sterilizing soil

i.am.what.i.am

Well-Known Member
am transplanting today, but just noticed gnats in the soil bags i was gonna use. how do you guys sterilize your soil in the oven? how long and at what temps do you heat it for? thanks!
 

pmumbry

Active Member
get some diatomaceous earth and mix in 2 cups per cubic foot into your soil thoroughly, transplant the plants, then lightly sprinkle more diatomaceous earth all over the surface of the soil in the pot. Those gnats will be toast. It is organic, and it won;t kill off your beneficial microbes like baking the soil will.
 

Nullis

Moderator
Uh uh no no, never have I baked any soil in the oven. Soil is supposed to alive, seriously.

The problem with DE on top of\in your soil is that it really needs to be dry in order to work. It does work well in crevices, worked into carpets, where ever else you see adults flying around.

You should have yellow sticky traps, I like the Safer stakes but you should use the hanging traps as well. Also look into Bacillus thuringiensis israeli, or go get some Mosquito Dunks, soak them in water over night and use that for fertigation. This will kill the larvae, which is a crucial stage to kill.

Please use the search function, you can even search just my posts for "fungus gnats" because I have previously written up\posted lots more recommendations that I can put here ATM.
 

SpliffAndMyLady

Well-Known Member
[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Cook it at 170-180 degree's for 20 mins and then let it cool thoroughly.[/FONT]
 

growone

Well-Known Member
there's sterilize, and that means kill 'em all
then there's pasteurizing, lower temps, and good things live, baddies go away
someone mentioned 170/180. those are good temps, i personally go to 200, but it's also a question of size of the soil container, bigger will take longer to heat up
 

PurpleBuz

Well-Known Member
am transplanting today, but just noticed gnats in the soil bags i was gonna use. how do you guys sterilize your soil in the oven? how long and at what temps do you heat it for? thanks!
Preheat oven to 200F
Load soil into trays, moisten soil if its dry water is essential, cover tray so the water can "steam up" inside the tray.
Put the trays in and Turn oven down to 180.
After 15 minutes turn oven to 160 and leave it there for at least an hour. You can leave it like that for hours.

This will pasteurize and not sterilize. If you want active microbes then water them in afterwards so they can colonize.
Normally I used pasteurized soil only when I am doing cuttings. to make sure there isn't any pythium or other real nasties. But this should work fine for gnats.
 

Fazer1rlg

Active Member
Don't Cook the soil! Nullis knows what he is talking about u will kill the microbes and beneficial bacteria in your soil. Use some organic pyrethrim that should get rid of the gnats use it for 2 weeks once a week. That's the whole point of soil itis ALIVE treat it that way you will make your house stink when u cook that shit u will wont like that.
 

bigv1976

Well-Known Member
I cant believe anyone here would reccomend this guy uses soil with bugs in it. You should all be ashamed of yourselves. Dude throw that soil away and get some quality soil.
 

Nullis

Moderator
^Why? There kind of should be bugs in soil. My soil has bugs in it, including Collembola and predator mites. Of course there are some bugs that are pests that if noticed you'd want to avoid at all costs, but over some stupid fungus gnats?

Like I said in my first post, Bti\Gnatrol\Mosquito Dunks will kill the larva and sticky traps will catch the adults. We can't know exactly how severe an issue it is, if at all, or if it was just a few gnat larva in the mix or adults seen flying around.

The OP essentially asked how I would sterilize my soil in the oven if I noticed gnats; my answer was that I wouldn't and a gave a suggestion. Not going to be ashamed for that.
 

growone

Well-Known Member
Nullis has a reasonable point about fungus gnats and overkill, if it's just gnats they can be dealt with in other ways
and fungus gnats show up in the best dirt from time to time, seen complaints across the spectrum
what i like about heat pasteurization is that it takes out all nasties in an very effective way
commercial greenhouses routinely use large autoclaves to keep their soil pest free
 
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