How much boric acid do you sprinkle on the dirt of your house plants to get rid of those little flying dirt bugs?

Answer 1

None. Boric Acid is for wall voids, etc. where hands can't go and is ineffective when wet. Fungus gnats breed in the soil and rely on overwatering to survive, if you reduce moisture to only what the plant needs, they should dissipate. Placing in direct Sun also helps dry them out. If you have many plants, I would use a granular that dissolves slowly with the water you add (reducing amount from previous) which should sped things up. Talstar is one if not the most potent granulars readily available. Use the Boric to prevent roaches in your kitchen, you can dust out all the cracks etc with a hand duster.

Answer 2

You can sprinkle a thin layer of boric acid on the top layer of soil in your houseplants to help control fungus gnats. Use caution as boric acid can be harmful if ingested. Make sure to follow the manufacturer's instructions and keep pets and children away from treated plants.