“Welcome back my friends to the show that never ends, we’re so glad you could attend, step inside step inside” (ELP).

I GET A TON OF QUESTIONS ALL THE TIME, and when I see patterns emerging regarding particular misunderstandings, on the rise, so to speak, I do one of these articles where I answer a question and cover that landscape, broadly, with all of my decades of experience growing cannabis. A lot of peeps who are first time converts to going to organically growing/all-natural, get it all set up and then freak out because life is “happening” LoL. Trust me when I say, that is highly amusing to me. Fungus Gnats are one of those living things, that when growing in soil, will happen from time to time. So, you just need to understand a few things about Fungus Gnats, and a living soil mix.

If you’re doing things like composting and making your own soil mix, get ready for some life to be happening, and things like soil mites (totally harmless and beneficial to the plants) or fungus gnats will (should) show up, and some people just freak out; don’t freak out, read on my friends. Today we have a letter from ‘Learning Curve’ as an example, and I have gotten a lot of mail lately where growers new to organic growing, or TLO (True Living Organics 2nd Edition) all-natural style, are like, under the impression that every “bug” is after your plants. Not true; in fact, hardly ever true. Let me tell you all about the good, the bad, and the ugly when it comes to fungus gnats, from bogus (bad) decisions how to deal with them, to various myths, to good management tactics.


“Hey Rev! My first grow with TLO and my first grow ever that is *hopefully* going to completion. One plant now (others were male and composted). Four weeks into flower and have fungus gnats. Think they have stunted growth. Tried drying soil top (removed most of bark mulch and left it for a couple days with an additional small fan), then replaced with fresh bark mulch. Helped quite a bit. Left the added fan in place. Have seen only three in last five days or so. Got Mosquito Bits (variation of Mosquito Dunks) but just don’t know… These ok to use? Really want to do this TLO! Thanks for your SKUNK write-up on Fish fertilizer; saw it today.

Learning Curve”


Rev’s Answer:

I.Make sure you don’t have Root Aphids, and aren’t actually seeing the flying version of these root parasites, rather than fungus gnats. They resemble fungus gnats bigtime; so, this is your first thing to discern before moving forward.

II.I should mention here that if you are a soilless, and/or hydro grower using synthetic fertilizers, and you get a fungus gnat infestation, this can and will do harm to your roots. There is no dead/decomposing organic matter present for the larva to consume, so they are starving, and they adapt to eat living root hairs. So, this is actually a big concern in this case.

III.Alright my green friends, several people have told me they have dealt with gnats successfully by putting a couple/few inches of gravel or sand on top of their soil in growing pots. Please don’t do this in a living soil mix. This will only compact the soil in your containers making less air available, which translates into less microlife; also increases the risk of anaerobic (bad) microlife getting a foothold and radically dropping your pH.

IV.Having a direct fan aimed at your plant that on constantly is NOT A GOOD IDEA and will hyper-dehydrate them. But, good watering habits are essential and overwatering will certainly favor booming fungus gnat infestations along with reducing air available to the soil life. V.Many of you have expressed concerns to me regarding the diseases that fungus gnats potentially can carry. I cannot say this more plainly: if your grow rooms are disease free, and the fungus gnats were born in your grow room, then the fungus gnats are disease free. You savvy?

VI.Fungus gnat larva in the soil are like mass-transit systems for bacteria. Bacteria don’t really travel, they colonize. But, with fast moving hosts like the fungus gnat larva they can “catch a ride” with, they are able to expand their turf in the container, which is a very good thing. Cannabis favors a bacterially dominant soil.

VII.Fungus gnat larva are awesome at processing organic matter in your soil mix much like soil mites and others will do, all contributing to the happiness of your plants in a living soil mix.

VIII.A couple times a year maybe I get a few too many gnats buzzing around and I have a really simple methodology for handling them and knocking them down a big notch in numbers. I use BT and fly strips. Now, in the photo is the BT product I have used successfully at least 3 times myself and many more times for local friend’s gardens. However, it should be noted here that I read study by a college in California that concluded this strain of BT (in the photo) was ineffective against fungus gnats. All I have to say to that is, I disagree from first hand experience. But, the strain of BT in mosquito dunks they concluded did in fact attack fungus gnat larva. BT is a harmless form of bacteria, so no worries. So, you may want to use the BT that hunts mosquito larva.

IX.A few gnats are no big deal, and a good sign; in my opinion—life is good. I said it before and I’ll say it again, don’t freak out amigos. Now, if you have brought some kind of soil addition like compost or mulch that has brought the gnats, your concerns regarding the disease carrying aspect of these critters is a tad increased, but still low.


Rule of thumb per Rev: if you notice bugs, and they are not attracted to your living plant, but rather just running amok in the soil. Then assume they are your friends and they are helping you towards your goal of a stunning cannabis harvest.</br>


The BT product I have used successfully in the past

Harmless flypaper – do not fear the brand in this case

Here’s how I do the gnat treatment with the BT product shown in the photo. I mix about 1 tablespoon of the powder, per gallon of chlorine free water, and then I go around to all my plants pouring about 10 oz. on larger 2-gallon containers and about 2 oz. on smaller 3͟ containers. Boom… That’s it man, in about 8-10 days no more gnats for a while, then, just back to a few like normal. The sticky flypaper is just hung up where the flying buggers are at, and this will really knock them down fast while the BT does its work.

You can easily tell when your plants are very happy

Happy gardens to you all, tis the season to be jolly so smoke one and remember not to freak out about life if you are growing in living soil, and, in my opinion, soil that isn’t living isn’t soil, ya follow? Bye for now and I’ll see you again soon in the next installment—cheers.