Tiny Flies in Soil? (Fungus Gnats)
Gnats breed in wet media; larvae feed on roots and slow growth.
Fungus gnats in cannabis? Tiny flies, larvae eating roots—see fixes and analyze fast.
Common Causes
- Constantly wet topsoil
- Organic-rich media staying soaked
- No sand/mulch barrier
How to Tell Which One You Have
Small black flies, larvae in top inch; wet soil; seedlings stunt.
FAQ
Fix?
Dry top inch, sticky traps, BTi drenches.
Topdress sand?
Yes, or perlite layer to deter laying.
Hydrogen peroxide?
Can knock larvae; don’t overuse.