Fungus Gnat Be Gone Guide

Tips & Tricks

Jul 17

What is a Fungus Gnat? How can it affect my plants/home?

Fungus Gnats are very small black bodied pests (think fruit fly size) that survive off of organic matter such as potting soil, fungi, and decaying plant roots. One female can lay up to 300 eggs a day, meaning they can quickly multiply and become quite the nuisance. Luckily though, the lifespan is only about 2 weeks in total, meaning you can quickly rid your home of them.

Why you have fungus gnats, common misconceptions, and how to avoid them.

Fungus gnats thrive in darker, consistently moist areas. The easiest way to avoid fungus gnats is to let your soil dry between waterings. Having well draining soil, terra cotta pots, and avoiding overwatering can all help the soil dry out between waterings. This does not mean you shouldn’t water thoroughly. It’s often thought that thoroughly watered soil attracts fungus gnats, but as long as that soil is drying between watering days and getting oxygen to the roots it will not be a viable habitat for the fungus gnat.

For the plants that dislike dry soil for any amount of time, sticky traps are going to be your best friend. Sticky traps that can be placed into the pot of your plant will help safeguard your plant from being an egg breeding ground, this will help drastically reduce your fungus gnat population.

Side Note: Fungus gnats cannot live in water, any propagations or plants in hydroponics will not suffer from fungus gnats. If you have plants that may thrive in LECA (Lightweight Expanded Clay Aggregate) this could be the perfect time to try it out!

How to get rid of them for good, and what NOT to try.

The one product I've found that will rid your plants of fungus gnats for good is Mosquito Bits. Since it kills all the developing gnats larvae, once the life cycle of your current adult gnats ends, there won’t be any reinforcements.

Mosquito Bits recommends sprinkling the product onto the top of the soil, then watering thoroughly so that the product can work its way into the soil. Alternatively you can dissolve some mosquito bits into your water before watering, or you can add the mosquito bits to your soil mixture when repotting. All of these methods work to get the product to your plants soil, so that the gnat larvae will feed on it and perish. Repotting your soil is not necessary, but it may be useful if your house is very infested as it will get rid of any current eggs and fresh soil will offer more nutrients to your plant as it readjusts, potting the mosquito bits into the soil ensures no fungus gnats will be able to successfully inhabit the soil again.

Other methods that are common, but I don’t recommend, include adding large quantities of cinnamon to your soil, watering with hydrogen peroxide and using diatomaceous earth. These methods can sometimes have adverse effects to the health of your plant, and in my experience, tend not to be very effective.

What you need to get rid of your gnats: