I purchased grass-be-gone also but it did not work on my St. Augustine grass. If I get desperate I will use a sponge or paint brush and dab RU on the weeds or grass that is imposing. If you use vinegar or round-up you cannot risk the spray being carried by the wind, also you do not want any to go into the soil so the paint brush is a good way to kill one plant and leave the neighbors untouched. Even a small drift will ruin the daylilies (deform) or kill them.
Ann,
(sending you a few acorns)
