What says?
The only method I have found that works to control Quack Grass is to dig out the rhizomes. That does mean diging the Iris rhizomes and gently removing the Quack Grass rhizomes but it also only need to be done when the Iris rhizomes need to be dug up, about every 5 years.
Apparently Grass Getter requires that you purchase another product, ie. spend even more money, to help the product do its job. You cannot use vegetable oil with Grass Getter because Herbicide Helper is a surfactant, something that reduces surface tension and helps some penetrate something better.

This post was edited by kimmsr on Fri, Apr 5, 13 at 7:40