How to Control Fungus Gnats and Damping Off Organically

fungus gnat on a leaf

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Late winter and early spring is when most gardeners start seedlings indoors and get the gardening season underway. Growing your own garden plants from seed is highly rewarding and can allow you to enjoy unique or heirloom species that are not found in garden centers.

However, fungus gnats and damping-off disease can stymie even the most seasoned gardeners and seriously affect the success of growing seedlings. But before you spend money on expensive chemicals, getting rid of fungus gnats is much safer and cheaper than you would expect.

Fungus Gnats

fruit fly and fungus gnat side by side
Fungus gnats and fruit flies are DIFFERENT

Fungus gnats (Sciaridae spp.) are the most common houseplant pest, and are distinguished from Fruit flies (Drosophila spp.) because of their darker color. While fruit flies hang out primarily near fruit, rotten food and funky fridges, you’ll find fungus gnats in wet plant soil, in sewer areas, and in household drains.

They’re also attracted to CO2 (carbon dioxide) which is why they fly up right in your face.

Fungus gnat adults are about 1/8-inch long, spindly looking flies with long legs and long, thin antennae. They resemble tiny mosquitoes more than they do common flies. These tiny, black insects seem innocuous enough as they hop all over your plants.

But, while the adults rarely cause any problems, the young larvae will feed on the fine root hairs of your plants, causing them to lose vigor and develop yellow leaves. They can also tunnel into the base of cuttings or plant stems, which can be devastating for succulents, leeks, or onion seedlings in particular.

Fungus gnats search out moist soil in which to lay their eggs. The eggs are about 1/100 inch in length and laid in clusters. Larvae are translucent gray to white worms, about 1/4 inch long, with shiny black heads. These insects can infest a crop from wet, algae-covered areas in the garden, from contaminated potting soil or by flying short distances from plant to plant.

The easiest way to prevent fungus gnats is to water your plants properly. Overwatering, which causes your potting mix to remain moist for extended periods of time, attracts fungus gnats which seek out a steady supply of fungi, algae, and decaying plant matter for their larvae to eat.

If you allow the soil to dry out between watering, you can disrupt the availability of food for the fungus gnat, and make your soil less attractive to them.


tomato seedling bent by damping off disease
Darn those tiny lumberjacks!

Not only will controlling your watering help prevent fungus gnats, it will prevent the second most common problem for indoor gardeners: Damping off.

There is nothing more heartbreaking than saying goodnight to a tray full of robust, little seedlings and waking up to find them all knocked down and laying dead on the soil, as if felled by tiny lumberjacks in the night.

This condition is caused by several fungi such as Phtophtora and Pythium. These fungi are often carried by fungus gnats, and live at the soil line, where air meets the moist soil surface.

When your potting soil is kept continuously moist by overwatering, and your seedling roots are weakened by fungus gnat larvae, the damping-off fungi can easily infect your seedlings.

The telltale symptom is a constricted stem, near or below the soil surface. Once seedlings are infected, they tend to fall over dead, and must be replanted. There is no cure for damping off; it can only be prevented.

Potting mixes containing compost or peat moss seem to be particularly affected by fungus gnats and damping off. If the problem is reoccurring for you, think about switching from a peat-based soil mix to one that only contains perlite or vermiculite.

Because fungus gnats have a quick life cycle, it is important to reduce their numbers by using a combination of methods that control them both as adults and as larvae. Whether you choose physical controls and/or biological controls, there are a variety of affordable, safe choices for ridding your indoor garden of pesky fungus gnats and their plant-killing larvae.

Physical Controls

Sand – Controls larvae

Adults lay their eggs in the top 1/4 inch of moist soil. If you dress the top of your soil with a 1/4–1/2 inch of sand, it will drain quickly and often confuse the adults into thinking the soil is dry. You can use colorful decorator sand and have fun with this!

Vinegar – Control adults

A good trap for both fungus gnats, and especially fruit flies, is to put out baby food jars filled halfway with apple cider vinegar or cheap beer with a couple drops of dish soap added to break the surface tension. Once you’ve filled the jars, screw on the lids, and poke several holes into them large enough for fungus gnats to enter.

Place these jars in areas where you are having problems with either fungus gnats or fruit flies, and they will dive into the vinegar and drown. Strain and reuse the vinegar until you have gained control of them.

Potato slices – Controls larvae

Slice raw potatoes into 1-inch by 1-inch by 1/4-inch pieces. Place the slices next to each other on the surface of your potting media to attract fungus gnat larvae. Leave the potato slices in place for at least 4 hours before looking under them. (Be prepared to be grossed out a bit.)

Once you have seen just how bad the problem is, replace the potato slices every day or two to catch and dispose of as many larvae as you can, and consider adding additional control measures.

Sticky Traps – Controls adults very effectively

plants in pots under lights with yellow sticky traps
Note the HORIZONTAL orientation of the trap

Make your own sticky trap by smearing Vaseline or Tanglefoot on a 4″x6″ piece of bright yellow cardstock, and place the card horizontally just above the surface of your potting media, where it will catch the adults as they leap from the soil. Set another trap vertically to catch incoming gnats, whiteflies, thrips, and more.

I often lay these traps on the edges of pots, or make little holders out of old, bent forks to hold them horizontally or vertically, as needed. Where to find pre-made yellow sticky traps and holders online.

Food Grade Diatomaceous Earth – Controls larvae and adults

Food grade diatomaceous earth is highly effective treatment to get rid of fungus gnats. Diatomaceous earth (DE) is mineralized fossil dust that is both natural and non-toxic to the environment. Make sure you get food grade diatomaceous earth—not pool grade, which is not pure enough for use around food gardens and pets.

Always wear a simple dust mask when working with DE: Inhaling any kind of dust is never a good idea.

