How to Naturally Get Rid of Gnats on a Houseplant

Protect houseplants from gnats using natural methods.

Gnats flying around your houseplants can be pesky. It's the larvae of the fungus gnat, however, that are harmful. The larvae feed on your plant's roots causing the leaves to yellow and wilt. Gnats are drawn to moisture and decaying organic matter in the soil and a large infestation can kill a plant. For an organic, chemical-free household, using pesticides to eliminate gnats is not an option.

Things You'll Need

• Planting pot
• Potting soil
• Sticky traps

Instructions

1. Reduce the frequency of watering your houseplants at the first sign gnats. Allow the plants to sit until the top inch of soil is dry to the touch. For houseplants in large pots or tubs, let the top 2 inches dry out before watering.

2. Soak the plants completely when you do water, applying water until it drips out the drainage holes in the bottom of the plant. One to two hours after watering, remove any trays under the pots and discard accumulated water before replacing under the planter.

3. Remove any decaying plant material from the planter and those near the affected plants. Collect and discard dropped leaves, wilted flowers and any bulbs that have died back. Quarantine plants that appear severely infested by placing them in a separate room or a sun porch, away from other plants.

4. Examine the pot's soil. If it is waterlogged or if the plant has been in the same pot for longer than a year, it is time to repot into a larger planter. Brush soil from the old pot away from the houseplant's roots before planting in fresh, new potting soil.

5. Position yellow sticky traps around the plant. Set the adhesive-covered cards on the windowsill, plant stand or table where the plants sit. The gnats will be drawn to the yellow color and become stuck to the adhesive. Throw away the cards routinely and set out fresh ones until they no gnats are left to capture.

Tips & Warnings

• Bacillus thuringiensis H-14 is typically considered a natural bacteria. It specifically targets fungus gnat larvae, and may be applied according to the manufacturer's instructions in cases of severe infestation.

• If gnats are not eliminated by natural methods, discard the houseplants.

References

• University of Minnesota Extension: Houseplant Insect Control
• Colorado State University Extension: Fungus Gnats as Houseplant and Indoor Pests
• Washington State University: Fungus Gnats (Houseplants)