Repotted some indoor plants with bagged soul from Bunnings (should’ve known better) and now I’ve got a small infestation of these little bastards. Currently isolated to just the 3 pots that the soil was used in, but im worried they’ll spread – the pots are outside now under cover.
What are the guaranteed ways to get rid of Fungus Gnats?
I’ve sprayed the soil heavily with neem oil, and I’ll be off to buy the sticky traps tomorrow. I keep reading about soaking “mosquito bits” in water, but the product isn’t available in Australia. Hydrogen Peroxide 3%, mixed 1:4 with water comes up as an alternative, but I’ve read some mixed reports.
Also, am I at risk of them spreading into the garden outdoors, or are they exclusively an indoor pest?
by mickdundeee
9 Comments
All insects are technically outdoor creatures because houses used not to exist 😀
So I read on this group actually you can put a layer of gritty sand on the soil and it makes them go away by stopping the breeding cycle. I tried this in one pot and I must say, it’s worked! 🥳
The other thing you can do which helps most of them but not every plant – because some need regular watering – is to let the soil dry right out. You can’t really do that for something just repotted though, so give sand a crack.
There are nematodes that can kill them.
For me, the guaranteed fix has been mosquito bits (soaked for 30 mins in water and then the used to water plants). I purchase from a large online retailer.
I have this problem all the time and it doesnt matter where you buy the potting mix or how much you spend! I repotted amd got am absolute infestation.
I have found that they do spread to outdoor pots.
They are awful – your plants wont die they just wont grow as they eat all the tiny roots.
I actually sprayed last ibfestation with fly spray. It was so bad.
Neem needs a soil drench. Has to be saturafed.
There is also somethi g valled fungas gnat barrier – it is small rocks that go on top and they cant get out then. (So die eventually)
If you can bottom water them for a while. They lay eggs near the surface of the soil but don’t like it dry.
I had the same problem recently with Bunnings soil. I vacuumed as many up as I could over a few days and only bottom watered. Noticeably less of them now. Hoping I’ve broken their lifecycle enough to fully exterminate.
Econeem helps
I changed all my soil indoors for a mix of coir, peat and perlite. Haven’t seen a single fungus gnat since!
I’ve found Tanlin drops to be very effective. A bottle is pricey (iirc I paid about $40 for a 20mL bottle), but you only need 1 drop per 2L of water, so that bottle goes a long way. I mix it into the water I use to water my plants with, and it sorts out my fungus gnat issues very quickly. Haven’t had to use it recently because the gnats aren’t there atm.
Just plant them in coconut coir and use liquid or slow release fert. You dont want composting soil indoors.