DE contains microscopic shards of silica that physically shred any insect that walks through them, therefore it will not work in hydroponic gardens. But if you mix some into the top layer of infested soil—or better yet, into your potting mix before planting—it will kill any gnat larvae (and adults) that come in contact with it, as if they were crawling through crushed glass.

DE works the same way to kill fleas, bedbugs, slugs and other insects too, so don’t use DE to control fungus gnats in your compost bins. (Poor worms!) Where to find food grade diatomaceous earth online.

Biological Controls

Hydrogen Peroxide – Controls larvae

Mix one part 3% hydrogen peroxide with four parts water. Allow the top layer of your soil to dry, and then water your plants with this solution as you normally would. The soil will fizz for a few minutes after application; this is normal.

Contact with hydrogen peroxide will kill fungus gnat larvae on contact. After a few minutes the fizzing stops and the peroxide breaks down into harmless oxygen and water molecules. Repeat as needed.

Chamomile Tea – Controls damping off

Weak chamomile tea (after it has cooled) is another natural fungicide that is effective in preventing damping off, though it does not treat fungus gnats at all. Simply brew a quart of strong tea, let it cool, and add it to your 1-gallon watering can. Add more water to the can until full, and use whenever you water.

Cinnamon – Controls larvae and damping off

Cinnamon powder is a natural fungicide that has been shown to be particularly effective against damping off. It helps control fungus gnats by destroying the fungus that the larvae feed on. True Ceylon cinnamon, or Cinnamomum verum, will work best.

Simply sprinkle enough cinnamon to form a thick, visible layer across the top of your potting media, covering it completely, and repeat every few weeks, if needed. DO NOT use cinnamon to control fungus gnats in worm bins as cinnamon will kill your worms. Where to find cinnamon powder online.

BT – Bacillus thuringiensis var. israelensisControls larvae

Bacillus thuringiensis (Bt) is a naturally-occuring bacteria that effectively kills many types of worms, caterpillars, larvae and insects. There are specific strains of Bt called “israelensis” or “H-14” that specifically kill fungus gnat larvae. (Other varieties of Bt will not work for fungus gnats.)

Used extensively in organic greenhouses, Bt-i can work to stop fungus gnats where nothing else will, though it is a little pricey. Bt-i is safe for use in worm bins, and can help control mosquito larvae too. Where to find BT-i online.

Beneficial Nematodes – Controls larvae

There is a type of nematode, Steinernema feltiae, that can be used to drench the soil each time you water. These tiny worm-like creatures will enter the larvae of soil pests like the fungus gnat and release a bacterium which is lethal to it.

Nematodes work well, but they are expensive, and are best used on a large infestation of many plants, because they are hard to control in small quantities. Nematodes kill a variety of soil-borne pests, and are safe for use in worm bins, too. Where to find beneficial nematodes online.


161 thoughts on “How to Control Fungus Gnats and Damping Off Organically”

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  1. Re; treating at all stages; it occurred to me that I might use nematoids for the larvae and DE for the adults, simultaneously.

    But – is DE as hard on nematoids as it is on the gnats?


  2. We have a problem with fungus gnats in the house, no plants around but could they be hatching underneath a sisal carpet?

  3. I’ve tried EVERYTHING to control gnats. I grow in soil (fox farm) in unglazed clay pot, plenty of drainage. Best thing so far… Mix DE in water and drench topsoil. Allow to set, Oh yeah, prior to be sure to remove large particles from soil, screen to 1/4″ . once top soil is dry, cover with medium haydite, i don’t know if deeper is better, I just barely cover topsoil. Of course, infrequently water, most often from bottom trivet. Make ‘drench’ by soaking mosquito dunk, and soap nuts, in jug for at least several days prior to utilization. By all means avoid applying organic fertilizer to haydite. make monitor traps with tanglefoot. Make a uv lamp helps, but I’d rather fly a kite.

    1. Avatar photo
      Jamie Lynn Tushner

      Hi! I thought that DE was only effective in controlling gnats when used in its dry, natural powder form, so to remove the exoskeleton and “shred” the little bugger. Are you saying that brewing it as a tea and using that to drench soil is also effective?
      Thanks I’m advance for any clarification.

  4. I’ve read that it is wise to treat plants next to those infested with fungus gnats. With that being the case, there are five orchids. Do I subject the orchids to the hydrogen peroxide treatment over the roots (to kill any possible larvae) and Nemo oil spray over the top and bottom of leaves? I had noticed the gnats on a couple of the orchids before knowing of their ulterior motive. Treating all of our houseplants has been quite a task. Appreciate any guidance.

  5. I’ve tried the hydrogen peroxide method on established potted plants. 1 to 3 ratio didn’t work so I kept strengthening the mix to finally a 1-1 ratio and even then, all it does is flush the larvae and pupae out.

    My only success to date is a 1 inch layer of DE. After 7 days, the grown adults all come out and slowly die from the DE. I imagine they can’t penetrate it either without dying. A full 2 weeks later, I counted hundreds dead.

    DE is a really fine particle so you have to wear protection, really bad for your lungs. But it kills those pesky gnats!

  6. I have had a problem with fungus gnats for years and have tried several different remedies, including nematodes. Nothing worked until I tried the diluted peroxide method together with diatomaceous earth. It seems like the problem is finally gone, inside of a week. Thanks for posting!

    1. ThnxSo much for letting us know what actually worked for you!
      I am pre sprouting my dahlias and starting seeds and I am infested right now!

  7. Hello Dawn: I am a senior citizen member of my local Horticultural Society in Blind River Ontario. I publish a weekly post on our FaceBook Page. I found your article very, very informative. Kudos to you because I know how long it takes to research a topic before posting it. Mine usually take 8-10 hours.
    I understand why you want to protect your material, but I hope you will give me permission to share it with other members on our FB page.
    Thank you so very much for your article. Sandy Lendrum

    1. There are social media buttons on the post precisely so you can share the link. All I ask is that you not cut and paste the text, rather link the actual URL of the post.

