To get rid of gnats (fungus gnats) in plants, especially houseplants, you can follow these effective steps:

1. Adjust Watering Habits

• Water plants less frequently and allow the soil to dry out between waterings. Fungus gnat larvae thrive in damp soil where fungi and algae grow, so drying the soil interrupts their lifecycle

2. Use a Gravel or Grit Mulch

• Cover the soil surface with a 1cm-thick layer of gravel, grit, or decorative glass pebbles. This prevents adult gnats from laying eggs in the soil

3. Employ Sticky Traps

• Place yellow or green sticky traps near the soil surface to catch adult gnats and reduce their population. Green sticky traps may be more effective indoors, but yellow traps work well too

4. Apply Natural Fungicides

• Sprinkle ground cinnamon on the soil surface or water plants with chamomile tea diluted with water. Both cinnamon and chamomile act as natural fungicides, killing fungi that gnats feed on, making the soil inhospitable to them

5. Use Hydrogen Peroxide Solution

• Water plants with a mixture of 1 part hydrogen peroxide to 4 parts water. This kills gnat larvae in the soil without harming the plant. You’ll see bubbling when it’s working

6. Use Biological Controls

• Consider using beneficial nematodes (Steinernema feltiae), predatory mites, or rove beetle larvae if you have many plants. For home use, nematodes are practical. Alternatively, use Bacillus thuringiensis israelensis (Bti) products like mosquito dunks or bits, which kill larvae when watered into the soil

7. Additional Methods

• Potato slices can be buried just beneath the soil surface to attract and trap larvae. Remove and discard the potato pieces after a few hours to reduce larvae numbers

• Neem oil sprays can be used daily for one to two weeks to control severe infestations

Summary

• Let soil dry out between waterings.
• Cover soil with gravel or grit.
• Use sticky traps to catch adults.
• Apply cinnamon or chamomile as natural fungicides.
• Treat soil with hydrogen peroxide solution.
• Use biological controls like nematodes or Bti.
• Use potato slices to trap larvae.
• Consider neem oil sprays for heavy infestations.

Combining several of these methods and repeating treatments for a few weeks will effectively eradicate fungus gnats from your plants