Maybe you can find some suggestions in one of the posts in this forum (see link below). If more info is needed, re-do the search and include all the GardenWeb forums.

Here is a link that might be useful: Search for Fungus Gnats in the Propagation Forum

Mosquito dunks in your watering can will help in getting rid of most of them. Gnatrol works well, but is more expensive and harder to find, unless you order it online.

Mosquito dunks contain imodacloprid which is poison. You would be better off to quit overwatering or try a soil-less medium. Wet peat is where your problem is.

Just thought that I would add...if you are looking for some measure of control with out harmful chemicals I would suggest hanging glueboards around your growing area.These are the kind used for catching rodents. If you want an even simpler solution then I would go with Vaseline spread on a piece of yellow or white cardboard. Works well but is not a perfect solution.

Mosquito dunks only have BT.