  8. Another thank you for your article. This is definitely my go to resource for fighting the tiny lumberjacks and their air force.

    I didn’t have much success with the vinegar traps, but a small bucket of water with a drop of soap seems pretty effective when placed near the seedlings. As a bonus, it increases the humidity around them too (not much, but every little bit…).

    1. Thank you so much for taking the time to post this article. It was extremely informative. It was appreciated that you put what methods would not or would hurt worms. I don’t have a worm box, but I have some worms in my plant pots. I was looking for a method that would not bring harm to them in the process. I am still new to house plant growing. I have over 20 plants in the house and these gnats have to go, lol. They’re not paying rent but are always in my face,! Lol. I learned a lot from your article! Thanks a million and one!

  9. Avatar photo
    Stan G. Sugnuf

    Just wanted to say that this article is one in a million. Very informative and helped me a lot. Thank you.

  10. I’ve placed sand over my plants as a last resort to battle fungus gnats and it appears to be helping significantly. Now I’m worried – will the sand inhibit my plant growth? I don’t want to accidentally kill my plants or stunt their growth. Any advice you have for me would be wonderful!

  11. I’m so gald I found this site and article. Gnat problem is big, I’m also glad I live in hot south Florida. I did the proxide watering but soil is wet because most of my plants like wet soil. So I took all of the house plants outside and put them in the sunshine. I stired up the top layer of soil and put lite layer of cinnamon on them. So I’ll let them dry out completely and do another proxide watering. Getting potatoes and vinegar today and will do that step. I keep you posted on how things are going? Can’t wait to read the book.. Dawn hope your feeling better I too have a clinical illness.
    Thanks for all the great work you did and for sharing this with me and everyone.
    Joyce S

  12. Gnatrol was my last hope…but it is a sterilized medium, so it was not a long term solution. Actually was worthless, the gnats loved it. My plants started wilting from overwatering with gnatrol. Finally found some food/garden grade diatomaceous earth, or silicon dioxide. Mixed in about 8 heaping teaspoons into the top 2 inches of my 2 5 gallon pots. Had given up all hope really, gnats totally out of control….fungus gnats gone overnight…worth the trip to Lowes. now I can keep my plants alive all winter in my bathroom greenhouse!!!

  13. Many thanks. I use big yellow sticky traps which capture yuck, loads of these pests but noticed my bag of potting soil was a source of the gnats I couldn’t quite keep up with until I tried the hydrogen peroxide. Yay! Problem solved.

  14. Two years ago I had a compost gnat problem in my house, easily solved as the plants were destined to go outside. This year I again have the gnats indoors — but the plants are to stay inside. To prevent the gnats, I started watering from the bottom; got the gnats anyway. Put yellow, vaseline-covered strips on top of the soil — caught no gnats. Bought sand and topped the soil with about 1 1/4″ of it (still watering from the bottom; gnats increased. Covered the tops of the plant containers with plastic cling material — and I still have gnats, although marginally fewer. I just found out about hydrogen peroxide and might use that next, and/or BTi, but I’m concerned the gnats can breed in other places. These are not fruit flies. They are definitely compost gnats.

  15. Hi Dawn I tried the Hydrogen Peroxide, The BT,letting the soil dry out,sticky traps and non of these worked still infested with those dreadful fungus knats. I am about at my wits end any suggestions?

    1. Oh dear! It might be that you have a vector in your house that is reinfesting the plants, such as a drain pipe or another infested plant. Since I’m not in your home, it’s hard to say. If the plant is really valuable to you, you might need to just keep their numbers small and manageable by consistently using sticky traps and monthly hydrogen peroxide or nematode soaks. Sometimes it takes several life cycles to get them under control.

        1. You can try it, but I think you will find it is not foolproof, and the gnats will enter from the bottom.

        2. Hi.

          Can I use hydrogen peroxide on my pots with veggie seedlings more than once a week? If I water the plants twice a week, can I use HP twice).

    1. Hydrogen peroxide only kills them at the larval stage of their life cycle. You will need to use methods that catch them at all stages.

      1. Thank you so much for the wonderful post! Just wondering after I apply DE for a couple weeks, do I have to remove it? Or just leave it on top of the soil? And also is pouring HP bad for my tomato plants? Will I still be able to eat the tomatoes after the HP treatment? I plan to use both DE and HP.

        1. Neither are harmful to leave on your plants. HP works best in indoor pots though, not out in the garden. Enjoy your tomatoes!

  16. Avatar photo
    Catherine Luter

    WOW!! This segment answered every single question I had and some I hadn’t even thought of asking but needed answered. You’re a veritable fount of information, hon!! To stay stay within the metaphor…my cup runneth over!!! Thank you so much! 🙂

  17. Great article! Very informative.
    I researched the properties of ceylon cinnamon vs. cassia…
    To say that only ceylon cinnamon will work to control fungi and deter fungus gnats is incorrect. Rather, cassia contains much, much more cinnamaldehyde, the anti-fungal chemical- saigon, being the most potent. But, Ceylon is the best for dietary purposes, because it contains very low amounts of coumarin, a blood thinner… Happy gardening!

  18. I tried your potato method without attracting any larvae.. I am using coco coir as a growing media. I know for sure I have fungus gnats so wondering if I there’s any other details I missed? Could it take longer than 4 hours? Do I need a bug scope to see the larvae? Thanks!

    1. I would definitely leave the potatoes for a few days, not a few hours. Also you will want to use more than one control because potatoes only work at one stage of their life cycle.

  19. Hello Dawn,
    Quick question that may see silly, but what is the best way to get rid of the larvae on the potato slices if they are there when I check in a few hours? The reason I am asking is because I don’t want to put them in the trash and then they still hatch in there, or outside in my trash where they can possibly hatch before pick up and somehow crawl out of the bag… just unsure if I should spray them to kill, flush down the garbage disposal or toilet? New to gardening this past Spring – and very green in my attempts and experience.

