Gnats in Potting Soil
Suddenly have an insect infestation after using potting soils? Tiny little gnats flying out of the soil in pots and your garden? Yeah, me too. I found out that they’re called fungus gnats, and they are certainly annoying!
I was so ecstatic to have put together my first raised bed for a vegetable garden. It’s nearly full with mushroom compost received from a neighbor, who got a huge haul at a local mushroom farm. The final touch was to add some garden soil to the top of the bed and plant some seeds.
Tiny Fungus Gnats in New Potting Soil
A special sale at a major home improvement store meant that organic soil was just $5 a bag – a pretty good deal. I got two and immediately added it to my bed.
(While this is my experience with this brand, I also tried another organic brand of potting soil and had the same fungus gnat problem. And plenty other people – see the many comments below – have also had issues with other brands, too.)
The next day, I went out to check on my raised bed and noticed the soil teeming with tiny little flies with white wings.
These insects were NOT in the compost before I added I the soil, yet appeared in droves within 24 hours of dumping the bag of soil into my raised bed.
I checked the mound of mushroom compost that I still had in another garden bed that was delivered the same day. Nope, the insects weren’t in there.
I asked my neighbor if he had any problems with the tiny flies in his piles of compost. It was the same compost from the same delivery. That was a negative, too.
So I determined that the organic soil that I bought to complete my vegetable garden actually caused a HUGE problem that now I have to deal with.
Potting Soil Killing Plants
I bought the conventional kind of soil from the same brand last year. I had three healthy houseplants that I had bought from the store and kept in pots for a few weeks that were fine.
When I decided to finally repot them I bought one bag of soil. All three plants were planted in this same soil, and then placed indoors and outdoors in different locations.
ALL of the plants started developing problems and were infested with gnats.
I lost $30 of plants, tons of time in taking care of them, and time spent to return the stuff to Home Depot where the cashier looked at me dubiously as to how my soil could have caused this.
Problems with Fungus Gnats and Potting Soil
Now, fast forward another year, and I’m researching gnat insect infestations online and finding out that this is a very common problem with bagged soils.
This is such an issue that the first comment for these gnat bait traps on Amazon speaks directly about using the baits to kill gnats on houseplants brought in due to bagged potting soil.
Apparently these will work, but I haven’t tried them out.
How to Kill Fungus Gnats
Responses to fungus gnat infestation complaints generally say that the gnats are not a problem to humans. And they cause little damage to plants.
The University of California Integrated Pest Management says differently. They state that a large infestation can kill seedlings or young plants.
The company’s response is also that adding ½ inch or more of sand to the top of your pots will help control the fungus gnats.
Which is good news for those of you who were wanting the look of houseplants planted at the beach or love the feel of the Sahara desert in your garden bed.
P.S. If you don’t mind the look of sand or rocks on your houseplants, here’s a recipe for how to get rid of fungus gnats using sand.
Also great for those of you who want to spend more money on unnecessary products when all you really wanted was a simple bag of potting soil and to be done.
But hey, now you get to go back to a garden center and buy sand and plant sprays and plant amendments. YAY!!!!!!
I had tried soaking my garden bed with insecticidal soap, which apparently doesn’t work on killing fungus gnats.
Adding sand to my garden beds was not an option for me. I was not going to buy a bag of sand, nor did I want to mess with this issue any more.
I basically just lost the entire garden bed and never went back to try again.
Related Posts:
Potting Plants in Compost
After this experience, I don’t buy potting soil at all anymore.
I use straight mushroom compost to pot my plants. I buy mine at Lowe’s, where the price is comparable to a bag of potting soil.
Everyone says never to plant your plants directly in compost. Maybe that’s for rich compost straight from the backyard. Or only cow compost. I don’t know.
But what I do know is that I’ve never had problems planting any plant in mushroom compost or worm casings. It costs a little more, but I don’t have to buy soil amendments, fertilizers, insect sprays from bringing in gnats in potting soil, etc.
If you don’t want to avoid potting soil and use compost, then I suggest you don’t try to pinch pennies like I was. Go to your local garden center and get your potting soil from them.
