By the way -
It can be tricky cutting big plug trays or propagation trays into rows or segments that are easier to plant out from. Even the rims are tough to cut off, since a pair of tin snips may not fit between the outermost row of cells and a curled-over edge.
I find that using a knife usually slips and cuts down into the walls of cells instead of just slicing neatly between cells.
I have a pair of scissors with thin, long blades. They are thin enough to fit between cells, even in a 200 cell plug tray (10x20 rows). I keep them sharp enough to cut the fairly thick plastic.
The blades are long enough to span 3-4 cells, which helps a lot at keeping the cutting point on the rim between cells. I cut with "small bites", like only one cell at a time. The scissor-blades extend 1-2 cells PAST the cutting point. That keeps the cuts straight and I don't chop down through cell walls.
P.S. If you damage some cells but still want to use them, you can retire one row of cells to use as "patches". Carefully cut a single cell free from the discarded row. Now drop that cell into the damaged cell so that the "chopped" wall of the old cell is blocked by a whole wall of the single free cell. However, note that the doubled bottom of the 'repaired" cell may not easily wick water from the flannel pad. You might need to tuck in a bit of cotton to bridge the gap.
