Answer: It sounds as though you have a huge population of fungus gnats and they're having a great time living off the decaying organic debris and moisture in your potting soil. They are difficult to control because you're providing warm temperatures, moisture, and plenty of food to sustain them. They won't harm the plants, but they can be a real nuisance. Try to put up with them until the weather warms up enough to take your seedling flats and houseplants outdoors. Then you can "shoo" them away by disturbing the surface of the soil and letting them fly into the great outdoors. When you finally plant your seedlings outdoors, you'll be removing the source of food for the gnats and they'll leave quietly. To keep your houseplants from harboring the fungus gnats, try to put a barrier over the top of the soil, like a layer of rocks or shells, so the gnats can't settle into the soil to feed. If all else fails, take your houseplants outdoors for a while this summer and allow the little critters to find new homes.
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