Much as I love keeping indoor plants, and as much as I still need to learn about keeping them alive and thriving – seriously, I had no idea it would be more complicated than watering every so often – my greatest challenge so far has been fucking fungus gnats! Clouds of them have prowled my house like a street gang from the 80s, searching for an unsuspecting and vulnerable plant to demolish.

What are fucking fungus gnats?

If you know what these fuckers are, then you probably hate them as much as I do. If you don’t know what these fuckers are, then prepare yourself to hate them as much as I do.

Fucking fungus gnats (FFGs) are little flies that resemble fruit flies or mosquitos and have the same preternatural knack for vanishing as soon as you try to swat them out of the air.

They plant their evil, sap-sucking babies in the soil around plant roots and as they hatch from their rotten eggs and squirm about in the dirt, they latch onto those delicate roots and suck the life out of your precious plants.

They prefer moist soil, so if you’re watering your plants to, you know, keep them alive, you’re also sustaining the life cycle of these parasitic fucking vampires.

Once they’re grown, they’ll wriggle free of the dirt and start flying around the house in search of fresh plants for the next generation to consume. And you’ll know they’re there. They’re that flicker of a shadow you see out of the corner of your eye at first. Then you’ll catch yourself absently swatting around your face when you accidentally walk through a fucking CLOUD of them somewhere in your house.

You’ll find them drawn to your devices at night – you know, when you’re scrolling through Esty instead of sleeping. You’ll go to take a sip of your tea and find one or more of the fuckers floating in there since your last sip.

You will know when you have an infestation of fucking fungus gnats.

Where do fucking fungus gnats come from?

I haven’t brought home a house plant from a shop in weeks that didn’t have something in the soil already. This, my fellow plant-loving friends, is really depressing and demoralising. But it’s not the fault of the outlets or the suppliers – those fucking fungus gnats are just doing what fucking fungus gnats do – living out their parasitic life cycle however they can.

This doesn’t mean we should feel sympathy for them – we should still try to destroy them whenever and wherever we can!

The thing is, fucking fungus gnats will most likely invade through the potting mix or potting soil. In my naiveté, I brought the worst of my infestation on myself this way, by repotting some plants with a bag already infested with the fuckers. The next thing I knew, there were clouds of them roaming my house looking for fresh sap.

So, plant keeping neophytes, learn from my mistake!

I’m not too sure what you can do to avoid buying bags of fucking fungus gnat invested potting mix, but being aware of the problem is at least part of the battle against them. Look for bags without holes in them, if possible, because unless the mix is infested before being bagged, they’ll be infiltrating the mix through those little air holes.

How do you get rid of fucking fungus gnats?

Neem oil

The most common remedy I’ve come across in my, many, many, desperate searches online is neem oil, commonly under the brand locally here in Australia, Eco-Neem. You can get it in places like Bunnings and Mitre10 – folks elsewhere in the world probably have their own equivalent hardware-type stores.

Neem oil is not squeezed from the seeds of a neem tree and shouldn’t be considered necessarily a ‘natural’ oil any more than the oil you put in your mower or your car – have you checked those levels recently, btw? You probably should.

The Eco-Neem has a little leaflet of instructions under that little corner you have to somehow peel back without tearing. The best ways to deal with fungus gnats with neem oil is to drench them.

Drenching with neem oil

It always comes down to math. Again, folks in the world who still haven’t embraced the metric system will have to reach up on the measurements in their own weird-ass systems of measurement, but where the metric system prevails, it’s 3ml per litre. The Eco-Neem comes in one of those containers where you can measure out what you need.

If, like me, you have about a hundred indoor plants you want to drench, be prepared to make a day of it!

Once you have your watering can full of water and neem oil, pour it all around the soil of your plant. To be absolutely sure, focus on the areas around the roots, but don’t skimp on the edges either. Give those fucking fungus gnat babies nowhere to go!

Unfortunately, though I have had SOME success in reducing the population of FFGs with neem oil drenches, they haven’t entirely disappeared.

Hydrogen peroxide

Another tactic in your arsenal in your war against fucking fungus gnats is something I’ve only recently learned myself – hydrogen peroxide.

My experiences with it thus far have been fairly encouraging. It’s especially gratifying listening to it fizz around the roots and knowing it’s the sound of mass fungus gnat death and destruction.

Note: I wouldn’t ordinarily advocate for the mass death of anything, but fucking fungus gnats are the only exception I can think of at present. Well, other than Nazis.

The formula for murdering fucking fungus gnats with hydrogen peroxide is to mix 3% hydrogen peroxide with water at a ratio of 4:1. That’s 4 water to 1 hydrogen peroxide.

Basically, one 200ml bottle of hydrogen peroxide to four 200ml bottles of water.

I say that only because I haven’t yet found larger bottles of hydrogen peroxide in my local area.

