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I am new to the world of gardening/planting. I had a huge bag of potting mix that I bought from amazon last summer and used to plant some herbs. I used half of it back then and kept the rest in the bag. The bag had holes in it for breathing so I thought it would be safe to keep it out on the balcony over the winter (in a secluded area away from snow and rain) since I don't have a place for it in my apartment. Long story short, I was just checking the bag to get ready to plant new herbs for this season and I was shocked to see that the bag was full of tiny flying insects.

I read online that it might be fungus gnats, but I didn't see anything online about them being in the bag itself. I was wondering if there is anything I could do about this issue or if I should throw away the bag and buy a new one? I would appreciate any input regarding this matter!

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adelejjeh
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    Fungus gnats are usually only a problem indoors in houseplants that are kept too wet. If your winters are cold and the potting soil has been outdoors, not sure what the insects are - don't suppose there's any chance of a photograph of these insects? Which particular type of potting soil is it? – Bamboo Mar 23 '17 at 00:03
  • Bamboo I would think this should be an answer. Definitely a picture of insects because if I were an insect with nice warm soil with lots of food that is exactly where I would go. Don't think it will be a big problem but even fruit flies inside make me go crazy. I do get to practice my speed and timing trying to smack them in the air!! Maybe it is just an insect that will fly away and never be a bother again...unless it has already made babies, they do that quickly. Grins.! – stormy Mar 23 '17 at 16:38
  • @Bamboo I added a picture to the main post. – adelejjeh Mar 23 '17 at 16:47
  • @Bamboo They are very tiny insects, not larger than the size of an ant. They seem to be black with light-colored wings, kind of like tiny flies. The type of potting mix is: "Miracle Go Organic Choice Potting Mix". I live in the midwest, so it is very humid during summer/fall. I wanted to mention that during summer/fall I've opened the bag once or twice to find a white residue on top of the soil. A quick internet search lead me to deduce that it was fungus. I removed a lot of it back then and left the bag open in the sun to get the moisture out; I'm not sure if this is relevant. – adelejjeh Mar 23 '17 at 16:47
  • @stormy it seems like it made babies since there are a lot of them roaming around the bag! I guess you can say they kind of look like fruit flies. At least same size/shape. – adelejjeh Mar 23 '17 at 16:48
  • You do not want flying insects in your home. Really go get another bag. I can't see what they are by the picture but the whole idea with potting soil is sterilization, so you KNOW what your plant is getting and flying insects indoors is a major headache. The white is fungal mycelium, no big deal. I'd go get a new bag. Your plant and outlook with gardening are far more valuable. – stormy Mar 23 '17 at 16:54
  • This is just fine to use in pots out on your balcony however! I assumed you were planting stuff for indoors. Really, no big deal at all, use for herbs outdoors in pots for sure!! – stormy Mar 23 '17 at 16:55
  • @stormy I'm just worried about them affecting my plants since I am planting edible herbs. Do you think that would be fine? – adelejjeh Mar 23 '17 at 17:06
  • Yes, it'll be fine to use for herbs outdoors. – Bamboo Mar 23 '17 at 17:46
  • Absolutely, adelejjeh! Just don't plant tiny plants in big pots, don't put any additives in your soil, don't put rock or gravel beneath the soil and above the drain hole. Put tiles or something to lift the bottom of your pots above the surface of your balcony or patio. Start in tiny starter pots with fresh soil and up pot when roots come out of their drain hole. Keep doing that until they are in 4 to 6" diameter pots before transplanting into larger pots. Do not over water and use good old OSMOCOTE 14-14-14 for fertilizer. Use once every 4 months if your season lasts that long. – stormy Mar 23 '17 at 18:39
  • Thanks @stormy. I actually get the pre-grown organic plants from the supermarket (Walmart or Meijer) and just transfer them into the pots. I have a hanging pot which I hang on my balcony railing and another large one which sits on the ground. I might be getting another hanging pot this year. The pots that I have still have soil in them from last year, can I re-use that soil and just clean out the remains of any old plants from it? – adelejjeh Mar 23 '17 at 23:39
  • I would not. Plants in pots ONLY have the little bit of soil they get from you. Always use clean soil from bags. One of these days you need to look into NON GMO plants. Very big deal and the only way to be sure is to find non gmo seed to grow your own starts. Hey, I have used starts from stores as well but GMO is becoming so prevalent it is my responsibility to bring it up. My dog died because of gnarly tumors from cheap dog food she got...my other old dog is full of tumors. I've never had tumors on my animals. Look for NON GMO labeling for your own foods as well... – stormy Mar 24 '17 at 00:02
  • 'Organic' means nothing these days. Look for NON GMO labels... – stormy Mar 24 '17 at 00:03

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Well, welcoming a certain degree of "bonus wildlife" is in the spirit of the organic approach your choice of this mix implies. A healthy soil is a living soil. It's astounding what quantity and variety of microscopic critters live in soil, doing good things or at least no harm.

Since these little insects apparently thrive in your bag of soil, that suggests though does not guarantee that they eat dead plants (detritivores). Compost = dead plants. Some insects eat both live and dead plants, but lots stick to one or the other only. I'd cut a bit of almost any plant, nice juicy green leaves, and maybe put the stems in a little glass of water. Nestle the experiment into the potting mix. Leave the bag open, mimicking the air that a potted plant would have. Then look in a day or two and see whether the insects congregated on or obviously damaged the leaves. If not, I'd use it as is. I certainly wouldn't throw out the bag.

If you really, really want the insects gone and suspect there are eggs, another option is to put a bunch in a big pan and bake it at about 250 degrees until it's hot through. Warning: This can really smell up a kitchen!

On good rumor (I'm not taking on Miracle Gro with an absolute assertion!), they make at least some of their organic potting material by composting ground up ponderosa and lodgepole trees from the Front Range in Colorado, or did a couple years ago. If that's what you happen to have and forest conifers are the origin of the insects, the chance the insects also favor tiny tomatoes seems low.

user17549
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  • So I ended up using the soil to plant my herbs. The insects are all over my basil but they don't seem to be harming it. I do see a few brown dots on the leaves here and there though, I don't know if that's a "disease" or if it is from the heat of the sun. I'm starting a new post with a question about some of my plants so I'll move this issue to that thread. Thanks for your answer though! (And sorry I saw it late!) – adelejjeh Jul 12 '17 at 14:44
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I would not recommend tolerating fungus gnats in soil that you intend to use indoors, unless you like the idea of cohabiting with gnats, as they will stick around as long as you let them. If you want to use that soil, drench it with BTI when you bring it to field capacity. After you've used it to pot whatever you're going to plant, spray the plant with a pyrethrum spray. Then cover the topsoil with sand or vermiculite.

May sound like a lot, but a fungus gnat infestation indoors is hell.

Nate
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