Sick of little black flies swarming your soil? Fungus gnats are the uninvited house-party crashers of indoor gardens. They pop out of potting mix, tap-dance round your face, and lay eggs that hatch into root-eating grubs. Left unchecked, they stunt growth, invite root rot and turn plant parenting into a never-ending slap-fest.
Good news: you can evict them without fogging the lounge in harsh chems. Below are seven proven tactics—tested in real Aussie loungerooms—that tackle adults and larvae for long-term control.
Check out our complete range of Fungus Gnat Control
1) Let the top 2 cm dry between drinks
Fungus gnat eggs need moisture to hatch. Stretch watering intervals—or switch to bottom watering—so the top layer crusts over like the Nullarbor in summer.
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How to check: Poke a wooden skewer in, or use a moisture meter; if it’s dry halfway down, water from below.
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Fast win: Many growers see gnat numbers halve within a week once the “dry cap” habit sticks.
Why it works: A dry crust removes humidity and oxygen at the surface, so larvae fail and adults look elsewhere to lay.
2) Deploy sticky traps as first defence
Those bright yellow cards mimic the wavelengths plants reflect—irresistible to adult gnats.
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Hang traps just above soil and swap weekly.
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Use them alongside larval control to break the cycle.
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Bonus: They’re a monitoring tool—when cards stay clean, you’re winning.
3) Top-dress with Gnat Bat (horticultural silica)
A 5 to 10 mm layer of Gnat Bat creates a hostile, shifting barrier adults can’t burrow through.
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Apply after watering for an even layer across every pot. You can also move it to the side to avoid it getting wet or bottom water.
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Perks: Reflects light upward (deterring shore flies) and looks tidy.
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Low-maintenance: Lasts for months and won’t alter pH.
4) Hit larvae with T Drops (formally called Tanlin aka NilNat)
Your secret weapon is T Drops
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Add 1 drop per litre, stir in well.
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Water as normal; T Drops coats the root zone and the grubs ingest it.
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Re-apply every second watering for 8 weeks to catch late hatchers.
Odourless, plant-safe and hydro-friendly—from monstera in moss poles to peppers in TurboDirt.
5) Introduce beneficial nematodes (Steinernema feltiae)
For organic purists keen on nature’s micro-warriors, S. feltiae hunts fungus gnat larvae in the root zone.
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Mix the sachet with de-chlorinated water and drench thoroughly.
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Best at 18–28 °C media temps.
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Repeat monthly for stubborn cases.
6) Repot into a well-draining mineral blend
If your mix stays wetter than a Melbourne winter, gnats will linger. Aim for ~70% mineral aggregate (pumice, zeolite, volcanic basalt, gypsum, limestone) and ~30% premium organic matter.
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Improves aeration and speeds dry-down.
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Minerals hold nutrients without getting boggy.
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Stronger roots = fewer gnat invitations.
In side-by-side tests, plants in mineral-rich blends showed faster root recovery and no gnat activity after four weeks.
7) Sanitation & quarantine: keep ’em out
Prevention beats cure.
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Inspect new plants before they cross the threshold.
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Bin soggy saucer water—larvae can wriggle across puddles.
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Vacuum fallen leaves; decomposing bits are a gnat buffet.
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Rotate sticky traps monthly even after you’re clear.
Combine & conquer (your 2-week plan)
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Today: Set sticky traps; start “dry cap” watering; add Gnat Sand.
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Next watering: Dose with T Drops / Tanlin.
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48–72 h: Release nematodes if infestation is stubborn.
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Week 2: Repeat T-Drops; refresh traps; prune damaged leaves.
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Next repot: Switch to mineral-rich mix.
Why it works:
Traps thin the adult herd, T Drops and nematodes wipe out larvae, dry soil surfaces and Gnat Bat block new egg-laying, and the mineral mix removes the soggy conditions gnats love.
The proof is in the (gnat-free) pudding
Dry your soil, trap the flyers, sand-bag the surface, unleash BTi or nematodes, upgrade your mix, and keep things tidy. Do that and you’ll be sipping a cuppa beside lush, gnat-free greenery in no time.
Don’t put up with pesky flyers another day. Check out our complete range of Fungus Gnat Control products to go Gnat-Free today!
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