Lava-Lite No Gnats - Natural Volcanic Rock Barrier for Fungus Gnats
Best for: growers dealing with fungus gnats (sciarid flies) who want a chemical-free way to break the breeding cycle.
Our thoughts
Fungus gnats are one of those problems that make new growers panic, and this is a genuinely simple fix - no sprays, no chemicals, just a layer of volcanic rock that stops adult gnats laying eggs in the first place. It won't work overnight, but it's honest about that, and it's cheap enough to just keep on hand.
Lava-Lite No Gnats is a 100% natural, mineral-based mulch made from volcanic rock, designed to control fungus gnats (sciarid flies) without pesticides. Rather than killing adult gnats directly, it works as a physical barrier: a 12-20mm layer spread across the surface of your growing medium stops adult gnats reaching the soil to lay eggs, and stops any larvae that do hatch from escaping to complete their life cycle.
Because there's no active chemical ingredient, it's non-toxic and safe around children, pets and aquatic life, and it doesn't break down or wash away the way some organic mulches do.
How it compares
No Gnats takes a different approach to most fungus gnat products on the market.
- Unlike BASF Nemasys, which uses live Steinernema feltiae nematodes to actively hunt and kill gnat larvae in the soil, No Gnats works as a passive barrier that stops the breeding cycle at the surface
- Cheaper upfront than a Nemasys nematode pack, though it works on a different timescale - expect 8-14 days to break an existing infestation rather than an immediate kill
- Reusable as a permanent mulch layer rather than a one-off biological treatment that needs reordering every few weeks
Combine the two if an infestation is already established - Nemasys deals with existing larvae while No Gnats stops the next generation from breeding.
Usage guidance
Application
Spread a 12-20mm (roughly half to three-quarter inch) layer of No Gnats evenly across the surface of your growing medium, right up to the base of the stem.
Timeline
Give it 8-14 days to break the fungus gnat life cycle - existing adults die off naturally but can't lay new eggs once the barrier is down.
Top-ups
Top up the layer if it gets disturbed by watering or repotting, since the barrier only works while it's covering the surface.
Technical specifications
- Brand: Lava-Lite
- Active mechanism: physical barrier (non-chemical)
- Material: natural volcanic rock
- Application depth: 12-20mm surface layer
- Time to control infestation: 8-14 days
- Safety: non-toxic, child and pet safe, contains no pesticides
- Sizes available: 1 litre, 3 litre
Who this is for
- Growers with an active fungus gnat problem who want a non-chemical fix
- Houseplant owners who want a safe, pet-friendly barrier method
- Anyone wanting to prevent gnats before they establish, as a standing mulch layer
- Growers happy to pair it with a biological nematode treatment for faster results
Our take
No Gnats won't solve a bad infestation overnight, but as an ongoing barrier it's about as low-risk and low-effort as fungus gnat control gets. For the price, there's no real downside to having a layer of it on every pot.
Does exactly what it should, day in, day out.