    Thank your for this information as I have tried several things to no avail and have begun implementing a few additional ones this week in an attempt to get rid of all fungus gnats. Driving me crazy! But I don’t want to remove all of my wonderful herbs and lettuces – some of which have struggled I feel certain because of the gnats.


    1. Remove them from the house in a manner that won’t allow them to escape back to your houseplants. In your outside trashcan should be sufficient.

  20. Hi everyone!
    I tried removing fruit flies by making fruit fly traps and pouring vinegar and baking soda down the drains a couple of times, but they keep coming back. I read on that it might be because the flies have laid eggs in the drains and that pouring boiling water down the kitchen drains every day will completely remove the remaining fruit flies eggs, so I thought I’d ask your opinion on this since it seems like a “too simple” solution. I also read that I can make farmers trap with milk, sugar, ground pepper and soap, so I’d like to hear what you think of these and if they would work.

  21. Hi!
    Thanks so much for the advice. I had the brilliant idea saving some money by going down to the park, where they were doing some construction,and getting some free soil, I asked the construction foreman and he said there may be pests present in the soil, as always(when trying new things) I thought I was smarter than everyone around me, (I usually find out the hard way that’s not true.?) I thought “I’ll just microwave or bake the soil and it’ll be fine.” Fungus gnats must have super powers or maybe I didn’t cook it long enough or hot enough, because about a week later I started to notice “mini” anorexic looking mosquitoes that didn’t bite,flying around my kitchen. Then my plants begin to droop, I’m going to try the hydrogen peroxide method and let you know how it works out.
    Thank you Sincerely,
    Penny, Kitchener Ontario Canada.
    (Still got to learn advice is usually given from the advisors having first-hand experience)?

    1. Hi Penny,

      Unless you did a lot of amending to the soil(?) from the park, even a potted shrub would not survive. Soil needs to be porous. There need to many micro pockets, where air can get to the root. When you water or it rains, the water is able to move easily through porous soil, bring with it trapped air bubbles. A plant’s roots need need oxygen to survive. Compacted soil holds water, but not any air without air the plants roots start to rot. If the park was a grass covered, the soil will be even more compacted and contain very little nutritional value.

      I’m not sure the plants you are growing, but a typical plant will require you amend that soil with perlite and one or more porous materials. Peat, Coconut Coir, Bark mulch, pumice, other lava rocks, etc… each make the soil more porous along with other qualities. You will also need to add some compost to give the soil some nutritional value. The compost makes the soil heavy, so more porous material will need to be added.

      In the end you spent more making the park soil usable. When you could have bought a bag of organic container soil or seed starting soil. I write organic, because the park soil has unknown levels of pesticides.

  22. Hi, Thanks for the wonderful information. I tried one of your expirrment and really benefitted. Whatever you write and think is extremely scientific thus helpful . I am really lucky to find your website. Thanks
    I am from India (extreme climate)
    Please reply one important question.
    I have a net green house in which I have ORCHIDS only , I need to keep 60 to 80 % humidity please suggest the best method to remove molds ,fungus etc from my green house as i cant keep my green house dry for a longer time. please help..

  23. I have a serious problem of fungus gnants in my orchids!! I just finished watering all of them (22) with the diluted peroxide. I have gotten rid of a lot of adults but with sticky tape but when I watered today I saw a lot of little ones (must have just hatched) swimming around in the water. How do I get rid of them? Also how often should I water with the peroxide mix? I’m not sure if I can try any other tips since the orchids are in pots with holes on the sides for drainage. I really need to get rid of them fast. Thanks for any help you can give me.

    1. I’m so glad I found this article. I am having a problem with fungus gnat in some terrariums I have made. Terrariums are naturally moist and humid, so this is like heaven for the Gnats. I was trying to source Gnatrol but couldn’t find it in Australia. The BTI is only available in Mosquito dunks but I’m not sure if it will work. So, I am currently drenching the soil with Eco-Neem, hopefully I have some success, although I am not sure for how long I am suppose to do this or if I need to repeat the application. I would like to try DE but I wasn’t sure if it would be effective wet? If, so I milght build it in to a layer of my terrariums. Any ideas?

    1. I’m not certain but hydrogen peroxide is probably not great for worms. You could try a test batch and let us know!

      1. Doesn’t affect worms. But it (hydrogen peroxide <1%) definitely doesn’t kill fungus gnat larve on contact. 30% Alcohol will, but don’t water your plants with that! I’ll remove trouble soil and spray a bit if i see lots of larvae.

  24. Thank you for this information about fungus gnats. I was wondering what had gotten to some of my plants and why these little gnats were harder to get rid of than fruit flies. I feel certain your suggestions will help solve this problem. Also, do you think these little invaders have come with bananas? Awhile ago, I noticed a fruit fly problem after leaving bananas on my counter top instead of my usual practice of freezing them immediately.

  25. Hello Small Foot Print Family, Thank you so much for the wealth of information on fungus gnats. I began treating the outbreak in my house with the hydrogen peroxide and the yellow sticky fly paper. I also tried the potatoes. One word of caution with this method: The adult flies were using the moist potatoes to lay their eggs on. Yikes! The outbreak re-surged. Today, I applied DE (food grade) to all of my existing indoor plants. I had already applied it to my seedling pots. I have begun sharing your website with my other gardening friends. It’s wonderful!

  26. Hi, thank you for all of these ideas. Right now I’m trying the trap paper, potato slices, and an apple cider vinegar trap on each side of the pot. I’m a first-time grower so I had no clue that plants could still get infested with pests indoors! Please let me know if the hydrogen peroxide remedy is safe for young seedlings.

