Question
Hello, I have a hillside planted with vinca. A fellow who did yard care for me a couple years ago sprayed the hillside with something that killed the grass, weeds, and morning glory, but left the vinca untouched. It was like a miracle! Do you know what this product is? I didn't have the sense at the time to ask him what he used and haven't been able to track him down. Thanks!

Answer
Hi Marcia,
Thanx for your question.  I cannot tell you what the spray is because I am not familiar with it.  I do know that there are other applications in the form of dry powders or beads that is called Preen.  Preen stops seeds from germinating whether good or bad seed but does not harm established plants, even seedlings.  I hope this helps.
Tom