Beneficial Nematodes will eat the Fungus Gnat larvae.

Here is a link that might be useful: GrowOrganic.com

Fungus gnats. Means the soil is being kept too wet. Are you using a fan for air circulation? If not you will find it helps a great deal in both keeping the gnats down. And, of course, cut way back on the watering. Most way over do it anyway and that is the most organic solution for eliminating the problem.

Otherwise several different organic based sprays are available including Dormant Oil spray (used only on the soil) and BTI (Bacillus thuringiensis israelensis) sold as Mosquito Dunks and Mosquito Bits under the Bonide brand.

Dave

mustgarden, if you have the fungus gnats now, I doubt if you will be able to let your seedlings dry out enough, for long enough, to get rid of the larvae without damaging the plants - better is to not keep your medium too wet to begin with.

I'd go with the BTi - Gnatrol, Knockout gnats, Bonide mosquito beater, or if you cannot find any of those locally, pick up some mosquito dunks and make your own solution - float a dunk or piece of dunk (no need to be precise) in a container of water overnight, then use that water to water your seedlings. It's not a 24 hour cure, it can take up to three weeks of consecutive use each time you water before you have broken the breeding cycle and are seeing no more gnats. Don't worry about the adults, they live just briefly, you want to stop their larvae, larvae that will feed on fine plant roots like the types seedlings are developing.

Thanks everyone. The fan is on and I will definitely be more stingy with the water. Tomorrow I'll see about finding one of the solutions you've suggested.