Round -up does nothing to kill some yard weeds and an aggressive bed of mint - I've heard that using a weed killer called Cornerstone in conjunction with something called Top Surf 80 will get rid of these interlopers. Do you agree? Also will it kill surrounding bushes from being absorbed through the soil? will I be able to plant flowers in the same soil that the offending weeds were killed?
I will send you two links to follow. One is for Cornerstone (which contains Glyphosate, the chemical in Roundup)
The other link is for Top Surf 80, which is a surfactant that makes the chemical stick to the leaves better.
Let me know if you need more information. Always read label directions.
Jefferson Co Extension