Houseplants are a gift – until tiny black flies crawl out of the soil and buzz around the living room as if they were planning world domination. Welcome to the world of fungus gnats – they are annoying, they reproduce quickly, but: you can get rid of them. And naturally so.
What are fungus gnats – and why this name?
Fungus gnats look like fruit flies in black and get their name because they somehow... appear subtly gloomy. Dark-colored, barely 2–5 millimeters in size, but with a mission: nibbling on roots and producing offspring in the potting soil.
It's not the flies themselves that are the problem – but their hungry larvae. They live in the pot and feed on tender root tips. This can be especially critical for young plants, seedlings, or cuttings.
How can I recognize an infestation of fungus gnats?
Besides the classic scene ("swarm of flies over the philodendron"), there are a few clear signs:
- Small black gnats when watering or on the windowsill
- The soil feels moist – even though you water less often
- The plant grows poorly, lets leaves droop, or appears "listless"
- You find transparent larvae (with black heads!) in the topsoil
But don't panic: a few flies are no reason to mourn – rather to take action.
Get rid of fungus gnats – but please with style
🪴 1. Watering: less is more
Fungus gnats love moist soil – a true wellness area for their larvae. So: let the top layer of soil dry out well before you water again. That alone slows them down a lot.
🟡 2. Yellow boards: The disco trap for mosquitoes
Hard to believe, but: The little flyers are totally into yellow. Stick a yellow board into the ground – the sticky thing works wonders. It catches the adult mosquitoes before they lay new eggs.
🐛 3. Nematodes: Mini avengers with a bite
Sounds like sci-fi, but it's pure nature: SF nematodes (Steinernema feltiae) are tiny roundworms that specifically eat the larvae of fungus gnats. Simply apply with the watering water – and the micro-army gets to work. Super effective, completely non-toxic.
☕ 4. Home remedies with humor (and effect)
- Cinnamon: A pinch on the soil acts as a fungicide – and fungi love fungus gnat larvae.
- Matches: Stuck headfirst into the ground, they are supposed to release sulfur – the larvae don't like that at all.
- Sand or expanded clay as a mulch layer: A dry cover that no mosquito likes to crawl through.
And no: coffee grounds don't help here – they often just make the soil wetter and more attractive.
What to do with persistent infestation?
Sometimes nothing helps – and the infestation is persistent. Then this helps:
- Remove the plant from the soil, rinse the roots, place in new, dry soil
- Clean pots well beforehand (including the coasters!)
- Potting soil should focus on quality in the future – pre-steamed or sterile soil is less attractive to gnats
Tip: Hydroponics or AIRY systems with substrates like expanded clay are significantly less susceptible.
Mosquitoes go, plants stay
Fungus gnats are annoying – but not a disaster. With a bit of patience, an arsenal of home remedies, and possibly biological helpers, you will get rid of them. And all without chemical weapons. In case of doubt, we always gladly recommend the products from our friends at Plantura. You can find them here.
So no mourning for fungus gnats – but rather joy in fresh air and healthy plants.
