DIY ideas to rid your indoor plants of fungus gnats | Pest and Disease Control | Gardening Australia

Fungus Gnats are the bane of many gardeners with indoor plants, especially over the cooler winter months. Jane gives us some tips on how to avoid a gnat attack at your place, and what to do if you already have these unwelcome house guests

As they say in the classics, prevention is always better than a cure, here are some tips to avoid a full-on “Gnat Attack”.

02: 30 | Don’t overwater
Excessive watering can lead to the growth of algae in saucers and on the surface of the soil which fungus gnats will feed on. This is particularly important overwinter, when the irrigation requirement from indoor plants is much lower than other seasons. Overwatering can also lead to weakness or rot in plant roots, making them “soft targets” for fungus gnat larvae.

While a wet soil can be a haven for Fungus Gnats, there are a couple of soil drenches that can be used to eliminate populations that are already in the soil.

03:00 | Soil Drench
Apply a Neem-Oil based soil drench to the affected pots at a rate of 30ml per 10L of water, using about 1L of the mixture per 25cm pot. Repeat weekly for three weeks.
Gnat-loving Nematodes– Just as we dislike the fungus gnats, there is a particular strain of entomopathogenic (insect killing) nematode that just adore them and will make short work of an infestation at your place. Available at some nurseries commercially, these nematodes are applied as a soil drench, and a standard sachet will treat 24 x 25cm pots. Two treatments, a week apart, is all that is generally required to nip your gnat problem in the bud, and these nematodes won’t harm pets, plants, people or beneficial bugs and bacteria.

Remember, you can only use one of these methods, as the Neem-Oil drench may kill the beneficial nematodes also.

03: 42 | Sticky Traps
While store bought yellow sticky traps will work to attract and trap the adult gnats, why not fight gnats with nature, and pop a couple of carnivorous Butterworts (Pinguicula sp.) or Sundews (Drosera sp.) around the house. These gorgeous plants are the living equivalent of fly paper, and use their sticky leaves to lure, trap and digest insects, including fungus gnats.
Mulch your pots – A layer of inorganic mulch like aquarium stones or small pea gravel across the surface of the pots is an effective way to both discourage infestation and break the lifecycle of existing fungus gnats. This mulch layer prevents the females being able to lay eggs in the soil, and the adults from emerging once mature.

We know they can be a real problem for both plants and people, but with these top tips, you can say farewell to freeloading fungus gnats at your place once and for all!

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