Brooding On

Cold Frame Issues

We came home from a weekend away to find that our cold frame had taken a tumble.  While I'm not sure how long it had been down, the greens inside were still alive.  The poles hadn't snapped, so we were able to just reposition them. 
The duck tape used to hold the two pieces of plastic sheeting together had come loose, though.  It seems to have lost its stickiness.  Maybe it can't tolerate the cold?

We went ahead and re-duck taped because I wasn't sure what else to do.  Any suggestions for another way to keep the two sheets together?