Natural fungus gnat control, honestly rated

Letting the soil surface dry between waterings

Removes the moisture eggs and larvae need to survive. Extension sources consistently list this as the foundation of control — not a supplement to it.

Bti (Bacillus thuringiensis israelensis)

A naturally occurring soil bacterium sold as Mosquito Bits or Gnatrol. It targets fly larvae specifically and is used in organic growing operations. A drench is itself a watering event — apply it in place of a scheduled watering, not on top of one, so you're not undoing the dry-soil habit while treating larvae.

Beneficial nematodes (Steinernema feltiae)

A microscopic parasitic worm that actively hunts fungus gnat larvae in the soil. Needs consistently moist, temperature-appropriate soil to survive and work. They're a live product with a short shelf life — buy from a supplier that ships them cold, apply promptly, and expect a higher cost per treatment and less retail availability than Bti.

Yellow sticky traps

Well-supported specifically for monitoring and knocking down egg-laying adults — that's the claim, not elimination. On their own, traps don't touch eggs or larvae already in the soil, so a clean-looking card doesn't mean the pot is clear.

Sand or grit top-dressing

A dry, mineral surface layer is a plausible deterrent to egg-laying and helps the very top of the mix dry faster, but it's a supplementary, preventive step, not a documented larvicide — use it after larvae numbers are already down, not as a first-line treatment.

Cinnamon on the soil surface

Cinnamon has mild antifungal properties, which may reduce the fungal food source larvae feed on. It is not a larvicide and won't stop an established infestation on its own.

Vinegar traps

Apple cider vinegar traps are built for fruit flies, which are drawn to fermentation. Fungus gnats respond far more to yellow color than to vinegar, so catch rates are typically low.

Diatomaceous earth (food-grade) on the surface

Can help desiccate insects it directly contacts on a dry surface, but it loses effectiveness once wet — which is often exactly when fungus gnats are breeding.

Essential oils (neem, cinnamon, etc.) as sprays

Widely recommended online with little houseplant-specific evidence behind the claim. Neem's clearer, better-supported use is as a broader-spectrum insecticidal soil drench, not a fungus-gnat-specific fix.