I've used Grass B Gone, and got the best results when it is sprayed while the grass is young and growing. I sprayed some last week, and this week the grass is dying. If you wait until it's mature, it will still kill it slowly. I sprayed some really late in the fall, and the grass was dead by spring. roots all dried up. No harm to irises, or Day lilies, or peonies. I was using it on quack grass.
