killing St Augustine grass requires you to get out the old
weed wacker, and/or a very sharp spade.
this grass spreads in long runners just under the surface of ANYTHING, and will find a way to pop up their heads anywhere you dont want them, and when you try to rip them out, you wind up doing something like pulling a seam...long anchor roots that are part of the lawn itself.
Edging the beds is the key here.
Since this is about the only grass that will grow here, and really is considered a noxious
weed in other areas (and a house
plant some places, honest! ) all you can do is wack away, or chop down and edge.
(
zone 10 b)