Should flats have plastic on bottom to stop water loss?

[Bobberman]

When you move your seedlings to flats it seems like the small 6 packs loose water fast! Should the flat be put into a plastic bag then the small inserts with the seedlings on be placed on top! Holding water longer should aid the new plants from drying out. Some flats I guess are made without holes in them! Any suggestions?

[bogydave]

Is use tight trays when I start seeds & have a cover on them too, but after the sprout I don't.
I've lost plant due to over wet soil & the roots rot. I give them drink & let the excess water drain out. wilted pants come back fast if they go dry, if checked daily.
Just my way, but like I mentioned i killed some from over water so now I use holey trays.

[lily51]

I agree, root rot can be a real killer, especially early in the season before things heat up. Also, check plants and greenhouse temp several times a day if it's a sunny day where heat can really build up.