Now that I've got all my borders done, I'd like to find a flowering groundcover to fill in the spaces and squeeze out the weeds to some degree. I'm not a big fan of the mulch or rocks showing in between plants and would like the space full. Vinca looks like a good pick, but I have a lot of plants which die back to the ground in winter (Mexican bush sage, lantana, milkweed, hibiscus) here in Fort Worth. Would the vinca make too tight of a mat so that those plants would not get enough sun to come back next season? Or would the vinca actually choke out the existing plants?