How to Get Rid of Gnats in Houseplants


Fungus gnats live and breed on fungus that grows on the wet soil of houseplants. Once airborne, these gnats often hover around houseplants or nearby windows. Fungus gnats do not harm houseplants, but they can be annoying to have around the house. Since adult fungus gnats only live a few days, they are easy to get rid of. However, your house infestation likely came in from a larger outdoor population, so there's no guarantee they won't be back.

Step 1

Set yellow sticky traps (available at most garden centers) around your houseplants to trap any swarming adult fungus gnats.

Step 2

Treat your houseplant's soil with a bacterial insecticide like Gnatrol or Knock-out. These products contain a strain of Bacillus thuringiensis, a naturally occurring soil bacteria that will kill any incubating fungus gnat larvae.

Step 3

Spray your houseplant with a pyrethrin or pyrethroid insecticide like Dragnet, Pounce or Torpedo if the infestation is severe. These insecticides will kill adult fungus gnats, eggs and larvae. Follow the manufacturer's instructions for application and frequency rates.

Step 4

Eliminate the fungus gnats' food source. Discourage fungus growth by avoiding high-organic-matter soil or fish-emulsion fertilizers and allowing the soil to dry out between waterings.

Things You'll Need

  • Yellow sticky trap
  • Insecticide


  • Colorado State University: Managing Houseplant Pests
  • Caring for Houseplants: Gnats in Houseplants
  • University of Minnesota: Houseplant Insect Control
Keywords: fungus gnats, plant gnats, house plant gnats

About this Author

Emma Gin is a freelance writer who specializes in green, healthy and smart living. She is currently working on developing a weight-loss website that focuses on community and re-education. Gin is also working on a collection of short stories, because she knows what they say about idle hands.