I wondered because we have 24 garden rows that we rotate and my son planted first one, then a second, then a third row, keeping the previous rows growing and just cutting it once or twice a year. After third year his plan was to plant a fourth row and plow under the first row and then keep on a regular rotation. Originally it was for improving the soil. Maybe it still is, I dunno. But I think he's gotten into other green manures and grains that he's plowed up other areas for so I think he's taking it out of the garden. Not sure. I had no idea it last for several years. Neighbor told us it wouldn't work in the south, but it has!
