I had this issue with my pink primrose! the grass just took over! pulling it was a waist of time. Then I found some spray called Grass Getter. I thought what the heck I am going to give it a try! I had nothing to lose because my only option was to kill the whole bed and start over. It was pricey! But it only took 1 ounce of concentrate and one ounce of crop oil to a gallon of water. I was stunned at how great it worked. The plants never missed a bet but the grass slowly died out.
Don't get me wrong here! I do not use killing spray's unless I have tried every other option. This was one of
those times. I ordered it on line! It was $19.95 for 1 pint
the crop oil I got at the farm store cheep. I have now used it for 3 years! The same bottle. It was a blessing that I found it. Good by Grass in my flowers from now on.