How to Get Rid of Fungus Gnats on Houseplants
Fungus gnats have a real knack for annoying houseplant owners. Here's how to banish them for good—without using harmful pesticides.
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Proven Ways to Eliminate Fungus Gnats
“I had a fungus gnat explosion on my overwintering geraniums. Is there an effective, natural way to eliminate fungus gnats other than neem oil? And is neem oil actually a safe solution?” asks Birds & Blooms field editor Sue Gronholz.
Horticultural expert Melinda Myers writes, “Neem is labeled for controlling fungus gnats on houseplants and should not damage the plant when the directions are followed. But understanding how these insects enter our homes and affect our plants will help with control.
Fungus gnats find their way inside by hitching a ride on plants added to our indoor houseplant collection, on plants moved inside after a summer outdoors, or on organically rich, non-pasteurized soil. Fortunately, fungus gnat populations on houseplants seldom reach plant-damaging levels. They are, however, very annoying.
Fungus Gnat Control: Watch Your Watering
Start your fungus gnat control by adjusting your watering practices. Since these gnats thrive in moist soil, avoid overwatering. Allow the top few inches of soil to dry between thorough waterings, and pour off excess water that collects in the saucer to avoid overly wet soil and root rot.
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Organic Fungus Gnat Treatment
If this alone is not working, treat the soil with an organic Bacillus thuringiensis israelensis (BTI) product, such as Summit Mosquito Bits, labeled for controlling fungus gnat larvae on houseplants. You’ll need to make several weekly applications to manage the existing population, and to apply again if new fungus gnat populations appear.
Just sprinkle the mosquito bits on the soil surface and water. When the wormlike fungus gnat larvae feed upon the Bti, they die. Best of all, the product is safe for pets, people and wildlife.