Primrose cut back

The Primroses have mostly been cut back. They were overhanging the narrow grass strip that allows one to pass from the front yard to the back. I tried holding them back with a string line, but the plants were too top heavy. Some of the plants have grown to five feet in height! There are still quite a few that are left and are still blooming away. They seem to do fine as a cut flower by the way even when left in 80 degree heat. I expect there to be quite a bit of regrowth over the summer, so it should all work out. I think that primrose needs tall supporting plants around it to hold up to heavy wind and rain. The first plant of this species I have is supported by a chain link fence -- it also hasn't bloomed yet so the additional weight isn't there yet.