Question
Recently I replanted all of my house and office plants. about 3 weeks later I have flying nats (Little flying insects) in my house and office.I have tried to get of them by spraying them with Houseplant & garden insect killer (Schultz Garden Safe) It's not working. I have been spraying them daily ,however I have gone threw 4 bottles of spray and i still have them.
Do I need to replant all of them (various sizes) How do I kill them without killing all my plants? Some one told me to lay a fine layer of coffee on the soil, does this work with-out killing the plants. I do not over water them and let them dry out for a few days before watering them. Help these bugs are driving us crazy.

Answer
Leslie,

I suspect that when you repotted you moved your plants to too large of pots and that you may have used a potting soil with too much peat moss so it holds too much water. Both of these factors cause you to be overwatering without realizing it. There are only 2 ways to tell if a plant is dry 1-use a water meter and insert it into the soil so it is within an inch or two of the bottom and do not water until the meter reads dry at that depth or 2 - insert a bamboo skewer and check it before watering, do not water until the skewer only shows moisture on the bottom 1-2 inches.  When you repot plants you should only move them to pots that are 2 inches larger in diameter than the pots you are removing them from. If you moved your plants to pot more than 3 inches larger than the old pots I suggest that you move them back to smaller pots. Any plants that you move to smaller pots or any you repot in the future you swhould mix extra perlite with the soil to make the soil lighter and it will eliminate your problem with fungus gnats. Mix 1 part perlite with 2 parts potting soil and use that for potting all plants except cactus. For cactus you should add 1 part builders sand. To kill the insects immediately you can water the plants when they are dry with rubbing alcohol and that will kill any insects in the soil. If you follow my instructions above it will eliminate future problems. Good luck.

Darlene