Please, tell me why I get this fruit flies. I don't know what I am doing wrong. What causes these pests. I have repotted all my plants and sprayed all the leaves and soil with anti-bacterial soap and water as recommended by a professional.I have had plants for years. For some strange reason I am having hard luck. The plants have been growing very slow. HELP!

Your not doing anything wrong. You have what's called Fungus Gnats which resemble fruit flies. They are a common problem even with the best care. The adults and larvae may have been in the soil already when you bought the plants and you just didn't notice right away, and any flying around when you re-potted returned to the new soil you used, or, they are in your new soil.

Go to SEARCH this site and type in Fungus Gnats, where it says, "LAST 30 DAYS" Click "ALL DATES" and keep scrolling down to find lot's of information on what you can do to get rid of them. Keeping the soil dryer will help some since they like moist soil.