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Which brand of potting soil does not contain bugs?

10 years ago

I just purchased a bag of potting soil and found bugs in the bag. Fungus gnats are the worst, and last year had a big breakout of them! Didn't used to have this problem in the mid 2000's, but now every bag I've purchased recently seems to have them. Suggestions?

Comments (33)

  • 10 years ago

    You haven't mention the brand but my suggestion is "Buy a different brand".

  • 10 years ago

    NONE of them should contain bugs of any sort!! I agree with gumby -- and I'd take the bag right back to the store & demand a refund! I never have had this happen.

    Do they fly out of the bag when you open it?? There are ways to control fungus gnats once you have them, but potting media should be sterile - which means nothing living in it at all!

  • 10 years ago

    The brand is MG, their potting soil. It has happened when I lived out west and now on the east coast. (In fact, I overbought in CA, and saved the bag. Was completely infested with fungus gnats when I went to use it about a month later. Some had hatched inside the house, and a LOT had hatched inside the bag.) Yes, the store said they would give me a refund when I called in today, so that's fine.


    I've seen Black Gold and maybe I will try that instead....

  • 10 years ago

    I know how I am and I would not be giving them any more of my money.

    Good Luck to you.

  • 10 years ago

    I mostly use Pro-Mix Ultimate Organic Mix that I buy at Menard's here in Ohio. I either use that or often make up my own using a mix of coir or peat, perlite, and vermiculite for seed-starting. When potting on I use the same mix but add vermicompost from my worms and also some leaf compost that I get by the trailer load from our local municipal compost facility. I have been using that for a long time and am very happy with the results.

    If you go to the Pro-Mix website, they have a store finder option.

  • 10 years ago

    Plant Lady, it just dawned on me to wonder if by MG (which I never heard of) you mean Miracle-Gro?? That, as far as I am concerned, explains everything. I buy NOTHING that they have anything to do with.

  • 10 years ago

    After a horrible experience with Miracle Gro Organic Potting Mix last summer, I'll be following Weedlady's advice and going with Pro-Mix. Not only did I have fungus gnats in last year's MGO, but nearly every single pot struggled. Something I'd not encountered in past decades of gardening.

  • 10 years ago

    When you deal with the realities of contract production, you might find that every one of those different brands were produced by the same plant according to a very flexible recipe whomped up by the brand name's office. Nobody is going to $hip a bag of compost all that far.

  • 10 years ago

    The only way to be sure there would be no insect eggs in potting soils would be to heat that potting soil to between 120 and 150 degrees F and no potting soil manufacturer would do that because of cost. Understanding something about Fungus Gnats may be of some help.

    http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7448.html

    kimmq is kimmsr

  • 10 years ago
    last modified: 10 years ago

    Two other ways to kill off insect eggs are using either a microwave or an outdoor propane grill. Either can be an old(er) model no longer used which you can re-purposed for the task. This can also be a way to kill weed seeds.

  • 10 years ago

    Pretty much any potting mix that contains peat is going to have fungus gnat eggs to some degree including Pro-mix BX (which is what I use). Pro mix doesn't seem to have nearly as many as other brands though. A good way to get rid of them is to water with water containing Mosquito dunks ( a form of BT that kills mosquito larvae as well as fungus gnat larvae). I also use the yellow sticky tape things near my grow setup to catch the adults.

  • 10 years ago

    My thoughts, for what they are worth... I just looked up both the Pro-Mix family of companies (part of the ICL group) and Miracle-Gro ones (MG is part of the Scotts Company). (I did this with great misgiving as I now will very likely start seeing pop-up ads from MG which I will find most aggravating and unwelcome.) While corporate relationships are confusingly convoluted, the two do not seem to have anything in common or to be connected at all.

    The Pro-Mix I use (mentioned in my earlier post) lists the following ingredients: Canadian Sphagnum Peat Moss (65-75% by volume), Sea-based Compost (from composted shrimp shells & seaweed), Limestone (for pH adjustment), Perlite, and Mycorise® - endomycorrhizae inoculant.