How I wish I had read this post before I got really excited about planting my decade old indoor curry plant in Miracle gro organic soil which I purchased from Costco? Now after puzzling over a swarm of gnats in the soil for a couple of days and wondering about how that happened I came upon this post. I have to now repot this large plant once again and keep my fingers crossed hoping it survives. I’m going to be heartbroken if this plant dies, a plant which has been a crowning glory of my collection of indoor plants.
Anjana, Oh, no! I’m so sorry! I’m glad you found this post, though, and are able to repot as quickly as possible. Hoping you have success!!!
Same thing happened here! I grow wheatgrass for my cats and was storing the soil under my sink. One day I opened up the cabinet and a swarm of gnats flew up at my face. It was disgusting! I’m SO glad I found this article, because I wasn’t sure where they came from and probably would have bought Miracle Grow again. I thought they were a reputable brand.
Jessica,
I know, it’s infuriating, right?!? So upsetting to spend money on soil and have brought more problems into your home. I’ve also found the soil must be used up immediately, regardless of what brand, because bugs do start to breed over time in any bagged soil, even compost.
OMG YES! Wheatgrass is the worst one I think, not the grass, but using Miracle Grow to plant it in. I am still working on a few left over gnats. Ammonia down your drains at night is also a great way to get rid of a LOT of gnats, it only takes maybe 1/8 1/4 cup in each drain, lemon scented is the best. My problem started when I grew a lot of wheatgrass for my cats, and I have always used Miracle Grow and until recently never had this problem! I have two large bags I’m trying to figure out how to sterilize so I can mix it up for cactus soil. I know you can do it in the freezer, but I don’t have enough room. It can also be done in the oven, thats what I’m looking for!
I just bought Miracle Gro potting mix today from Canadian Tire to start some of my veggies indoors. Opened the bag and a little black fly flew out. Looked in the bag and there were dozens of them 🙁 Needless to say I’m pretty ticked!
Ellie,
You are not alone 🙂 Frustrating, isn’t it??
No more miracle grow for me. Transplanted 3 banana trees using it and the bats are awful. Went to garden center bought Bonide granuals and plant spray to help kill the bugs. Did not have good results. Hate to get rid of plants but family ready to throw them out. They are all over again. I will never use miracle grow again.
You can get rid of the gnats by using 3 % hydrogen peroxide WITH NO ADDITIVES. The formula is 1 part peroxide with 4 parts water. Water your plants as you would normally. I’ve tried it and it works, the larvae die on contact. It doesn’t kill the gnats but they will die off anyway. I watered with the mix till I saw no more flying around, dead in sills or on floors or in the pots. It is inexpensive and will not hurt your plants mixed correctly and it’s actually good for them. Beats having to re-pot and replace plants. Miracle Grow is horrible and didn’t use to be. I’ve had to do this a many times after re-potting with a number of potting soil brands even with soil at garden centers. Try it, you’ll like it. The solution will fizz up on the soil but that isn’t a problem. The larvae die on contact. Biggest thing is watering long enough with the solution to totally get rid of them. Don’t stop before the real miracle happens.
Thanks, Patty!
Really appreciate this insight and non-toxic trick 🙂
The hydrogen peroxide solution DOES work. I tried it today and you can see the dead larvae on top of the soil after your’e done. I purchased Neem oil and hear it will kill the flies, they’re gross. The only good thing is at least it is summer and I can put my house plants outside until the infestation is killed.
(I got Miracle Grow potting soil too.)
Thanks for sharing! It’s great to hear what works and what doesn’t work for everyone who is dealing with this problem.
Thanks for the hydrogen peroxide and water cure!
Now, what potting soil do you recommend?
Great! Honestly I don’t even use potting soil anymore. I use straight compost. I only use mushroom compost – so maybe it’s more gentle than others? – but I’ve had great success. Buy the bags at Lowe’s for a few dollars or so. This is a comparable brand – http://amzn.to/2npaYTh If you want to use potting soil, I’ve used EcoScraps (bought at Target). I did have a mold issue in one of the bags, but they refunded it promptly without me having to return the bag.
I just realized today that my infestation inside and out is due to my Micracle Gro potting soil! I cannot believe it!! As you pointed out, Kim. It the time and frustration of trying to get rid of those irritating gnats and the heartbeat of some plants being so infested I end up throwing them away. I’m going to try the peroxide trick AND write to Miracle Gro!!!
