I need to get rid of all the junk and clutter in this house, not collect more!
I use a big old flat serving tray when I plant. It's length is just about an inch shorter than a flat. When filling the edge of a flat, I just need to slide it an inch left or right. And it works great for planting pots.
I also do my planting in my ugly unfinished basement so no big deal if I spill stuff. I just sweep it up from the concrete floor easily. When planting in summer I do it on a small table in the yard, under the shade of a tree.
Karen