I have to say I had 'scary' vinca. I got a pot with a combination of plants for my birthday several years ago, with the variegated vinca as a spiller plant, hanging out of the pot. The pot was placed on a low step near my back garden bed. The vinca grew out of the pot, into the garden bed, rooted and took off. It grew, and grew, and grew. Initially, I thought it was very pretty, as ground cover under my roses and peonies. However, I changed my mind when it grew up and over the roses and peonies, and I constantly had to pull it some of my potted plants where it snuck in from the bottom of the pots.
It took over my L shaped garden bed that had roses, peonies, and lilies. It grew under my Aborvitaes, and started growing over my retaining wall, and showed up in the bed outside of my daylight basement, well away from where the original plant started. Although I like the leaves and the lovely blooms, it proved to be too much in my garden, and it was eradicated this year.
