One of the most common pests for cannabis plants are fungus gnats. Fungus gnats are a common problem for soil cannabis growers.

Fungus Gnats

They are small and only about 2 mm to 5 mm in size. Despite of their size they can be a big nuisance in your soil cannabis grow. Most of the time these bugs are swarming around the soil and lower portion of your marijuana plant.

Fungus gnats can damage roots and reduce soil drainage weakening the cannabis plant and making it more susceptible to damage and infestation. Even the smallest amount of fungus can attract them, and infestation can happen quickly, often before most can notice.


Preventing Fungus Gnats

It is better to prevent a pest than to combat it. These tips will help you prevent fungus gants:

  • Try to keep the soil as dry as possible, only feed with water if necessary.
  • Keep screens on the windows down all the time.
  • Cover up the substrate with vermiculite or some type of mulching so adult females can’t lay their eggs in the top layer of the substrate.


Combat Cannabis Pests: Fungus Gnats

An ideal product is 'Neem flour'. This product is ideal to combat pests in the substrate, whether flies, larvae or any other insect are feeding upon the roots. It has been shown to be very effective at clearing fungus gnats and other pests that might be lingering.

Certain bacteria can be introduced to the soil in order to destroy invading fungus gnats. Be careful this can also harm your cannabis plant.


The most import thing is that you don't overwater your plants!