If you’re at all au fait with math, you’ll notice right up front that this is not especially economical for drenching, especially if you have, as I do, about a hundred plants. If you can source larger amounts of hydrogen peroxide – I just cleared out the shelf at the local Woolworths – then you may be in a better position to blitz those fucking fungus gnats in fizzing detritus dribbling out the bottom of the pot.

Be sure to enjoy that moment.

But like neem oil, this is best applied as a drench. You can, however, also use the same ratio mixture as a spray to catch those airborne fuckers. However, keep in mind that hydrogen peroxide deteriorates quickly in water and will only be good for about a half-hour or something. So don’t prepare a spray bottle to use later. Prepare it and use it straight away.

Bug spray

Airborne adult fungus gnats are about as susceptible to bug sprays as other airborne bastards like flies and mosquitos. However, you’re never going to stop every adult in the air and that’s just not going to have much impact on actually halting the life cycle. Some adults never leave the plant they’re hatched in! They just leave their nasty little babies in the same place.

Not a lot of plants appreciate being sprayed with bug spray. I’m not sure if it’s the violence of the aerosol against leaves or stems, but you should really take pity on your already stressed plants and just not blast them with an aerosol bug spray.

Squirt guns or whatever you call the spray bottle varieties, they’re a much gentler approach. I’ve been using a pyrethrum-based spray that has been pretty effective (possibly the most successful weapon on my anti-fungus gnat arsenal), but it, too, isn’t terribly healthy for the plant to be sprayed too much. I focus the spray on the soil as best I can, saturating the surface whenever I notice any adults in the area. Surfacing adults die. Adults trying to burrow in, die. Any larvae near the top also die.

For best results in getting rid of adults, you should spray every day!

For the sake of not stressing your plants, you should NOT spray every day!

Not very helpful, huh?

I can’t really offer advice here, but I just pull out the spray when I notice some wriggling and gently wet the whole surface of the soil rather than spray the plant directly. Fungus gnats may settle on the leaves, but their target is the dirt – at least as I’ve come to understand the middling little minds of those fuckers.

Make the dirt as inhospitable as possible for the FFGs but not so inhospitable that the plant wants to move out of the pot, too.

Let the soil dry out

Speaking of making the soil inhospitable, letting it dry out is another suggestion I’ve seen floating about in forums and plant keeping help sites.

This, like everything else mentioned above, can be fraught for the poor plants involved. Infested ferns are struggling enough with the FFGs without also having to go without water! I am not so experienced yet with keeping plants alive to really offer anything of any use to anyone here, but I figured I’d mention it because it’s mentioned everywhere else. Fucking fungus gnats like moist environments. If you can let your plants’ soil dry out, and your plant doesn’t mind living in dust for a while, good luck to you.

However, it was also pointed out to me by a friend who grows ferns for wholesale – I can only assume she knows all about these things – that plants under stress from lack of water will be even more stressed by a chemical drench.

Basically, don’t put a chemical drench like neem oil or hydrogen peroxide over a plant you’ve let dry out. I don’t know enough to say whether this is a real concern, but I can’t refute the logic.

Letting the soil dry out is probably the cheapest and least labour-intensive approach to discouraging fungus gnats, and if you’re prone to forgetting to water regularly anyway, this is probably the approach for you.

Cinnamon

An unexpected solution offered by Wikipedia is powdered cinnamon, which evidently acts as a fungicide. I did not know this! I’ve added it to my arsenal, and it’s proved to be surprisingly effective. Also, incredibly gratifying to watch the nasty lil fuckers squirming and flailing in the cinnamon dust.

I’ve never wanted to eat potting mix so bad in my life. I love the smell of cinnamon!

I didn’t check how much should be used and given the scope of the problem and the depth of my hatred for fucking fungus gnats, I dumped a fairly dense layer all around the top of the soil and the base of the plant, making sure not to miss any areas.

Given just how many plants I have I’ll need to buy a whole fucktonne of cinnamon to keep them all covered, so this tactic – at least for me – will probably be reserved for so-called surgical strikes on infestations rather than a preventative measure. Unless I can get cinnamon delivered by the kilo.

Verdict: effective and gratifying if you enjoy watching pests flail as they die a spicy death.

Note: You’ll only get to enjoy this spectacle if they’re already close to the surface at the time of application. Long-term success is still uncertain from my personal experience so far.

However – there’s always a but or however, huh? – keep in mind that cinnamon and water don’t naturally mix. Watering a plant with a layer of cinnamon can be fraught as the spice retards water saturation into the dirt.

I’m not entirely sure what we’re supposed to do at this point, but after leaving the cinnamon layer for a while (totally up to you exactly how long ‘a while’ is, but I’d say until next watering) start mixing it into the soil some more so that it stops being a shield against water.

