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fungus gnats- those pesty buggers!!

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  • fungus gnats- those pesty buggers!! member here :oops:

    ok i have an little issue with fungus gnats. They've pretty much taken over my plants and it's not pretty!!!(they don't pay rent)

    so i need some advice from houseplant owners who have battled with gnats before....
    i read somewhere that if you put a thin layer of sand on top of the soil it works to keep it dry...but i don't want sand getting in my soil to upset my plants , so what i did was put small little pebbles instead.....anyone ever do this??
    will it work?? will it have the same effect as the sand??

  • #2
    Hi Jiorji,

    Not sure if the stones will work. Take a look at this site for help.

    Good luck - been there!


    • #3
      The sand works because the sharp edges carve up the larvae as they move about the surface of the soil. The stones will not work.

      Adult fungus gnats fly around and are an annoyance, but they are not harmful to people. Each gnat lives for about 5 days. The trick is to get rid of the next generation - the gnat larvae that live in the top layer of the soil. The larvae feed on decaying organic matter. Decaying pine bark in potting mixes and decaying plants roots feed the larvae.

      Try to keep the soil as dry as possible. Remove all loose soil from the surface and put a light layer of coarse coir (coconut husk) or sand or diatomaceous earth on the soil surface. These substances have sharp edges that carve up the larvae. (Recent studies indicate that fine-textured peat moss also deters gnat larvae.)

      Another safe technique is to place ½ inch slices of raw potato on the surface of the soil to attract the larvae. After a day or so, discard the slices along with the larvae inside. Repeat this until there are no more larvae in the potato.

      For more serious infestations try Knock-Out Gnats to treat fungus gnats available from Gardens Alive for about $20. See

      Another bio-control method is Gnat Not, a parasite that destroys gnat larvae and other soil insects. It comes on a sponge in plastic (5 weeks shelf life) that is rinsed into water and applied to the soil. For information, go to

      Detection trick: Add a little water to the soil and then look very closely for tiny fungus gnat larvae swimming in the water as it pools on the surface. You need good light and good eyes to see them. If you don't, then your plant is probably gnat free.

      Prevention is often the best remedy. Use sterile potting mixes that are free of bark chips. The potting mix should have ample drainage material, such as perlite so that it drains well and allows the soil to dry out frequently. Fungus gnats can nearly always be traced back to overwatering and/or poor soil quality.