How to Treat Fungus Gnats Naturally
Fungus gnats are tiny, annoying and somehow always appear right when you are feeling smug about your plant collection. The little black flies are mostly a nuisance, but their larvae live in moist soil and can become a problem if numbers build up. The good news is that fungus gnats can usually be managed naturally by changing watering habits, trapping adults and making the soil less inviting. Browse our plant care tools for helpful pest and care accessories.
The first step is to let the top layer of soil dry out. Fungus gnats love damp, organic potting mix, especially when plants are watered too often. Most indoor plants do not need constantly wet soil. Check the soil before watering, and use a soil moisture meter if you struggle to tell whether the pot is still damp below the surface.
Sticky traps are one of the easiest natural control methods for adult gnats. They will not fix the larvae in the soil by themselves, but they reduce the number of flying adults and help you monitor whether the problem is getting better. They are especially useful when combined with better watering habits.
Next, check the potting mix. Old, compacted or constantly wet soil can make fungus gnats worse. If the mix smells bad, stays wet for too long or has broken down badly, repotting into a fresh, well-draining mix may help. Read our guide on ideal potting soil for indoor plants.
Drainage matters too. If your pot has no drainage holes, water can sit around the roots and keep the soil damp for too long. That is basically a fungus gnat welcome mat. Read our guide on why indoor plant pots should have drainage holes.
Bottom watering can help in some cases because it allows the plant to drink from below while keeping the top layer of soil drier. This is not suitable for every plant all the time, but it can be useful while you are trying to break the fungus gnat cycle.
Avoid adding extra organic material to the soil while you are treating gnats. Things like composty top dressings, old leaves and constantly damp moss can keep the surface too inviting. Remove fallen leaves, tidy the pot surface and keep the area around your plants clean.
Do not panic and overcorrect by letting every plant become bone dry. Some houseplants, such as ferns and calatheas, do not like drying out completely. Instead, adjust watering to suit each plant. If yellow leaves appear, check our guide on why plant leaves turn yellow to make sure you are not creating a new problem.
For recurring fungus gnats, look at your whole plant setup. Crowded plants, poor airflow and lots of wet pots can keep the problem going. Browse our Essential Plant Care Starter Pack or our broader indoor plants if you are refreshing your setup.
The natural fungus gnat fix is simple but not instant: dry the soil surface, trap adults, improve drainage, refresh bad soil and stop overwatering. Keep at it for a few weeks and you should see numbers drop. Tiny flying pests are annoying, but they are usually beatable without going full chemical warfare in the living room.