Traditionally and correctly considered ideal evergreen ground cover for shade, dry or not. The periwinkles are also prolific flowering plants in the spring, especially the V. minor forms. The caveat is that they can spread over time and become difficult to eradicate once they are in amongst other plants. We find a trim over not too long after flowering helps keep them neat and tidy and allows the flowers to be seen the following spring. Don't be too timid, just shear them down to the ground, growth will soon reappear.