How to eliminate gnats from your houseplants

Last updated on January 2nd, 2026 at 02:37 pm

How to eliminate gnats from your houseplants. Fungus gnats are a big problem for most people who want indoor plants. In order to eliminate them, we must first find out where they come from.

Where do fungus gnats come from?

Fungus gnats come from moist soil, leaky drain pipes, overripe fruit, and especially around plants that do not drain well. You have undoubtedly seen them circling your potted plants, indoor trash cans, and decaying matter. They are attracted to moist conditions.

The first thing to do is ensure your plant containers are draining well. Check the holes under your pots, are they plugged? If so poke your finger or a pencil to clear the debris in the hole. It’s amazing how many times this little procedure helps alleviate fungus gnats and root rot.

Will insecticides work?

Spraying with an insecticide will work but the problem is the adult gnats have already laid their eggs in the soil or surrounding area. The main problem is that the spray insecticide will kill the flying gnats but not the larvae that are hidden in the soil.

The larvae pupae will develop into an adult in 4 maybe 5 days this means a new swarm of gnats swarming around your houseplants and inside your home. So…your spraying again and killing the newly hatched gnats is good but the cycle repeats itself again, and again.

How to kill gnat larvae in the soil?

You can use a systemic insecticide to target and eliminate the larvae effectively. This type of insecticide works by being absorbed into the plant through the soil. Simply apply the product directly to the soil around your plant, then water thoroughly to help it soak in. As the larvae feed on the plant’s roots, they’ll ingest the chemical, which ultimately kills them.

This method ensures the treatment gets right to the source, minimizing the chance of missing any hidden larvae. It is best to spray once again to remove any gnats that might still be flying around. Bonide systemic control is a good solution to killing gnats in your soil. Ask for it at your nearest neighborhood Garden Store,

Gnats flying around a plant

How to eliminate gnats from your houseplants — Gnats flying around a plant

What about organic products?

Use BTI (Mosquito Bits^®)in the soil it is an organic bacteria product that you apply to the soil that will kill these tiny insects. Sticky fly traps will also do the trick for gnats flying around, but of course not the larvae in the soil. You can also apply neem oil to the soil to kill the larvae, but make sure to dilute the solution at about half the ratio. Here is a great post on how to use these products in your home. Get rid of fungus gnats.

Some gardeners swear by a simple, low-cost method for controlling fungus gnats using raw potato slices. Fungus gnat larvae live in the top layer of moist soil and feed on organic matter. When you place thin slices or small chunks of raw potato directly on the soil surface, the larvae are attracted to the starch in the potato.

Over time, the larvae migrate into the potato pieces and begin feeding inside them. This effectively traps the larvae and removes them from the soil. Check the potato slices every day or two. Once you see larvae or notice the potato beginning to break down, remove it promptly, seal it in a plastic bag or container, and dispose of it in the trash. Replace with fresh potato pieces as needed until activity slows.

To control adult gnats, use yellow double-sided sticky cards placed just above the soil surface or near the plant. These traps capture flying gnats before they can lay more eggs, helping break the life cycle. For best results, combine both methods: potatoes to target larvae in the soil and sticky cards to reduce the adult population.