Please do! I know, it’s the emotional and time connection that seems to be the worst. Not the money for the soil. I’m sorry this had to happen to you, too. It really is so frustrating. Once it’s done, there’s not much you can do about it. Good luck!
Sadly, for me, none of the remedies worked. I have been dealing with gnats for almost a year now because of Miracle Gro Soil. The only option is to throw out the plants. I am tired of gnats flying around, ending up in my drinks, bath water and even worse, up my nose!
Jackie,
Yep, that’s gross!!!!! So sad you have to throw out your plants. I did, too. It’s not a fun feeling!
I’ve heard ‘boiling water’ to STERILIZE soil could kill the ones flying. Have you tried it? I have at least 3 closed bags full of these things! I am disabled so I have to do things in stages, now that I’m ready for my dirt, Miracle grow, my old standby, is full of these flies…
The problem with the killing the ones flying are those aren’t really the problem. It’s the larvae growing in the soil that is problematic, since they will keep breeding. If you have sand or aquarium rocks, you could put on top of the soil which will kill the larvae life cycle. Also, apparently watering from below (like putting the pot in a saucer of water, rather than using a watering can) is suggested to change the life cycle. I don’t know how it works. But it’s suggested by others.
I was planning on giving gifts of plants I have grown! Used MIR GO SOIL NO GIFTS FOR NOBODY!!! Unless they are into flying bugs! Tried lots,, raw potatoe to capture larve,,vinegar to drown flyers,,now trying fly paper,,I may have to resort to sand,,I cant even type here in this forum what I would like to say to miracle grow!!
Billy,
Thanks so much for sharing your story, too. I’m sorry that you’re having to go through that. Hopefully your gifts will turn out all right with your guiding care 🙂
I DECIDED TO GROW SOME HOUSE PLANTS AND USED MIRACLE GRO. I AGREE WITH WHAT I JUST READ ABOUT THE GNATS. I NOW HAVE GOOD OLD FLYPAPER HANGING IN MY APARTMENT AND THE AMOUNT OF CAUGHT GNATS IS DISTURBING. GOT THE STANDARD ANSWER FROM MIRACLE GRO COMPANY, PUT A LAYER OS SAND ON TOP OF THE SOIL. NONSENSE. NO MORE MIRACLE GRO, INSIDE OR OUTSIDE.
Thank you so much, Ernie, for sharing your story, too! With every story like this that is shared, it’s becoming apparent that there are tons of people having this problem, too.
Wow…back in the 90’s I always had houseplants and no gnats…fast forward to 2015 when I retired and decided to go back to my old hobby.I have never in my life had a house full of gnats,they fly up nose,ears,mouth…. Give me a break..that Miracle grow and organic soil is full of gnats. I also qot the vinagar plus I got the Gnat Nix from eBay….u still see gnats crawling on the Gnat Nix in the pot. I put a couple of plastic cups full of water under the plants…woke up a lot of dead gnats in the water because they are attracted to water ,don’t leave a glass of water lying around,there will be a dead gnat in there. Miracle Grow…Shame on you..I will never buy Miracle Grow again…its not miracle grow its Gnat Grow.
I spent a lot of money on Miracle Gro soil. And now I am fighting bugs. I need a solution as to how to get rid of the bugs without losing my plants. I have two large bags.
Same issue here, thought it was bad luck with my choice of plants but realized it was the soil. Note I have amaryllis and rosemary that are infected with these little buggers. Insect soap failed for me as well. Next I tried vinegar and finally is seven if all else fails. I will not be buying miracle grow next year.
Yup, same problem here. bought the 55 gal moisture control Miracle Gro bag at COSTCO. Repotted about a dozen inside plants. Now I have fungus gnats all over the place – on the windows, on the counter, flying around the breakfast table. Going to take the bag back to COSTCO and get a refund. Now I have to either repot the plants with a more reliable soil or get the little powder additive to add to the Miracle Gro soil to get rid of the gnats. What a pain.
Thanks for your story, Wes. Every single time someone else tells me the same story, I know it’s not just a one-time problem. It’s a real issue that needs to be addressed by Miracle-Gro. We gardeners are paying the price, though.
