"dps" wrote in message
...

You don't describe exactly what happens to your plants. Is it damping off?
You can reduce damping off dramatically by just putting a fan in the room
where you're starting your seedlings. The air circulation will remove
humid air at the air-soil interface where the damping off fungus takes
hold of the plants.

Along with air circulation, it helps to add some bottom heat, using heating
cables made for this purpose. It doesn't eliminate fungi, but it accelerates
sprouting. If the seedlings reach a certain size more quickly, they'll often
"outrun" the fungi.