Gnat Extinction - Ask Extension
How do I get rid of many gnats in my household plants?
Knowledgebase
Gnat Extinction #914499
Asked August 18, 2025, 5:39 PM EDT
How do I get rid of many gnats in my household plants?
Denver County Colorado
Expert Response
I have tried a Katchy which has a sticky pad on bottom of machine that has an ultraviolet light and fan to get them in the machine. I have put hydrogen peroxide and water mixture to kill gnat eggs in all my plants and sticky tabs. There are less but they are still present in the soil of my plants.
Sorry to hear about your gnat problem, I know that can be very annoying. While there is not just a one in done solution here are some additional ideas:
Our full fact sheet on this topic is located here:
Fungus Gnats as Houseplant and Indoor Pests | Colorado State University Extension Website
Fungus gnats love water, so it's important to monitor your watering. Often times overwatering provides a perfect environment for gnats to thrive, letting the top 1 inch or so of your plant to dry out between watering.
Sounds like you have already taken this step, but you may need to re-apply: While traps help control the adult population of fungus gnats, you still need to treat the eggs and larvae in the soil. Make a solution by mixing 1 part hydrogen peroxide and 4 parts water, then pour the mixture into the soil, making sure to completely saturate the soil but avoid getting the solution on leaves.
One simple trick to help prevent fungus gnats from laying their eggs is to block their access to the soil such as a layer of sand, about 1/4" on top of your soil.
If you are still having issues, please review the fact sheet linked above for some additional treatment options.
Our full fact sheet on this topic is located here:
Fungus Gnats as Houseplant and Indoor Pests | Colorado State University Extension Website
Fungus gnats love water, so it's important to monitor your watering. Often times overwatering provides a perfect environment for gnats to thrive, letting the top 1 inch or so of your plant to dry out between watering.
Sounds like you have already taken this step, but you may need to re-apply: While traps help control the adult population of fungus gnats, you still need to treat the eggs and larvae in the soil. Make a solution by mixing 1 part hydrogen peroxide and 4 parts water, then pour the mixture into the soil, making sure to completely saturate the soil but avoid getting the solution on leaves.
One simple trick to help prevent fungus gnats from laying their eggs is to block their access to the soil such as a layer of sand, about 1/4" on top of your soil.
If you are still having issues, please review the fact sheet linked above for some additional treatment options.
