Reusing soil

What are the do's and don'ts regarding soil reuse? I have 2 large totes of soil, I left them on my balcony for the beginning of winter to freeze out any fungus gnats I had from my last grow. The end of the grow I had 0 visible flying pests, I figured I'd keep the soil outside to freeze and I would bring it back in to defrost (the soil is fairly frozen) and reuse. Is this safe for my new plants to live in?

If you’re doing rols then reuse the soil, if you’re just using synthetic mutes, I would suggest not reusing soil. You are increasing the chance of all kinds of issues including bugs and mold

kmog33 said:

If you’re doing rols then reuse the soil, if you’re just using synthetic mutes, I would suggest not reusing soil. You are increasing the chance of all kinds of issues including bugs and mold

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I'm using rootfarm nutes, I also live on the 9th floor of a large apartment so I'm hoping bugs won't be an issue. I mixed the soil up really good after defrosting and the soil seemed to be just fine. Anyway they are transplanted into the large totes now, fingers crossed I didn't just condemn my girls to death

Macintyre22 said:

I'm using rootfarm nutes, I also live on the 9th floor of a large apartment so I'm hoping bugs won't be an issue. I mixed the soil up really good after defrosting and the soil seemed to be just fine. Anyway they are transplanted into the large totes now, fingers crossed I didn't just condemn my girls to death

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You always have some chance of issues with soil even when it’s brand new, it sort of holds into spores and shit you don’t want. You could probably pasteurize it if you wanted it clean. But then it would be more like coco than soil. There‘a a good chance you won’t have any issue, but in general, using new media or sterilizing is usually good, outside of reused organic setups. Granted I don’t know everything and people do good in weird environments so just pay attention to your plants.

You can reuse coco with synthetic nutes a few times (make sure to flush old salts and reset the EC with fresh nutes by checking your runout), but peat seems to break down after a grow cycle. It is usually better to start fresh. Most of my experience is with organic nutes. So, the media might break down faster than with salt based, but everytime I try to reuse my media I have trouble. Aside from the breakdown of the media, you also have all of the root mass left over in the soil. Im not saying it is impossible, but It would be very difficult to separate all of the old roots from the media.

I tried to reuse media many times, but was not successful. Intuitively, you would think you could reuse your soil. Nobody replaces the earth every year, but for whatever reason container gardening is different. The longer it is kept around used media seems to behave more and more like humus.

If you want a consistent growing experience start fresh each time.

Microbes for your roots are a good option to deal with old roots. You do need to make sure the soil is extremely wel flushed because if there is salt build up it will really fuck woth your nutrient uptake

I flushed my plants for around a month before my last harvest, and I removed most of the roots, there are some little hair-like roots still visible but I was told they would just turn into compost. After I removed the roots I applied a LOT of diatomaceous earth and mixed it in into the soil to kill off any potential surviving eggs (fungus gnats) prior to freezing the soil. Here's hoping all goes well lol

kmog33 said:

Microbes for your roots are a good option to deal with old roots. You do need to make sure the soil is extremely wel flushed because if there is salt build up it will really fuck woth your nutrient uptake

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Getting rid of roots is super easy. Let the soil completely dry in the pot it was planted in, then grab the remaining stem and pull the whole root ball and soil up together. Get a big tub and just smack the rootball against the side of the tub and all the soil will fall out and when your done you will have a root ball in your hand and soil in the tub.

I think why take the risk tbh. I always try to minimise risk in every way possible.

There are people that reuse their soil and have awesome grows. Some say it just keeps getting better. You might want to head over to the Organics section and browse through the threads. Good luck.

The other possible problem you might come up against is the remaining nutrient profile of the soil. Especially if you flushed. I would grab some dry amendments and mix them in. Otherwise you'll likely get some deficiencies, and maybe excess of some nutrients.
Freezing the soil probably won't kill the eggs of the fungus gnats. They overwinter in the soil in nature don't they? You should only see them if the medium is too damp anyway. Putting a layer of horticultural sand on top of your soil would help keep the adults from reaching the damp soil to lay eggs.

I've had problems with gnats and with scale growing other types of plants. They're so damaging to the plant that they always kill it off eventually and spread themselves around. (Less of an issue with a plant you'll kill at harvest anyway, still an issue if you have other vulnerable plants nearby).

Thus, this is partly my personal paranoia but if the soil got infested, I'd toss it. I'm not sure I'd trust any method to kill those eggs off short of an autoclave.

I always reuse my soil hell I just moved and brought my soil with me in 55 gal barrels and got soil here to start a new batch. No till will most definitely get better with age. I used the batch I brought with me for 3 to 5 yrs. for my no till soil I simply cut the plant off and plant the new next to the stump lol.

Also check in to cover crops and I even add a few worms if you are doing the whole reuse deal. It helps keep the soil balanced and from compacting too much.

The problems with reusing soil arise when users get caught in the relatively unpredictable middle ground, between chemical feeding, and proper soil building.

I reuse successfully with roots organics soils as a base, with looooong periods of "cooking" in between,only after adding fresh EWC and dry organic amendments.

Macintyre22 said:

What are the do's and don'ts regarding soil reuse? I have 2 large totes of soil, I left them on my balcony for the beginning of winter to freeze out any fungus gnats I had from my last grow. The end of the grow I had 0 visible flying pests, I figured I'd keep the soil outside to freeze and I would bring it back in to defrost (the soil is fairly frozen) and reuse. Is this safe for my new plants to live in?

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fungus gnats live outdoors...freezing doesn't do shit to their eggs, they just wake up and hatch in the spring...
you can reuse soil many times, practically forever, as long as you keep amending it.