Half way though rolling, fold up the bottom. Finish rolling, label, and rubberband the paper pot together. If the plant is small and you cannot determine where to cut the crown, it is far better to dig up the plant to make a more informed decision. For larger plants, they are more forgiving if you make a misplaced incision. Your calamagrostis 'Karl Foerster', calamagrostis 'Overdam' should be in the process of beginning to plume.
Clumps are much more attractive without last years dead material.
Deschampsia cultivars are most likely at their full height awaiting their plume. This weekend I collected 3 new carex and one rush. I have another 6 different kinds of grass that I have collected during the spring months that have yet to be planted. I think the varieties of grass will one day overtake my hosta collection. On well, lawn mowing just takes shorter and shorter and shorter . . .