    Now, in the first place, in order to make compost, the ingredients, whatever mix they may be, must heat up naturally (thanks to microorganisms of various sorts, especially thermophilic bacteria) to the requisite temperature for killing insects & larvae, etc. Compost facilities take care of the necessary turning of the pile to ensure everything is decayed. No packaging company should have to heat the compost again. Now, maybe an unethical company would not be concerned about obtaining properly made compost (therefore, by definition, not compost at all!), which could then result in infestation problems.

    Secondly,I would think that the actual amount of compost in a potting mix is quite low; peat is the chief ingredient. But I'm guessing that since many gardeners have heard that compost is great stuff, some companies add a little with the idea that they can put that on the label & tout that to the buyer. (Of course, there need be no compost at all in a seed-starting medium since fertilizer is unnecessary for simply starting seeds.)

    Third, compost surely is being produced in great commercial quantities at numerous sites across the globe so there should be no need to ship it any great distance. The other main ingredients of potting soil beside the chief component [peat], vermiculite & perlite are, well - light, if bulky.

    In any case, I have to disagree with grubby's statement, "Nobody is going to $hip a bag of compost all that far." The stupidity of shipping commodities great distances in order to fulfill balance of trade or whatever is boundless. Cases of water (or roof tiles or marble slabs, or...) from Italy and France, shipping U.S. chickens to China to be processed & shipped back here -- the examples are legion. :-) Though as I pointed out above, compost probably does not have to be shipped from very far away. But I digress...

    Finally, any conscientious supplier of potting media will ensure their product is free of pest material AND toxins of any kind. My point being that as a whole, Miracle-Gro has proved itself to be NOT a conscientious company - as have a whole list of companies. See this link http://www.sludgenews.org/about/sludgenews.aspx?id=5 and especially note that Miracle-Gro contains sewage sludge. Anyone who does not find that upsetting should look into that substance and also note that the FDA considers sludge OK for use in an organic garden. No, thank you.

    My apologies for such a lengthy post.

  • 10 years ago

    They're collecting cases of bottled water here in MO to truck to Flint MI, so I would have to agree with you about the state of the commodities markets and shipping these days. [BTW I'd love to help Flint but the money would go farther if they bought water closer to the destination. They'd deliver more water and spend less on shipping.]

  • 10 years ago

    As a resident of the city of Flint, I'd like to thank everyone who has helped our city with the water supply. I read one article that stated if we watered with the poisoned water we needed to remove the soil and replace it. Now I'm planting all flowers. Thank you everyone for your views on MG and other products.

  • 10 years ago

    Thanks Mari for your kind words. We all feel for you folks.

    If you are concerned about your soil, it is very inexpensive to have it tested for lead. Contact your county Ag Extension office, or county Health Dept. and ask them how to get it done inexpensively. They will tell you how to collect a representative sample.

  • 10 years ago

    I got curious about this issue Mari so here are some numbers for you. Let's say you are watering with 100 ug/L (100 ppb) Pb which is in the ballpark (actually the upper end) of what I have heard for Flint water. Now a max. safe level of Pb in soil for residential use including gardening is 400 mg/kg (ppm) according to EPA. Background is probably way under 50 for Michigan. Let's find out how much of that water it would take on a 10x10 ft plot to raise the Pb concentration in the top six inches by just 100 ppm. Turns out to be 52,000 gallons according to my calculations. That is a LOT of water. Unlikely you would ever have used that much. If you watered for 6 months out of the year for two years (that's how long since they changed to the corrosive river water, right?), that would equal 144 gallons per DAY on that 10x10 foot area. Almost 3 of those 55 gallon drums worth.

    So they're being very conservative in making that recommendation. Before abandoning gardening, I'd get that $20 soil test if I were you.

    In fact there is probably a lot more lead in the soil around older houses in older cities from leaded gasoline emissions and lead paint flaking off the houses than there is from watering with Flint water.