  27. I have a small gnat problem in which I use a vacuum cleaner to suck up the adults. I just tap the bins and agitate the top soil to get the buggers flying and bam. I do this 5 or 6 times a day and any other time I have to water or whatever. Seems to work. I am also using D. earth as well.

  28. Thank you so much. So fur the best informative put togather article on the web i could find. You awesome. Thank you for sharing intensive research. It takes time!

  29. I saw mosquito dunks in Home Depot / Lowes. Are they same as gantrol or knock-out-gnats? The packages says BTI which sounds like the same strain of bacteria. Has anybody used them?

    1. I wondered about this too. I can’t find BTI in any other form (In Australia) than in Mosquito dunks. I”m thinking of giving it a try.

  30. My seng tui money tree has had stunted growth because of the blighters! I’m using cinnamon and the drying tenchnique, so hopefully it’ll work

  31. I’m so glad I found this! I introduced a plant to my indoor garden recently I think was infected with fungus gnats, and now the gnats and the fungus they carry are destroying my herbs 🙁 I’ve already tried the diatomaceous earth, have a fan blowing on my plants, and sticky traps for daaaaays but they are becoming more numerous by the minute. Just tried the hydrogen peroxide trick, and will be investing in those nematodes and such. Losing my mind seeing my cute little baby tomato plants and herbs get ravaged by these mofos and the fungus they spread!

  32. I do in house pest control and we are have Fungus Gnats in one part of the facility. It about 4 stories above the ground, and it is a very wet and damp area. There are sugar and food particles everywhere. I catch the FG in insect light traps with glue boards in them. I can’t seem to find the source, I’ve spent hours looking for where they are coming from and the light traps aren’t controlling them either. Any suggestions? It is a food facility so we are very limited in what we can try. Thanks for any help you might have.

    1. They really could be coming from any damp or moist areas. They especially like to live in drains. Anything you can do to mitigate the moisture in the area will help your other efforts, as will closing up the drains with stoppers until you need to use them. Good luck!

  33. Does anyone know if DE (diatomaceous earth) still works once it gets wet? I would guess it does, otherwise how could one water their plants? Anyone know?

    1. Several sources state that DE is less effective when wet, because it tends to clump together. To get around that, try using a watering bulb inserted near the root of the plant instead of freely watering the surface. Or, try using a “plant spa” style pot, that is meant to be watered by pouring water into a tray under the pot, then the water soaks into the lower layers of soil where the plant roots can find it. (Note that such pots only work for deep rooting plants and do not work if you fill with layers of rock under the soil.)

  34. I am specifically looking for a solution to fungus gnat infestation in my indoor container vegetable/herb garden. I purchased knock out gnats and now I have to throw away all my plants because I wasn’t suppose to use it on edible plants.

    1. There are many solutions in the post that should help. If your food is a fruiting crop, like tomatoes, you shouldn’t need to throw it out. You just don’t want to eat lettuce, for example, that you have poured Bt onto. Always apply any solutions to the soil, and not the foliage of your plants.

  35. There seems to be conflicting advice out there on whether Ceylon Cinnamon or Cassia Cinnamon is the better fungicide. This website says that only Ceylon will work. But other sites, including this scientific study, appear to suggest that coumarin is the more effective fungicide and Cassia has more coumarin in it than Ceylon, suggesting that Cassia is the better fungus inhibitor and killer. Would love to know more if you have more literature on this and or can point us in the right direction.

    1. Thanks for sharing a study that shows both can work. I think this information will matter most if you have a commercial scale operation that depends on regular control. For the home gardener who just wants to save a few houseplants or seedlings, I recommend whatever is in the cabinet or easily available at the store. In practical terms alone, that will work best and fastest. If you can get Ceylon, I find that that works best in my home.

  36. Just a quick correction, DE (Diatomaceous Earth) only impacts insects with an exoskeleton. Worms don’t have exoskeletons so it actually will NOT harm them.

    1. Food-grade DE will not harm earthworms, but pool-grade DE can be harmful to them. DE can also kill slugs and snails, and food-grade DE, when ingested, can kill intestinal worms and parasites.

  37. Thanks everyone! I have a beautiful indoor garden here in Korea– about the only way to get chives, basil, cilantro. I also have some tomatoes and strawberries and flowers. I lost some young spinach and greens and young basil to the little buggers, but after almost a week of drying out my soil and a day of cinnamon and peroxide washes, the bugs are gone and the plants seem OK. I hate to kill anything, but these things just don’t deserve mercy. This site (and others) have been so helpful! It’s not possible to get the recommended pesticides here (organic pesticides worked OK on the adults– but I’d used them for weeks and the larvae continued). Peroxide and cinnamon are slightly more expensive here– but well worth it as my garden is organic and I love it.

    1. I’ve had two of my pepper seedlings dampen off .. And my herbs have seen brighter days. Will straight peroxide harm my tomato seedlings? At this point..I just wanna get rid of these buggers. My last remaining pepper seedling has barely breached the surface..hasn’t even stood up yet. Do I spray the peroxide all over? Or lightly pour it around the outside? Newbie here…thanks.

      1. To stop damping off, you’ll want to use cool chamomile tea, which will not harm your plants. Straight peroxide might be strong for tiny seedlings, so you might want to plant a lot of them so you have enough to cover some losses, or try something a little less harsh on tiny plants, like diatomaceous earth.

  38. I used cinnamon for some of the potted plants and they seem to work, but I sprinkled some on my seed pods in my aero garden and some of the already sprouted seeds didn’t like it too well. My mint immediately wilted, my Curley parsley wilted. And so did some of my basils. The chives didn’t come up yet at all so I don’t know how it effects that. The tomatoes seem to be doing just fine.

