I have about 10 customers with concrete edging in the landscape beds. It's that curved edging that resembles a curb at the street. Most of them are very happy with string trimming along these concrete landscape curbs. One of them asked me today to cut an edge between the grass and the edging (a gap) so that the St. Augustine wouldn't grow up over the curb between mowing's. I know what she wants, but a stick edger will only chip and crack the edging and a string trimmer won't cut the edge deep enough to keep the St. Augustine away from the edge. I told her that I won't use the stick edger...for obvious reasons... and she doesn't like the finish that the trimmer leaves. I also told her if she wants a nice crisp edge on the landscape beds (that I can maintain to perfection) then she needs to have the concrete curbs removed. She said that she likes the curbing and doesn't want to remove it. Now... this is good customer and I don't want to step on her toes...but I don't think I can give the quality that she wants without the risk of chipping or cracking the curbing. Any suggestions?