I suppose another approach might be to mix the cinnamon into the potting mix at the time of repotting a plant. So, you know, a little perlite, a sprinkle of plant food, and a dusting of cinnamon.

Again, this will need more research and experimentation so your mileage may vary. If you’ve actually had some experience with using cinnamon in your war against fungus gnats, please let me know about your success or lack thereof!

Sticky traps

Fucking fungus gnats apparently like the colour yellow, so yellow sticky traps are frequently suggested. I missed the ‘yellow’ part at first and just used some cheap sticky traps of a brownish shade, but I still managed to collect a few of the fuckers.

The trick is to place them strategically to maximise your catch, so I say make your pot plant a yellow cone of shame! This is effective only against catching adults coming into or crawling out of potting soil, so odds aren’t great that you’ll get rid of them entirely all at once. However, used in conjunction with another method yellow sticky traps might hasten the process of annihilation.

Remove when there is more black/grey than yellow left on the trap, but enjoy the moment if you can before you toss it in the bin. Every FFG corpse is a victory.

DIY sticky traps

If, like me, you’d have to go well out of your way to find actual yellow sticky traps, here is a messy but potentially useful DIY apparatus of FFG slaughter.

You will need yellow paper or yellow card, and some Vaseline. And that’s it!

Apply Vaseline to the card – one side should do but if you’re extra keen, lather up both sides and stand it up in the soil of an infested pot plant. Those lil fuckers should get stuck on it as they jump out of the soil.

I haven’t tried this yet, but if you do, let me know how it goes!

Of course, if you come into possession of actual/commercial yellow sticky traps then apply them as instructed.

Natural predators

This is tricky for indoor plants, especially if you live somewhere like Tasmania – as I do – where insect predators may be considered pests and actually aren’t permitted to cross the border. I have a friend working in state biosecurity whose job it is to make sure invasive species are kept the fuck off our beautiful island, for which I am perpetually grateful.

However, there are some natural predators for managing these fucking fungus gnats that may be an option. Heck, you can actually order predatory bugs online and have them delivered to your door – unless my friend in biosecurity – hi Kate! – says they’re not welcome. Always – always! – check what’s safe where you live.

Hypoaspis [https://bugsforbugs.com.au/product/hypoaspis/] are soil-dwelling predatory mites that like eating fungus gnat larvae, so if they’re an option for you where you are, then consider fighting bugs with bugs!

Centipedes are also an interesting solution I accidentally stumbled across because I found some in one of my pot plants. They also like eating insects and their larvae!

I know some people find centipedes pretty icky, but consider the good they may be doing for your plants before you try to get rid of them. You may find that after they’re gone you’ve got a new bug fight on your hands. After all, they’ll have turned up to eat SOMETHING in your pot plants.

How to prevent fucking fungus gnats in the first place?

Regular drenches with hydrogen peroxide are apparently pretty good for plants. In fact, I just ordered a few litres of the stuff from an online store that sells a ‘plant grade’ variety of hydrogen peroxide specifically for maintaining the health of plants.

The things I’m learning as I fight to keep my plant children alive.

After the bad luck I’ve had with these fucking fungus gnats, I now drench any new plant that comes into the house, whether with neem oil or hydrogen peroxide. A good coating of cinnamon every now and then, and making damn sure I don’t leave plants standing in water should – SHOULD – help keep those FFGs the fuck out of my indoor jungle.

When buying bags of potting mix or potting soil, it’s probably worth buying something more expensive. The cheaper bags have all been infested so far in my experience. Cheaper bags seemed to have holes in them, and bugs love finding holes in damp and smelly places. Look for bags that don’t have any holes. Trust me, the higher cost will save you money and sanity in the end.

Oh, and avoid leaving an open bag out in the rain, that’s like waving a yellow flag to a fucking fungus gnat.

Make sure you don’t inadvertently invite FFGs gnats into your life by leaving water in the dishes under your plants for too long. Excess moisture is, of course, unhealthy for a lot of plants anyway (so I’m discovering) so this is probably good practice regardless. FFGs love the soggy soil and will move in quick smart.

Hopefully, my struggles will be helpful to someone. If you have another solution, short of nuking the site from orbit, please let me know!

Finally

Remember to empty any dishes under your plants!

Some plants drink best from the bottom, which is actually another approach to discouraging gnats I’ve read and heard about. But not all plants like soggy roots, and it’s the soggy root systems that the fucking fungus gnats like best.

Again, contradictory advice! It seems plant care is FULL of contradictory and confusing advice!

If water has been sitting in the dish for a while – like, a day? – dump it like a paedophile senator. It’s only going to create an ideal environment for FFG infestation – also, unhappy plants.

Good luck, and let me know how you go, however you choose to wage your war against fucking fungus gnats.