  39. I had a really bad fungus gnat problem in one of my bigger pots. I tried an organic fungicide (Garden Safe), but it didn’t help at all. Used the yellow sticky traps, and they worked to get the adults, but there must have been so many eggs that I couldn’t keep up. I finally put a layer of diatomaceous earth on all the soil and that solved the problem immediately. I’m leaving it there for at least another three weeks to make sure I got all the stages of the gnats. I will have to water carefully and reapply in the meantime, but it will be worth it. I definitely recommend trying the DE if you need a quick solution!

    1. I’ve always had houseplants. Until last year I’ve never had gnats and I’m in my sixty’s, so I’m wondering why I’m getting them now or maybe why I’ve never had them before. Anyway these bugs are driving me crazy, I thought I was losing my green thumbs when my clippings of plants would do great in water and root like always and they would start to grow in the soil then overnight it seems they die. Until tonight reading this information I realized it’s the gnats that are killing them. So everyone got a peroxide watering. But I have to do something with the adults.I don’t have any yellow index cards so I need to know if it has to be yellow or will white index cards work? I getting the potatoes ready to try. I’m so glad your website showed up this time when I ask Google how to get rid of gnats. The information on this site is the best I’ve ever seen. Thank you! My question is does it have to be yellow paper?
      Joyce S

      1. Bright yellow is much more effective at attracting flying insects like fungus gnats, but white will do in a pinch.

  40. This is one of the most thoroughly detailed, informative pieces I’ve ever read on fungus gnats! Very nice page design, as well.

    Thanks for the great information! Definitely bookmarking your site.

  41. Would hydrogen peroxide be harmful to succulent roots? They’re just so sensitive compared to other plants I’ve taken care of. Others here have mentioned treating with straight undiluted 3% hydrogen peroxide; have any of you tried the undiluted stuff on succulents?

    1. I’ve not tried it on succulents personally (maybe someone else will chime in here), but you might want to test it out on one before you apply to your whole garden.

      1. I used 3 parts water to 1 part HP on all of my plants succulents and otherwise. Everything seems to be all right. My Aloe Vera has some browning on the leaf tips, but it is still generating new growth. I could not say if that is from the FG or the HP.

    2. Hydrogen peroxide burnt the leaves of my Peace Lily.
      I have a Gnat problem now with my Happy Plant and want to avoid burning the leaves so tried the cinnamon remedy suggested and hasn’t helped. Going to my local gardening shop to ask for a Gnat control mix.

      1. Peace Lily’s are surprisingly sensitive to minerals and chemicals, like prayer plants, this includes fertilizer. I water mine with filtered water and rarely fertilize. I also flush water every so often, where I add the filtered water (non tap water) while keeping my thumb on the drainage hole so that the water accumulates up to the top soil and hold it there for a few minutes and jiggle the pot slightly until I no longer see air pockets, and then I let it drain. Once drained I water as normal. This will help flush out whatever minerals or chemicals might be bothering it.

  42. Your article on gnats is great! Thanks so much! Would DE made from Safer brand be adequate to apply as a top dress, or is there another brand that works better? Also, Gnatix (brand name) is crushed glass that I’ve been told works amazingly well. Ever try that?

    1. Any brand of DE could be helpful, however I would avoid using crushed glass around pets, children or plants/seedlings I intended to transplant.

  43. Wow! I can not thank you enough for this info!! These little pests seem to LOVE my succulents and i don’t use any pesticides on my plants. This is the first useful info i have come across in my search for a cure, THANKS A MILLION!
    *also thanks for the idea (your 4yr olds personal corner)i have a 3yr old helper who LOVES to garden with his mommy, only he thinks my succulents and cacti area ALWAYS thirsty. “She was thirsty mama, she needed drink,Eli take care of her mama”somehow I’m always too late to stop it 😉

  44. I’ve been trying some of these. The potatoes only made the little flies copulate… They seemed to have found it cheekier than the soil itself.
    I have now made my own sticky traps -vaseline over yellow post-its- and although it was fun making those little handsome bastards, little flies don’t seem lured by it… Think the potatoes might have filled that void inside their funky little being.
    Could mine be a slightly different type of gnats? Maybe a “you won’t fool me” type?

    1. You’ll want to remove the potatoes frequently, if not daily, to get them to work. Also make sure your sticky traps are BRIGHT yellow. I will often shake the pot or stir up the soil a bit to get them to jump. They get stuck on the traps much more quickly that way. If you have a huge infestation, you’ll want to use nematodes as the most effective method.

      1. Do nematodes also kill off all the beneficial healthy bacteria in soil/homemade compost?
        Thanks everyone for Making this article even better w personal experiences in comments!

  45. I have a bunch of potted plants and all are infected. I tried the diluted version of peroxide 3% and water and it had no effect. Out of desperation I poured straight peroxide right onto one of my plants and it seems to have done the trick. Seems like a zillion gnats came flying out of the plant and flew off. The soil bubbled up then settled back down. The plant doesn’t seem any the worse for it either. It is over a week now and I haven’t seen a gnat on that plant since, nor do I see any larva in the soil. Now I will do all the rest of my plants too. Thanks for the tip.

    1. This is what I have always done- straight hydrogen peroxide- and it cures it pretty quickly! No harm to the plants either. For the little spiders with cottony webs I spray slightly diluted rubbing alcohol on my plants and soil and that takes care of those too. Great information in this post!

  46. The good news for those of us finding out just now that we’ve been lied to for years about our cinnamon is that for the purposes of killing fungus and therefore fungus gnat larvae, cassia (cinnamomum cassia) is just as antifungal and antiviral as is ceylon (cinnamomum verum). The cinnamon you have on your shelf, even though it’s probably not true cinnamon, will be just as effective. Cassia is still a hot spice and contains hot oils, and it’s not the same species of plant but it is from the same genus.

    1. I was just about to respond to this article with the same info about cassia. People for some reason forget it’s from the same genus and contains the same antifungal properties.. one of the main components being cinameldehyde. The main difference between the two is just how much more Coumarin is in cassia but that doesn’t change the benefits. Thanks for pointing it all out! ???

