I started out my first seedling bed without any mulch.
I can agree about mulch being a harboring spot for slugs.
However, we are still on drought watering restrictions here, my seedling beds are on drip, and I decided that maybe the prudent thing to do was to help conserve the soil moisture by mulching (plus it makes the beds look better, while the seedlings are still young). I was also having problems with the first few blooms opening in my unmulched first seedling bed. That
could have been due to not enough soil moisture, or it could have been due to our still cold nights. I can't do anything about cold nights, and I'm not supposed to be watering more
, so conserve what water does go into the bed. (The conservation of soil moisture might also help with the overall growth of the seedlings, which in turn I hope will give me bloom on most, if not all, seedlings within a year.)