I've been dealing with a fungus gnat invasion since July, affecting about 15-20 of my plants, and I'm feeling pretty overwhelmed. I've tried various methods like using Mosquito Bits and yellow sticky traps, and I make an effort to bottom water while allowing the plants that can handle it to dry out a bit. I also cover the soil with gravel or pebbles for some plants, and for others, I sprinkle a layer of cinnamon. I spray my leaves with hydrogen peroxide, neem oil, or cinnamon oil, but just when I think I'm making progress, the gnats come back, specifically when I see their larvae on my plants. Most of my plants are in plastic pots with plenty of drainage holes, but I started to wonder if the holes could be part of the problem when I noticed some adults in the decorative pots. Do I need to switch to pots with fewer drainage holes? Is it okay if they lay eggs in soil treated with Mosquito Bits tea? I also ordered diatomaceous earth, but I've heard it only works if kept dry. I could use some guidance on this!
1 Answer
I've dealt with fungus gnats a few times and successfully got rid of them by using Mosquito Bits and yellow traps like you do. The main difference is that I don’t bottom water. I think bottom watering might allow the pests to hang around longer since the poison isn’t washing through the soil. In my worst cases, I’ve let the plants soak in the runoff from the Mosquito Bits, which isn’t ideal since it risks root rot, but it was effective in keeping the gnats at bay.
Thanks! I think I'll try that next time. You've defeated gnats multiple times, so your method might just work! I could also try moving the top layer of soil out, watering, and then putting the layer back to keep it dry.