  47. Thanks for all the help. I have some house plants, including herbs (I’m in an apartment) and the fungus gnats are back. So I was thinking that I should try the hydrogen peroxide solution first. If that does work, then I’ll get some DE. How does this sound? Will either hurt my herbs (dill, rosemary, basil and lavender)? How many treatments with the peroxide solution should I do before determining if it’s done the trick?

    1. 2-3 times should do the trick, unless you have a massive infestation. It shouldn’t hurt your herbs, but if you are worried, use a more dilute solution.

  48. I have a drainage ditch field next door to my house where noseeums gnats and other insects are very prevalent . I have tried almost everything but nothing seems to work. Is there any way to break this cycle around my deck area so this kids and family can enjoy our outdoors? We also have a very large garden which doesn’t seems to mind All the flies gnats and noseeums….

    1. Unless you can get rid of any standing water, moist soil and organic matter in the ditch, there won’t be much you can do. That ditch is a little ecosystem. You can install citronella or essential oil torches around your deck to get at least some relief.

    2. This will do the trick and not contaminate the ecosystem in place in that there ditch!
      Microbe-Lift® BMC kills developing mosquitoes before they become breeding, biting adults. It is a liquid product, so it has no adverse effect on the aesthetics of ponds and water features. Microbe-Lift® BMC can be applied to areas that can contain aquatic life, fish and plants. It can also be applied to areas used by or in contact with humans, animals, horses, livestock, pets, birds or wildlife. 2 oz treats 400 gallons for 2 years. 6 oz treats 2,000 gallons for 16 months.

  49. Hello and thanks for the post. I have a nasty infestation of fungus gnats. I don’t water much (twice a week in Northern Cali) but my plants are all potted. PB started after I muched with cocoa shells and worsened with added dry blood to the soil.
    I’ve tried nematodes and Stratiolaelaps scimitus (=Hypoaspis miles)
    SKU: 1154002-G (twice and the second time they sent me 4 times the dose by mistake… used it all!). So far no success. Can I use chamomille and/or cinammon or will I kill the nematodes and beneficial mites ? How about Bacteria thuringiensis var. israelensis ?
    Should I not much this year ? What do you think about blood ? My plants love it (until the gnats hurt them!)

    1. Avatar photo
      Dawn Gifford

      Anything that keeps the soil from drying out can encourage fungus gnats. However Bt can help and other beneficials can help.

  50. Thank you SO much! I lost so many seedlings last year due to dampening off – I had no idea what was wrong with them and it was so discouraging. Now I know!

  51. I have a question, I am growing wheatgrass, and I can’t tell if what I have are fruit flies and/or gnats, I am not a usual grower, anyhow, what can I spray on my wheatgrass if anything that will repel the gnats/fruit flies, and what is the best thing I can add to the soil now, and before I add seed to the soil?

    Also the grass looks good, and is almost fully grown, can I still eat the greass even though those things have been on them? Sorry for all the questions, I haven’t found the answers I have been looking for so maybe you can help. Great artical btw, I am bookmarking this page!


    1. The only ways to be rid of fungus gnats are using the methods in the post, and there are several ideas for you to try before your next planting. There really is nothing you can spray though, and it would ruin the wheatgrass anyway. The gnats won’t hurt the quality of your grass if it has already grown in well, so don’t worry about juicing it. 🙂

      1. can i use cinnamon on my wheat grass soil – if so when do i put it on right away when i plant the sprouts? will it harm the wheat grass – I would think not?

  52. God Bless you for sharing this info. THis has been the bane of every attempt ive been making at growing indoor herbs, seedlings etc. So helpful to find all these remedies in one place onece again ty.

    1. How much of what? Cinnamon, nematodes, diatomaceous earth? Generally, you need only apply cinnamon or DE to the surface, where the gnats live and breed. How much will depend on your pot width and infestation level. I would surely cover the top of the soil.

  53. Thank you for the best info so far!
    I am starting an urban container garden this year, and I have 6 large pots and a balcony to work with. I have seedlings starting indoors. I bought 6 bags of Organic Miracle Grow veggie soil, and soon I will pot and set everything out on the balcony.
    I did some research on the fabulous new soil that I purchased, (the organic miracle grow) and it seems that almost 90% of the people who bought this soil reported a severe gnat infestation from larvae that is mixed in the soil.
    If I do have gnats in the soil once I open it, what would be my options? This is a situation where I wouldn’t have them on the surface alone, but mixed in the entire thing. What would work best?
    Thank You

    1. Getting some Bt is probably your best bet if the soil is pre-infested, as well as using proper drainage and watering techniques. If the soil isn’t pre-infested, treat using any of the remedies in the post! Good luck!

    2. Hi Alina; I am one of the 90% who have pre-infested bags of Miracle Grow sils (not so nice a surprise last weekend when I opened the bags!). Were you able to kill them all off in the bag? If so, what worked for you. I’m at a standstill nright now – I think my gnats like dry conditions as well as wet!!! :(. Thanks.

    3. I have read many posts where you lay a layer of soil on a baking sheet or two and bike them in the oven for 30min under 350 degrees. That will sanitize the soil and kill any larvae.

    4. I use Miracle Gro and had gnat problems…I see that other soils encounter the same problem…I sterilize my soil (soil is heated to 160-180F) for my indoor plants…This will kill the eggs, larvae and pythium fungus…I also use gnatnix on the top of the soil with monitor cards…I live on a shore of a lake so I must stay vigilant…

  54. I have been battleing those darn fungus gnats for a week now! I have tried everything, I am on the potato slices and the cinn. Now with the cinn. is it okay to use organic cinn. sticks? I would think so. I dont know what to do I did stop my oregano from diein, but my pumpkin and squash seedlings are now there wilted. I have been puttin a fan on them during the day to help circulate the air. I also have a grow light on. The sticky traps that I do just keep feeding the flies rather then trap them.

