| Roundup would be better than tilling: it sprouts from the bits that tilling leaves behind. Get it growing REALLY well and 3-4 inches high - don't mow, pull or cut it back at all. Then spray it with Roundup (diluted according to the package directions), leave it 24-48 hours for the Roundup to hit the roots, then mow it really short. Give it a couple of weeks, and respray what's left and what is resprouting. You will have to patrol with a hand sprayer to get the stragglers. , but that will knock it back. To protect the shrubs and flowers, cover them in newspaper, or sit paper bacs on them while you spray. I use a cardboard shield between the spray and larger plants. | 