  • 7 years ago

    I've had similar issues...and I've tried different brands. One local garden center told me that it was probably because I purchased Miracle Grow...so I bought one they had....'something GOLD' can't remember the exact name. Well, theirs had gnats too! I just bought a bag at Walmart, because I needed a quick bag of potting soil...and as soon as I was unloading it from the car I noticed bugs flying out! Since heat is important...I'm wondering if possible putting it in a large black bag and setting it in the sun would kill the infestation? Has anyone tried that?

  • 7 years ago

    Peat based potting mixes will always be prone to fungus gnats.....it is just the nature of the beast and it doesn't make any difference with brand names. It is the moisture retentive attributes of the peat that attracts them, the damp soil makes a good larval incubation chamber and is a source of food as well. The infestation can occur at any time but typically with the suppliers (not the manufacturers) and when the material is stored out in the weather.

    The way to get around this is to develop your own custom potting mix that does not rely on peat as the primary ingredient. Both the 5-1-1 and the gritty mix discussed at length on the Container Gardening forum will work well, as they are both fast draining and rely on bark fines and/or mineral products rather than peat or coir or compost (all moisture and food sources for the gnats) to accelerate drainage yet still provide a necessary degree of moisture retention.

    Heat from sun will not kill them but the drying of the soil mix from sun exposure will certainly discourage them. It is the moisture they thrive on. Flushing with a dilute solution of 3% hydrogen peroxide (part hp to 4 parts water) will also kill off the larvae.

    FWIW, I have been using the 5-1-1 mix for all my containerized plants, both indoor and out, for over 20 years and I never have issues with fungus gnats!!

    btw, other than some brands of seed starting mix, potting soil is seldom ever sterilized :-)

  • 5 years ago

    Ive used pretty much every brand of potting soil I can think of, and I've heard nothing but bad things about Miracle Grow, everyone I know who uses it complains of bug infestations (fungus gnats). Not worth wasting your money on that brand. I've use Promix for many years and they were great for a while, but the last batch I bought, had a major infestation of fungus gnats, I was able to get rid of the bugs with Neem oil, water and soap solution, then I put a layer of DE (diatomaceous earth) on top of the soil in my potted plants. It was quite the battle, but I eventually won. I also placed a lot of yellow sticky bug traps to catch the flying adults (they look like fruit flies). The gnats don't eat the plants, they lay their eggs in moist or over watered soil. Then the tiny microscopic maggot-like larva that hatch from their eggs, eat away at the fungus and the roots in the potted plants. Each fly can lay up to 300 eggs, so it can end-up being quite the battle. The DE dehydrates them and acts like tiny microscopic razor blades that shred their bodies when their larva try to move around in it. DE It is completely harmless to humans and plants.


    Like I said, I finally wont the battle, got rid of the bugs, but all those treatments take a toll on the plants. Neem oil foliage sprays require soap to get the oil to mix with the water and that can be really hard on the plants. I beat the bug problem, but unfortunately my plants took a bit of a beating.


    I think Promix was always the best potting soil, but if you get a bag from the store with holes in it, forget it, it will be infested. Everything is about the money, these companies don't really care. Most people never figure out that the bug problems they have came with the soil, because that soil is supposed to be sterile, but it isn't. Promix is just as bad a Miracle Grow these days.

  • 5 years ago
    last modified: 5 years ago

    I suspect half the problem with MG potting mix is that it's too fine-textured, which is something that container experts here often mention as being not good for plants anyway. As a result it gets very soggy and doesn't dry out fast enough, and the fungus gnats thrive in the wet conditions. Container mix should be coarse enough that the surface, at least, dries out between waterings. If the stuff you get looks like finely sifted compost, it's not ideal as a potting mix. I like to add shredded bark to mine, or fine wood chips, or the coarse siftings from the compost pile.


    EDIT: PS - Initially it cracked me up that anyone was looking for an insect-free gardening experience. However, bad fungus in known crappy-quality container mix is not such a laughing matter.