Oh my Gosh Im here thinking it was the cheap stuff I bought,then to here your problem to. But I have to be honest I didnt have that problem till the cheap stuff. But also I never thought it could be the soil . Im off to the nursery for some better stuu than what Ive been using. Thanks girls
Hi–I have since set up a google alert with Miracle Gro, but I had the exact same encounter about two months ago with my houseplants. I had just bought the regular 1cu.ft of Potting Soil from Home Depot (fyi, the moment I grabbed the bag I KNEW I would regret it, but I was in a hurry and didn’t have time to hit my local garden center) I planted about 40 small seedlings of plants and the very next day…infestation started. I tried to fight it with the glue traps and even bought Gnatrol, but to no avail, I had to go through the tedious task of dumping back out all the old soil, rinsing off the roots, resit in water baths, to then wait 2 weeks for the nasty buggers to be gone out my apt. Over all, it took me about 2 months to bounce back. HORRIBLE experience. If you have the chance, go to Consumer Affairs and post a complaint. Finding others out there was a BIG HELP and have really confirmed my own suspicions that Miracle Gro is NOT the best product out there for gardeners, and IMHO now, probably the absolute worst. And also, very sorry to hear about your experience too. I hope you veggie bed bounces back too and you yield beautiful fruit without the help of Miracle Gro.
Pattee,
I appreciate you responding with your experience, too! It’s important to note it’s not the actual cost of the soil that’s the problem, it’s the time and energy and lost plants that are killed because of the soil. All gardeners know how much time and energy and love we put into our plants. To pay our good money for a corporation’s product which destroys all that, and then they just sit and say oh, well, it’s infuriating. We do have a choice and I know that your story will help shape other people’s choice, too! Thanks so much.
THANK YOU, for taking the time to share all your experiences and to educate me and so many others!!!
PLEASE have a great day!
Thank you, Elita! You, too!
I’m writing for my sisters . Two of them bought mulch from Home Depot and they have fungus gnats infestations. They have removed all the mulch and all the plants all the way around the house and they still are infested inside the house it’s a daily chore. Tape on all windows . Cleaner / pest control etc. anyone else. Even pest control professionals don’t know what to do !
Denise,
Ugh! Yes, I don’t know what to tell you. Thankfully ours were outside. If they were inside that would be unbearable. I hope your sisters can get them out soon.
they can also live in drains including sinks and baths/showers so i suggest bleaching all drains then removing the top 1/4 insh of soil and replaising it with about an inch of Sharp Sand this really helped to beat down an infestation of my own. i know sand dosent look to appealing but neither does a house full of flys so i went with the lesser of two evils haha. good luck 🙂
5yrs ago i replanted my really large beautiful plants (about $300 value) in Miracle Grow potting soil. The next day, fungus knats everywhere. The soil was literally crawling. It was so bad, i ended up throwing all of those irreplaceable (some from my Father’s funeral
and my Father-in-laws funeral) very large plants out. Recently, i replanted my houseplants again, was in a hurry, grabbed a bag of Miracle Grow. Now i have the same problem, knats EVERYWHERE, the soil is crawling. Called Scott’s Miracle Grow, ZERO help, just some condescending remarks, told me, to hire a professional to exterminate them from their soil! Really disappointed that a company with such a big name, treated me like my loss was just a mere “inconvenience”.
I agree, Same exact thing happened to me with miracle grow. Fungus gnats! Pain to get rid of, and to have to have paid for all the hassle was miserable. Never again will I buy miracle grow soil of any type. They obviously don’t care about repeat business, as long as they get you the first time.
I was wondering where all these flies were coming from. I bought like 5-6 bags between me and my mom. Great ill try the sticks
Good luck!
The same thing jus happened to me the last 2-3 wks I have fought these flying monsters all over my hse…because of a hse plant I bought with said soil already in it from the store..the plant died 3wks after I watered it, it seemed to get sick.. never happened b4… so I thru the plant away but kept the pot..I went to throw out the soil after seeing gnats swarming it only to find what looked like human hair, actually resembled pubic hair..I’m SO GROSSED OUT RIGHT NOW…I can see maybe putting my own hair in it IF I were inclined, but for some strangers hair to be loaded & I MEAN LOADED DOWN in my soil & I didn’t know it is making me wanna puke & scrubb my hands with bleach…It shud be marked if it’s in thr REALLY…. oh WOW….
That is GROSS. Just really GROSS!!!!! I would never buy from that plant company again, whoever it was. Yuck!