I have had Vinca major growing along a fence which was already here, it used to annoy me as it grew from amongst shrubs which the neighbour had planted close to the fence. It isn't deep root and is easy to pull out, it's when they are protected by growing amongst other roots which makes it difficult. It's now growing at the base of a Hawthorn hedge, I pull some out but do like to see the flowers.
Periwinkles are "fairly deep-rooted" (review by [79]). Common periwinkle plants in western Montana exhibited fibrous roots ranging from 1 to 3 inches (3-8 cm) long [96]. Further descriptions of roots were unavailable as of 2009.
1 to 3 inches isn't long, and when growing in leaf litter they come out easily.
Under •BOTANICAL AND ECOLOGICAL CHARACTERISTICS
http://www.fs.fed.us/database/...
