It's more common inside than outside. And it comes from the
seedlings getting wet. And yes they are pretty well done for when they hit the dirt.
What kind of herb were you trying to grow?
Usually if you are using a miniature
greenhouse type arrangement to keep the soil moist and you leave it on after the
seedling sprouts you begin having damp off disease show up. So take the "tent" "
greenhouse" off once the
seedlings appear.
It is also more likely to occur if you don't have sufficient light and the
seedlings get leggy. Hope some of this information helped some.
and therefore don;t know how to prevent it!! does it only occru when you have 
