What is the best way to handle grape plugs not grown is RootMakers, left too long in the container with tightly wound roots?

I have studied this issue at length and with an assortment of species, but not with grapes. But, from my years of experience, which included studying and growing grapes in a variety ways, my thought is that grapes will behave like all the other species. My suggestion is to remove the plants from the containers and using a machete or large knife, cut off the bottom one inch approx. Then shake the mix off and locate the bottom of the original plug. The objective is to cut off the bottom of what was the original plug at or just slightly above the point where the sides began to taper into the funnel like bottom. If the original plug was only three inches deep, stop there. If the original plug was four or five inches deep, then you can cut off more from the bottom, but leaving roughly a three inch mass of roots. If the grape roots have circled in the old plug container, after cutting off the bottom, take a pair of pruning shears, insert the thinnest part up through the center and make one cut. When growth begins, new roots will grow primarily from the cut faces of the roots and from what is now the shortened length of the plug. The many species I have studied this on have all responded well, with the only losses, the occasional plant that had only one or two roots originating from the cutting or seed and got broken during handling. I also suggest that if you have a greenhouse, you pot these plants up soon in for example, a one gallon RootMaker, and monitor the water closely. Growth should begin relatively soon and the plants will be off and headed for an improved root system.