Baking soil to kill fungus gnat larvae

[Fuego012]

This may be a dumb a question…
Is it okay to sterilize roots organics soil ? I’m trying to make sure that I don’t have any fungus gnats or any other types of pest larvae in my soil before I transplant my seedlings, but I’m thinking baking the soil will kill all the microbial life in it . Bake ? Or dont bake ?

Fuego

 

[Natep]

This may be a dumb a question…
Is it okay to sterilize roots organics soil ? I’m trying to make sure that I don’t have any fungus gnats or any other types of pest larvae in my soil before I transplant my seedlings, but I’m thinking baking the soil will kill all the microbial life in it . Bake ? Or dont bake ?

Fuego

Yes you can. You are going to kill all the microbes at the same time. I would look at adding beneficial insect and nematodes instead.

 

[LoveGrowingIt]

I found a way to eradicate fungus gnats: baking soda. Sprinkle it lightly on the soil and moisten it enough for it to penetrate about a half inch into the soil. The fungus gnat larvae eat it and die. It needs to be repeated several times up to at least 17 days, which is the life cycle length of the gnats.

This works. I applied baking soda three times on my current grow. The last application was 17 days after the first. I haven't seen a gnat since.

 

[Fuego012]

I found a way to eradicate fungus gnats: baking soda. Sprinkle it lightly on the soil and moisten it enough for it to penetrate about a half inch into the soil. The fungus gnat larvae eat it and die. It needs to be repeated several times up to at least 17 days, which is the life cycle length of the gnats.

This works. I applied baking soda three times on my current grow. The last application was 17 days after the first. I haven't seen a gnat since.

Would that make the soil p.h lean towards alkaline?

 

[Fuego012]

Yes you can. You are going to kill all the microbes at the same time. I would look at adding beneficial insect and nematodes instead.

That’s seem like a way better idea than baking , thank you .

 

[RhastaBlasta]

You not just "can" do so - it is recommended to. Well, if you buy the soil in plastic bags from the reliable store then this can be skipped, I mean if you trust the soil, but if you wanna re-use it or have any doubts regarding it's content then yes, bake it. Maybe even fire-burn it, that will not hardly hurt the content of the soil while killing all the eggs, fungus and other living stuff you don't want to live near your precious plants

 

[hilbert]

So here's the thing. I am running a bit of a hybrid system with about 40-45% of my medium being perlite. The rest is whatever soil happened to be on sale at the store. When I am mixing my soil, i also add 1 red solo cup full of Diatomaceous Earth per gallon of medium.

So when I mix it's 2 buckets of perlite, 3 buckets of soil, then I add about a gallon (volume) of DE and mix it all together.

Wipes out ALL shit that lays larva in the soil and as an added bonus, adds a bit of silica to the mix as it breaks down.

 

[hilbert]

Actually, probably closer to 2 cups of DE per 5 gallons of media now that I think about it.

 

[cannafarmer420]

This may be a dumb a question…
Is it okay to sterilize roots organics soil ? I’m trying to make sure that I don’t have any fungus gnats or any other types of pest larvae in my soil before I transplant my seedlings, but I’m thinking baking the soil will kill all the microbial life in it . Bake ? Or dont bake ?

Fuego

Just open the bag and let it dry out for a week

 

[brachtlikethat]

If you add some stratiolaelaps scimitus they will prey on the gnat larvae, and will survive on the springtails already present once the gnats are gone, and since you are re using soil you should be able to keep the population of stratiolaelaps going without any further intervention. Also good for thrips species that pupate in soil.

 

[LoveGrowingIt]

Would that [baking soda] make the soil p.h lean towards alkaline?

I considered that, and haven't noticed a pH problem. It's certainly not worse than the gnats themselves. My plants are doing well, and that's the best indication of success I know. The gnat larvae eat it, so it could be changed by them digesting it. The gardening advice articles that recommend it haven't mentioned soil pH as being an issue, probably because it's used in relatively small amounts. I used a few tablespoons, at most, with 5-gallon pots of soil. Ultimately, the effect on the pH of the soil most likely depends on the soil. So, with healthy soil, the effect is most likely trivial to negligible.

The bottom line is this: If you have fungus gnats and want to be rid of them, the baking soda method will do it. It does it better than any other method I've tried, and I tried quite a few before I tried baking soda. It can be used with growing plants, and is inexpensive, readily available and effective.

 

[GreenNotYellow]

Yes you can do that, quite a common practice for cleaning the soil but be careful if you are gonna use something like charcoal or something can you may inlaid the soil with excessive elements. You may wanna wash the soil after, however that again can wash away needed elements...just be careful

 

[Zill]

Scrape away the top 1.5-2” of soil. Replace with fresh out of the bag pasteurized pre mixed soil. Done and dusted.

 

[LoveGrowingIt]

Scrape away the top 1.5-2” of soil. Replace with fresh out of the bag pasteurized pre mixed soil. Done and dusted.

That probably would work. The gnats reportedly occupy the upper area of the soil. Can that scraping be done without damaging the roots? Could larvae migrate to the new soil?

A method I've read about that is similar is to put a half inch of sand on top of the soil to keep the gnats from reproducing. Evidently, they can't do it in sand. I didn't try that method because I reuse my soil and don't want sand in it.

 

[Zill]

Hey LG,

scrape away as much as you can. Top dress the fresh soil with diatomaceous earth. Pretty easy to control.

 

[Zill]

Top dress with DE. Don’t mix in.

 

[LoveGrowingIt]

Just open the bag and let it dry out for a week

I understand gnat eggs can remain dormant for months. They can't live in dry soil, though. So, that works if the soil is dry enough for long enough. Apparently, they can survive in moist soil in the bags for months without reproducing. They need to fly to reproduce.

When I read about using baking soda, the articles explained that the gnats' life cycle is 17 days, so treatments that don't kill the eggs, nymphs or larvae must be repeated for at least that long to be effective.

Letting the soil dry while the plants are growing hasn't worked for me. They come back after every watering. I believe it might be because the watering cycle is shorter than the gnats' reproductive cycle, so the soil doesn't dry long enough.

 

[LoveGrowingIt]

Hey LG,

scrape away as much as you can. Top dress the fresh soil with diatomaceous earth. Pretty easy to control.

I don't want to remove soil, but I understand what you're saying. That top layer is where the larvae thrive. It's the best place to kill them. That's why sprinkling baking soda and spraying lightly with water is so effective.

I have tried DE and found it to be ineffective. Topdressing a thick layer should work, but the DE just washes into the soil when watered. DE is also a bit costly and somewhat dangerous to use. Wear a mask.

Top dress with DE. Don’t mix in.

Definitely.

 

[Mikedin]

Ok here’s my method… since I started it, no more bugs… period

I use misquito bits in 2x 5 gallon water jugs

1/4 cup into each one then top off with water, let sit for about a day then drain the water down to about 3” refill and let sit 24 hours, ready for use. Those same misquito bits stay in the jug with the water and I replace them ever 3 months or so, just refill the jug each time it’s down to 3” left

I also do the DE top dress but when I use DE like that I put about an inch of perlite on top of my soil then sprinkle the DE on top of that after I water so it stays dry on top for them to crawl through

 

[Natep]

If you do bake it I would add a pre charged bio char after. That or harvest some imo and make imo2