If you’ve noticed tiny flies hanging around your favourite fiddle leaf fig or trailing off your spider plant, you’re likely dealing with fungus gnats.
These common houseplant pests are more annoying than harmful but, in large numbers, they can damage your plants and test your patience.
Luckily, there are plenty of safe, effective ways to keep them under control. We asked the experts how to deal with houseplant flies without harming your greenery (or sanity).
How to get rid of fungus gnats (houseplant flies)
Adjust your watering routine
Pest control expert Tony King, owner of The Pied Piper, says the first step is simple: let your soil dry out. He explains: “Overwatering is the major cause of infestation, as larvae need moist soil for survival. I recommend allowing the top 2 inches of soil to dry out between waterings, thus interrupting the life cycle of the gnats.
“Bottom watering [placing your pot plant in a container of water to allow soil to soak up moisture from below] keeps the surface soil drier and less attractive for egg deposition. Drainage of your pots and well-aerated, fast-draining soil – e.g. incorporating perlite or sand – also helps alleviate moisture.”
Use natural remedies that really work
Yellow sticky traps work well to trap adult gnats. “These are very effective because adult gnats are attracted to the colour yellow,” he explains. “Cider vinegar traps would be another method of adult control – fill a small dish with apple cider vinegar, plus a couple of drops of dish soap to attract them."
But, he warns, “even though these methods will effectively suppress the adult population, they do not work to eradicate the larvae nested in the soil, which is the true source of the problem.”
He also recommends natural treatments like Bacillus thuringiensis israelensis (BTI), which are found in products like Mosquito Bits or Microbe-Lift. “The treatment is safe for plants, pets, and humans but lethal to larvae.”
Get to the root of the problem
Gardening expert Luke Dejahang, CEO of Crown Pavilions, agrees that adjusting your watering routine is key. “Letting the soil dry out … can disrupt their life cycle,” he says. “Watering houseplants from the bottom ensures that the top layer is kept dry, but the houseplant itself is watered and hydrated, making it less attractive for these fungus gnats to lay eggs.”
Luke also recommends using neem oil as a natural remedy. “Neem oil is a natural insecticide that can be used as a soil drench or spray to kill gnats and their larvae. It's safe for most plants and beneficial insects, making it a great eco-friendly option for pest control.”
And remember, small changes make a difference
Charles Whitehead, director of Pearl Lemon Properties, adds that small changes can make a big difference to your home, too. “It is important to modify irrigation methods since fungus gnats thrive in overwatered soil. Their reproductive cycle is interrupted if the soil is permitted to dry fully in between periodic waterings.”
He suggests trying cinnamon powder as a natural anti-fungal deterrent and reiterates that a diluted hydrogen peroxide solution (1 part 3% hydrogen peroxide to 4 parts water) is a fast, plant-safe solution. Just be sure to use with relevant safety precautions e.g. gloves.
“Such simple fixes not only preserve your plants but also help to create a healthy living space,” he says.
Natural pest repellent
