Pest Control, Plant Care, Tips & Advice

I hate Fungus Gnats too! There must be a solution.

There are probably 2 pests that I hate even more than the rest. Mealy Bug and Fungus Gnats. Aaargggh!

If you have little flying bug around your plant pots or plant tray that look a little like small mosquitoes, chances are you have a healthy Fungus Gnat infestation.

If you have a Fungus Gnat population taking up residence in your potted plants, there are many ways to fight them, but depending how bad the infestation is, 2 techniques seem to give you least amount of work. Creating the right soil barriers to deter breeding, and then actually getting rid of them by using something like a sticky Trap.

Why is it not good having Fungus Gnats in your plants? Well, apart from the obvious nuisance they are as they fly around getting on your nerves, they actually can damage tender roots and subterranean stems, as they also feed on organic matter in your mix. Even though they only live for about 1 week once hatched, they can each lay several hundred eggs and can effect the health of your beloved plant. They can also spread pythium, which is a group of plant pathogens that can cause seedlings to rot.

Adult Fungus Gnat
Adult Fungus Gnat

The first thing to do is make sure your conditions make it harder for Fungus Gnats to live comfortably in your plants.

    1. When buying your plant, have a check to see if there are any gnats flying up when you disturb the top of the soil, and look for small, clear larvae near the surface. DO NOT BUY EFFECTED PLANTS.
    2. Having potting media that is constantly damp provides the perfect breeding environment, so if you can, having bigger particles in the mix, even if it is just at the surface, can make it harder for them to produce larvae. Some course sand, perlite, pebbles, etc. across the surface of your mix can definitely help.
    3. Do not overwater – especially in the cooler months. Having the mix dry out at the surface will reduce the larvae population. Consider whether you can water your plant via ‘bottom-up’ techniques.
    4. Good air circulation around your plants can definitely help.

The second important technique of controlling Fungus Gnats is to place a Green or Yellow Sticky Trap in your pot close to (above) the surface of the mix.

My understanding is that Fungus Gnats see 2 colours more vividly than other colours; Green and Yellow. Maybe they look for the green because they know plants provide them with the conditions they need to make a happy home. Click here to view our range of Sticky Traps for purchase;

Other treatment and prevention options are…

A) Whilst taking a bit more effort, the release of beneficial live worms/organisms into your mix that predate on the larvae of Fungus Gnats – be careful not to treat the soil with harmful sprays etc if you are doing this method.

B) The use of sprays or treatments may also have it’s place, but can be generally more negatively impacting on the environment. You can research these yourself.

C) A treatment of hydrogen peroxide can be effective, use a mixture of one part 3% hydrogen peroxide mixed with four parts water, then applied to the soil. This should not be harmful to the plant, but check it out further before trying. 

Healthy gardens to you all!