For to many years gardeners have dealt with fungus gnats being a “normal” part of growing in organic soils. This couldn't be further from the truth. Fungus gnats do not have to exist in your garden at all. I haven't seen a single gnat in my garden in many years. The biggest key to this is using Gnatrol WDG BTI Pesticide. The active ingredient in Gnatrol is Bacillus Thuringiensis. This is a natural larvacide that will attack the fungus gnat larvae. It is safe to use around humans, and pets, and actually smells sweet because of the carrier the bacteria is on.
To better understand how to deal with fungus gnats, we need to learn a little more about their life cycle. The fungus gnat life cycle is a four stage process. Firstly the egg, then larvae, then pupae, then finally adult fungus gnats. The tiny eggs and pupae occur in damp organic media (your potting soil) where females will lay their eggs and the larvae will feed. In the right temperatures, the eggs will hatch in roughly 3 days. This “rough” temperature is right in line with what temperature your indoor plants like too. Isn't that convenient? :) From here it takes about another 2 weeks to turn into an adult fungus gnat. With the right temperatures you will develop new generations of fungus gnat populations every 17 days. Let that sink in. If you don't do anything, within a couple of months your garden could be completely taken over.
Fungus gnats in low amounts can be a nuisance, in larger populations, they can bring in disease, and possibly kill your plants. I have personally experienced dead plants from nothing other than fungus gnats. The plants didn't completely die, but they were so screwed up that they were not worth saving. So it only made sense to kill the plants and dispose of the soil and pots.
This is where Gnatrol comes into play. The Gnatrol will kill the larvae stage, which to be fare is the longest stage of the cycle, other than being a pesky adult that can regenerate every 17 days. What I have noticed over the years is that the suggested use rate in an indoor garden is always a little to low for complete control. I personally use 1 tablespoon per gallon of water once per week. I like to apply this the same day every week so that the interval between uses stays the same.
If you have a full blown infestation already, then you want to use Gnatrol 3 to 4 times 3 days apart, and then switch to the once per week schedule. Use it at the same 1 tablespoon per gallon of water rate. Besides using Gnatrol weekly, you want to keep your grow room or tent clean. (follow this guide on how to naturally clean your grow room) Keeping the floor and walls clean will leave only your pots or beds as a breeding ground for the gnats. This won't be an issue since you are now nuking the soil with Gnatrol.
Using the method I have described will give you good results, but for the best long term control of fungus gnats, using a multi-pronged approach is best. Here's what I do to get zero gnats in my garden.
- 1- tablespoon of Gnatrol per gallon of water soil drenched once per week.
- Apply Nematodes to the soil once every cycle or roughly every 3 months(Read this to learn how to properly use nematodes)
- Keep a healthy population of Rove Beetles in the soil (Learn how to grow your own rove beetles here)
- Keep a healthy population of Hypoaspis Miles Predatory mites in the soil
- Use fabric containers to pot your plants
If you use all of the above, not only will you not have fungus gnats, you will also be protected from root aphids. One of the best side benefits of fabric containers is the mechanical barrier they provide, Pests simply can't get through them, and it only leaves the soil surface as a possible place of intrusion. With all of the listed defenses I use, the soil surface is so well protected that a pest can't make it through alive. All of this is so low effort that it leaves more time for you to focus on your garden, and less time worrying about pest infestations.
Adding Gnatrol to your garden is a no-brainer for most. You are already watering, so the little bit of extra time it takes for you to mix it in is obviously worth it. When growing valuable crops, don't leave any chance for pests to destroy any or all of your garden. Follow this simple guide to protect yourself and your garden now.