Sterilizing soil.

[natale]

Hello All!

I was just wondering if anyone has ever baked soil in the oven as a means of sterilizing the soil which is ridden with fungus gnats. I realize I could just throw the soil out, sterilize the pots, and start over, but it seems so wasteful, as I have over 100 pounds of soil. I had tried several other methods before, like dish soap, hydrogen peroxide, and other pesticides, but nothing really seemed to work and all of those methods did a number on my plants. So I decided to throw out all of the dying plants, bake the soil at 180-200 degrees F for about 30 minutes, and put the hot soil into airtight containers.

The containers have some condensation on the inside, but for the most part, it seems bug free. Now bacteria free, that's another question. Does anyone know if this method may have worked? Worked well enough that the fungus gnat party is over? Is it possible that I have created more bacteria by putting the hot soil into the air tight containers and allowed them to cool down? Any advice on this is helpful.

It seems that there are much fewer gnats flying around. I have several about 20 other potted plants throughout my apartment that were not showing signs of root rot, the soil was drying out appropriately, etc, so I've kept them as they are and put a layer of sand or cinnamon on the surface of the soil to prevent gnats from invading them. It seems to be working so far. Of course I don't expect to completely eradicate them, but it seems that putting the dirty soil in airtight containers and keeping the healthy plants as they are has cut down the gnats by at least 75%.

I'm just hoping that once I plant new plants using the sterilized soil, I won't have the same problem all over again. Of course, I won't over water and use gigantic pots as I did before, which caused the bacteria in the first place. Also, the awful garbage stench from the bacteria in the gross pots is gone. The sterilized soil just smells like regular soil.

If anyone has any advice, I greatly appreciate it! thanks!

 

[Upsy Daisy]

I use the microwave method and have had no problems


https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/sterilizing-soil.htm

 

[Chuck]

A hundred pounds of soil in an over will take forever won't it? But as far as insects breeding in the soil you can stop that by adding a little spinosad based insecticide to your water and water your plants with the mix. The picture is of my super modern high tec soil sterilization unit.[ATTACH=full

 

[natale]

It did take forever. I basically loaded up 12"x12" containers and did the baking in large batches to fill a container at a time. I still have one batch to go. I'm pretty confident that the soil is free of bacteria now because that awful smell is gone. The soil just smells nice and earthy now. When I replant, I'll be sure to have lots of food and fertilizer for the plants, as some say this method kills off good nutrients. I'll look into spinosad insecticide as well. I don't want these gnats coming back. I had house guests when the gnats were at an all time high and everyone was getting gnats in their food and drinks to the point that we all just had to go outside. it was disgusting. Now there are just a few. I can definitely deal with the current amount of gnats, but still want to take measures to get rid of them.

 

[Chuck]

It did take forever. I basically loaded up 12"x12" containers and did the baking in large batches to fill a container at a time. I still have one batch to go. I'm pretty confident that the soil is free of bacteria now because that awful smell is gone. The soil just smells nice and earthy now. When I replant, I'll be sure to have lots of food and fertilizer for the plants, as some say this method kills off good nutrients. I'll look into spinosad insecticide as well. I don't want these gnats coming back. I had house guests when the gnats were at an all time high and everyone was getting gnats in their food and drinks to the point that we all just had to go outside. it was disgusting. Now there are just a few. I can definitely deal with the current amount of gnats, but still want to take measures to get rid of them.

Soil sterilization does not kill nutrients i.e NPK. What it kills is fungi, bacteria and the soil micro-organisms that are necessary for nutrient uptake. Soil sterilization is used mainly for seed starting as the seed itself has enough nutrients for the plant to grow until its roots take over the nutrient absorbing process at which time the plant should be transplanted into a microbial rich growing medium.

 

[DirtMechanic]

I found success with thymol. it smells, but has been proven to have antifungal, antibacterial and insecticidal properties. Its also a contact killer for a lot of pathogens, nematodes and possibily your bugs but since they have feet I am betting they just won't care for the smell.

 

[natale]

Well it turns out my containers aren't so airtight after all. It doesn't look like bugs are getting in there, but they can. There are still several gnats flying around the kitchen area, but much fewer and they are much smaller. So...I basically have baked soil in two giant flats that have clamp down handles, but there's definitely space for gnats to crawl in and lay eggs , several other bags of soil tied up as airtight as I can make them, and several plants that are growing healthily and don't seem to have bugs hanging around in them.

I just noticed tonight, while cooking dinner, that I couldn't really leave anything I was cooking uncovered, as gnats would start swarming around. Fewer gnats, smaller gnats...I tried the potato slice thing and didn't see any larvae...the yellow glue traps aren't trapping any more gnats, I bought a bug zapper and it goes off constantly...so basically any time I move a plant, pot, soil, kitchen stuff, etc, I hear a bug get zapped, but they're small enough that I don't see them and they're not flying up in my face.

I think I reduced the problem but I don't know if I can full blown eradicate them, since I have other plants that I'm not replanting, trash, recycling, etc...those lil jerks can live in anything. I'm glad to know @Chuck that I didn't kill off any good nutrients. I didn't think so. I think I managed to kill the bacteria, but gnats can still get in the soil and breed if they feel like it. I'm hoping that when I start all my seeds in a week, that soil will still be fungi free.

@DirtMechanic I'll look into thymol. I don't care if it smells. I bet it doesn't smell as bad as bacteria ridden dirt.

 

[DirtMechanic]

Humagro Promax

https://humagro.com/promax

 

[natale]

Oh and @DirtMechanic, the tomato plant I split and brought half inside is completely going droopy on me, meanwhile, the tomato plants outside are just a few months away from making sandwiches. I think I'm just going to move everything outside, in secret spots around the apartment building, once I've got seedlings started and just let it be. Let it be. It's gonna take patience and time. I just need to listen to George Harrison's advice a little more often.

 

[natale]

Humagro Promax

https://humagro.com/promax

Are they for big time commercial stuff? I've just got an apartment garden...a failing one, at that. Although I'm seriously considering setting up a desert greenhouse space or something. Urban gardening is getting annoying.

 

[DirtMechanic]

Its the background sure, but thats true for everything. You can buy thymol or thyme oil and make your own, these guys just premake it in a humic acid mix in a more agronomic product. You will need a carrier oil like canola oil from the kitchen if you diy. It goes a long way.

Or go hydro..

 

[natale]

Its the background sure, but thats true for everything. You can buy thymol or thyme oil and make your own, these guys just premake it in a humic acid mix in a more agronomic product. You will need a carrier oil like canola oil from the kitchen if you diy. It goes a long way.

Or go hydro..

Oh, I make essential oils, so I'd be interested in making my own or giving the a shot. Or buying some thymol.

What do you mean go hydro?

 

[DirtMechanic]

Hydroponics. There are some distinct advantages. And probably a different set of hassles too.

 

[alp]

I microwave mine for germination of fine seeds. Bigger seeds like runner beans, I just use ordinary compost.

 

[natale]

Hydroponics. There are some distinct advantages. And probably a different set of hassles too.

Ok. I mean I thought you meant that. I grow some things that way. It doesn't really work for everything