Hi, I have lived in Oregon, Washing and now in Anchorage Alaska and the one pest that seems to thrive is fungus gnats. About a year ago I learned that if I put 3 or 4 drops of mouthwash in about a quart of water and water my plants with that, it keeps the fungus gnats out. One may come in from outside and try to lay its eggs in my soil but with the mouthwash in it they do not live. I also put about 1/2 to 1 inch of sand on top of my soil to help with this problem. So far a year later and I am fungus gnat free. Just thought I would share that.
I have also used dishwashng liquid in some water and sprayed the top of the soil really well...it coats those little things and smothers them. Soap would also work. I also take a paper towel with some soap or dishwashing liquid and water and wipe the leaves of my plants inside and out and underneath. I only had a fungus gnat problem when I was using sphagnum moss. Those days are long gone... :)
I have never had gnats on my houseplants before. They are flying and crawling on the plants. Are these the fungus gnats that everyone is talking about? That is the only problem I have with my plants!! I was thinking about trying the soap and water. This IS ok for all houseplants right? I want to make sure!!! :) I have tried different houseplant insecticide and nothing seems to get rid of them permantely!! They will go away after I use that but then usually come right back!!! Thanks!!
bacillus thuringiensis israelensis. It's the same ingredient in mosquito dunks. Buy it in liquid form labeled Gnatrol or there's another liquid brand you can buy at the pond supply store for mosquitos. 2 drops in a quart of water sprayed all over your growing areas, especially on the soil. 2 drops lasts me about a year.
It's a natural virus that is harmless to humans. Much safer for us than even mouthwash or soap. It's the wonder cure for gnats. :)
The soap and water generally worked for me and I made sure I used it at every watering until the eggs and knats were erradicated. It did not hurt the plants. You may want to repot in fresh soil, because sometimes soil comes already infested with eggs from these things.