  55. Thank you for this! This has been the best I’ve found in dealing with fungus gnats and fungi. I have a question re cinnamon though. You mentioned that only Ceylon Cinnamon works, but don’t both Ceylon and Cassia Cinnamon contain cinnamaldehyde which kills fungi? I’m concerned because I bought two bags of ground cinnamon, pretty sure they’re cassia.

    1. Cinnamaldehyde is present in both types of cinnamon and it kills fungi in your soil, however cassia tends to attract ants. Anecdotally, many gardeners report that Ceylon cinnamon seems to work better too. But don’t despair; give your cinnamon a try and see how it works!

  56. The best article I found online for how to naturally deal with soil gnats. Thank you thank you thank you! I’ve tried three different methods and am positive that the little buggers ought to stop flying into my nose soon. 🙂

    1. Glad to have helped! You need to catch them at each stage of their lifecycle and keep at it, since they reproduce so quickly. A combination of tactics works best! Good luck!

  57. I have a small potted highbrush blueberry plant and the soil is full of these worms and every now and then the flies are in the soil and on top of it. Also I believe they are in a potted Mint plant as well, but in the mint plant I have also found something similar to the worms but about 3 times as big around but the same length. Not maggots, so what could they be? Ugh, what a pain all these disgusting little creatures are. Thank you for this page & information collected, I hope to try out a few of these ideas & hope it will do the trick. Thank you thank you.

    Medford, Oregon

    1. It’s really hard to say without seeing them, but it sounds like fungus gnats, especially if the larvae are only about 1/8-inch long or less. A good Bt soak (mentioned in the article) could help with both plants however.

  58. Thank you so much for your detailed information, which explains fungus gnat control better than any other site I’ve found. I have a question about using Bt in my 2-tray stacked worm bins. Many worm bin sites recommend Bt, but they don’t explain its use in enough detail. I used Gnatrol (3 t. per gallon) and soaked both levels very thoroughly, then let the excess solution drain off. I have read that Bt should be applied a second time 4 days after the first application, but this will no doubt make my worm bin bedding very soggy (even with draining). Do you if this is the way worm bins are typically treated with Bt? I don’t want to risk drowning the worms. Having multi-level bins is tricky because the gnats have so many entry points. Thank you.

    1. Fungus gnats are composting organisms, so it is very natural to find them in a compost bin of any type. Their presence there is more of a nuisance than anything harmful. Since fungus gnats prefer to lay their eggs in the top half inch of moist soil/compost, you should completely cover the compost at the top of your trays with a few sheets of moist newspaper to create a barrier to the adults who want to lay eggs in the compost. Consider soaking the newspaper in BT before placing it. That way you don’t make your bins too wet for the worms, but you still get the BT on the surface of the soil. Be sure to also use yellow sticky traps simultaneously to catch adults at the top. Good luck! Getting fungus gnats out of worm bins can be very tough since it is a natural habitat for them.

    2. Works wonders on fungus gnats!!
      Microbe-Lift® BMC kills developing mosquitoes before they become breeding, biting adults. It is a liquid product, so it has no adverse effect on the aesthetics of ponds and water features. Microbe-Lift® BMC can be applied to areas that can contain aquatic life, fish and plants. It can also be applied to areas used by or in contact with humans, animals, horses, livestock, pets, birds or wildlife. 2 oz treats 400 gallons for 2 years. 6 oz treats 2,000 gallons for 16 months.

  59. Hi Dawn,
    I love love love your blog and I have a question for you. Will diatomaceous earth get rid of millipedes in a house plant or is there another natural solution that you know of? I am about to dump a beautiful dracaena because of them.

    Thank you so much!

    1. Avatar photo
      Dawn Gifford

      Thanks so much! DE should work well to help eliminate millipedes. They prefer cool, moist areas with decaying plant matter in them, so eliminating those areas from around your home will help too. Millipedes cause no harm, but they are a nuisance, and they smell when they squish or die, so if you can remove the plant to a warm dry area outside for a few days, and pull any mulch or other decaying plant matter away from your house, they may just go away without much hassle.

  60. Avatar photo
    Rebecca @ Natural Mothers Network

    I am so impressed, this has to be the most comprehensive article I’ve read on any one plant pest- a wealth of information and an excellent resource. Thank you so much for sharing this with us on Seasonal Celebration. have a great weekend! Rebecca @ Natural Mothers Network x

  61. Fantastic article! Thanks a lot, will definately be taking your advice just what we need for our little seedlings!

  62. Avatar photo
    Anna @ Feminine Adventures

    Fascinating! I’ve got two little garden helpers this year and am afraid we’ve overwatered several times because it’s just “so fun!” I’d already cut back, but thanks for the additional push to do so!

    1. I keep a designated area of the garden just for my 4-year old’s “experiments.” She is free to water there as much as she would like. It has become really more of a place to make mud pies than grow anything, but she’s happy, and the garden isn’t overwatered!

      1. Hi Dawn,
        Thank you for this informative article. I was wondering if it really matters whether or not the DE is food grade or not? Will it work just as effectively if it isnt? I have all my plants out of reach of my dog and son, because he loves to tear leaves off the plants, so he wouldn’t be at risk of coming into contact with it and neither would my dog. I’m in Australia and have found a website to buy it from, it’s regular grade and this is the description: “Regular grade is ideal to use in your garden (mixed in with garden soil), with fruit trees, with pets and livestock. It is milled to a maximum particle size of approximately 2.00 mm and so is a mixture of powder and larger ‘crunchy’ particles. It is not recommend for human consumption however it is food safe.” And have seen several reviews of people using it on their animals coats for lice protection and letting them consume it for intestinal worms etc. Hope to hear back, just need to know whether you think it not being food grade would make it less effective.. thanks!



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