  • 5 years ago

    One rarely finds bagged soil from the garden center heavily contaminated with fungus gnats or other bugs simply because of the environment. From start to finish, fungus gnats have a very brief lifespan - only 3-4 weeks - and in any of their life stages, will not survive long in a closed, bagged environment. Torn or water saturated bags may be different but I'd avoid those anyway.

    But they do transport inside easily from outdoors where they are happy in any moist, organic debris and extremely cold tolerant as well. And once inside they will happily colonize any containerized plant with consistently damp potting soil. tox's suggestions above for increasing the drainage of bagged potting soil and easing off on the watering, especially in winter, will help to make a much less desirable environment.

  • 5 years ago

    I have bought soil from menards walmart I believe if they are outdoors the bags have small air holes they get in it I have dumped 4 plants then 2 more the begonias and wandering jew were the worst they are in water now til spring I used mosquito dunks also still seem to hatch out :(


  • 5 years ago

    With mosquitos? That's odd, and the dunks should take care of it quite handily. If they're fungus gnats instead, I'm not sure if mosquito dunks kill those.

    Fortunately, fungus gnats are easy in soil. Any minor insecticide, neem oil, and often just soapy sprayed water, will kill them. The larvae live on in the soil, so a mix of 1/4-1/5 household hydrogen peroxide (3%) to the rest water, and water the plant, will take care of those. The combo won't damage most plants, but check to see if they're sensitive to either hydrogen peroxide or whatever method you're using up top.

    If they come back, repeat it again. They usually won't if you hit all the plants or soil at once. If you don't, then one of the remaining plants actually had a few gnats in it.


    Hydrogen peroxide (H2O2) naturally breaks down to water (H2O) and oxygen (O2) over time. So also make sure to use fresh, or at least properly stored, hydrogen peroxide, and only the 3% version available in the first aid section of your drug or grocery store. It isn't good forever.


    The same mix of H2O2 can be used to treat minor cases of root rot, but it's not terribly reliable. For minor cases, it can work, however.

  • 5 years ago

    Bti kills both mosquito larvae as well as the larvae of fungus gnats (not the adults - for those I hang yellow sticky traps near the plants). Info on Bacillus thuringiensis israelensis

  • 5 years ago

    Pro-mix HP peat growing MD is good . Use for low light conditions and grow in most types of plants .

  • 5 years ago

    I seriously think this is related to Covid-19...maybe something related to the dirt sitting too long, etc. I have had plants in my home for over a decade. This year I have been forced to try neem, hydrogen peroxide water 4:1 mix, and changing the soil. Nothing has been permanently effective. I am down from about 8 plants to now one and a few I am propagating from cuttings because I had to throw the infested plants out 😢. Even the cuttings have gnats and their in a terrarium! Further proof that this has all started from gnats in the soil. Unfortunately I will need to move to artificial plants until I can get uninfested soil.

  • 5 years ago

    Try putting your bag of potting soil into a large clear bag and leave it out in the sun on a hot day for a few hours. The temp inside should get up to 120+ and kill any critters in it.

  • 4 years ago

    I had one, and only one plant, a snake plant, which was in the same pot and same soil for 20 years. It always did well and, honestly, I'd never heard of fungus gnats. The plant was clearly root-bound for a few years -- flowering a few times a year because of the stress. Though it continued to do really well, I finally took pity on the plant and repotted it using Miracle-Gro soil. Within days I was dealing with a *massive* infestation of fungus gnats. Those buggers have survived yellow sticky traps, hydrogen peroxide, neem oil and mosquito bits. And, the once flourishing plant has stopped growing.


    I hadn't seen this forum before buying new soil today, and had no idea Miracle Gro was so problematic. Unfortunately, it is all they stock in my area of NYC, and I didn't know better. I'm going to make sure to bake it and treat it with peroxide before I use it.

  • 4 years ago

    In case you haven't already found out, never bake any type of soil material in an indoor oven. The smell will drive you right out of the house.

  • 2 years ago

    I just had an outbreak of several different bugs after buying HP

  • 2 years ago

    I just had an outbreak of several different bugs after using HP

  • 2 years ago

    Pisses me off!!! im going back to coco

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