Name: Ronnie (Veronica) Southeastern PA (Zone 6b) Count your blessings, be grateful
It's best to put drainage holes in anything you use unless you do the vermiculite method. I don't use that because they have to be transplanted sooner than the others in dirt and I'm not always ready. I agree with Jennifer it is best if the tops are clear.
I direct sow a lot of my seeds but don't cover them. I guess you could use the light row covers.
Kindness is the language which the deaf can hear and the blind can see.