for size…. adding akadama as needed. Works really good, yet it’s time consuming.

I don’t recommend doing this procedure with a seeding/cutting mix though, unless you want the local Fire squad to visit!

If you must go for it…. I’d say your best bet would be to boil your mix in a big cooking pot for 15+ minutes, cool and drain, squeeze as needed and strike your cuttings. This ought to work well for cutting purposes . Warning: it’s best to get a kitchen pass before attempting this procedure!

Let us know what you decide to do. I’m interested in hearing what you decide. 😎

Cheers
DSD sends
Thanks mate. This makes a lot of sense to me. I'll stuff the soil into the wife's old stocking and boil it for a while.
I only have a few cuttings from one tree to do, so I don't need much.
 

Shibui

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400F is pretty hot. That's 200C! I guess that is real sterilize temps but complete sterilization is not really needed for most propagation purposes.
I have on old microwave in the shed that is mostly used to sanitize propagation mix. Boiling will get the temp up around 212F -100C. The microwave will do that no problem and there's no mess with excess water.
 

Wires_Guy_wires

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True sterilisation can be achieved with a pressure cooker quite easily. 40 minutes on pressurized heat is commonly used for mushroom media like rye. Water under pressure reaches about 120-122°C and the pressure will burst all bacterial and fungal spores.
But the fun part is that as soon as you expose it to air, it'll be non-sterile again.

Put the stuff in mason jars, don't screw the lid on but instead lay it on top. After cooling, open the cooker and twist the lids so they close. You now have a stash of sterilized medium.

When I still did tissue culture at home, I disinfected my micro-cuttings with 70% ethanol for 2 minutes, then a 20% bleach solution for 3 minutes, then a triple sterilized water rinse for 1 minute each.
 

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But the fun part is that as soon as you expose it to air, it'll be non-sterile again.
Exactly what I was wondering. Where do you then place the cuttings & container..?
To be honest, I have never given sterilization much thought :(
 

Lorax7

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To be honest, I have never given sterilization much thought :(
Same here. I recycle old bonsai substrate by sticking the container full of used substrate in the garage, letting it dry out over the course of a season, and then sifting and reusing it. The idea of sterilizing it never occurred to me.
 

penumbra

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Same here. I recycle old bonsai substrate by sticking the container full of used substrate in the garage, letting it dry out over the course of a season, and then sifting and reusing it. The idea of sterilizing it never occurred to me.
To be fair, the OP was talking about azalea cuttings in a sterile rooting mix, not bonsai in bonsai mix.
Two Very different animals.
 

Lorax7

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To be fair, the OP was talking about azalea cuttings in a sterile rooting mix, not bonsai in bonsai mix.
Two Very different animals.
I've never sterilized substrate for cuttings either. I just take the cutting and stick it in bonsai soil and if it survives it survives. That said, I don't have a very high rate of success with cuttings because I'm not trying hard at all to create ideal conditions. It's more just something that I do when I happen to be pruning a tree, that I'll stick some of the cuttings in soil because, why not? Sometimes, I'm not even preparing a separate container. I just stick the cutting right in the pot with the bonsai that I'm pruning. If the cutting survives and grows, I'll separate it out and put it in its own pot the next time I repot the bonsai.
 

Deep Sea Diver

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Cool idea tossing the media in the pressure cooker! I’ll run that by the Fleet Admiral for approval, yet somehow I doubt she’ll let me use her Instant Pot for this experiment. But a fun and effective idea @Wires_Guy_wires !

Over here I do trials with a lot of azalea and other tree cuttings. This last summer‘s efforts included right at 450 cuttings (5 to a pot) from 70 different azalea cultivars in addition to other cuttings of maples, English hawthorn etc. Organic and inorganic media is used depending on the cultivar and test.

From my limited experience, if one is going to be successful with a crop of azalea cuttings, it doesn’t take a whole lot of equipment… heating mats, trays and covers of some sort, and maybe a couple lights, yet of all the variety of material that can be used, I find a stable, clean source of media is important for azalea cuttings .….

While I won’t comment on others methods of striking cuttings and successfully growing these out over the succeeding year, I can say that that is my experience. Also I personally wouldn’t use 100 percent perlite myself for azaleas, but would be very interested to know the the actual results of using this media.

So @fredman ‘s effort to ensure his media is ’sterile’ imo is valid…. and interesting to me. Especially interesting would be knowing the type of media and the year long results.

As far as sterilizing media for older trees goes, I don’t have a large depth of knowledge to draw from. I originally did this as as a trial as I couldn’t get media materials quickly and was short of cash anyways... and continue this process still. I received my information about the need for ‘clean’ media from a large trial, years ago, to reuse media that wasn’t sterilized at the museum where I volunteer. From their experience the results where not pretty…. and were never attempted again.

The temperature used was my choice. My Mom’s baseline standard for cooking most anything in the oven, back in the day, was 350 for 40 mins. So I non scientifically figured I’d go a bit higher…. the length had to do with getting the media dry. So lowering the temperature is entirely possible, but may take more time.

Cheers,
DSD sends

btw: I haven’t tried to sterilize the Kanuma mix I use yet. I have finally gotten enough to try heating a batch. The results of this trial will be very interesting, especially economically considering the recent price increases.
 

Wires_Guy_wires

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Just FYI: I'm against the use of sterile media if we're not doing it entirely aseptic. I use sterile media for plants that come from a sterile environment and go back into a sterile environment with 20um air filters. Sterile media are perfect feeding grounds for everything, also for the stuff that eats our plants. Without natural competiton, it's first come first served.
If you want to get rid of animals and insects, store it dry for a month. Wet it, spread, let dry again. Everything that hatches will die before it can reproduce. One or two cycles is enough.

Peat, especially the acidic black bog stuff, is great for cuttings. Good for preservation of a lot of things, including ancient boats, mammoths and even humans.

Pressure cookers get a beating if conifer wood ever ends up in there. I remember treating some mixed woods, including pine. It ruined the cooker entirely. Also.. The stuff in the steam is a highly phenolic mixture that - when dried - can be extremely explosive. Hardwoods and other non resinous woods are fine though!
I'm also not entirely sure how soil particle pores hold up under pressure.

Best to use a pressure cooker for quick-made pulled chicken: bagged with spices, sauce and all, 10-20 minutes on full steam and 15 minutes on the grill should equal 3 hours in the oven. Stab the chicken before pressure cooking and it'll be infused with flavor.
 

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