Q.Growing periwinkle
As an Eagle Scout Project, my son is clearing a hillside by out church/school. We are looking to plant a low maintenance ground cover. We originally planned on planting ivy, but the hillside is in the sun 60-70% of the day, and ivy is recommended more for shady areas. Would periwinkle be a good choice? And if so, is it too late in the year to plant it? It is the end of August, and we live in Zone 6. If it is too late, does anyone have a suggestion for something else that we could plant? The hillside covers an are of about 160 feet by 40 feet (the 40 feet is the length of the slope).

Certified GKH Gardening Expert
Periwinkle actually does better in shade, but it may survive in sun. There are some ground covers that are great choices for sunny slopes; here are some examples:
https://www.gardeningknowhow.com/edible/herbs/thyme/growing-creeping-thyme.htm
https://www.gardeningknowhow.com/ornamental/groundcover/creeping-phlox/creeping-phlox-planting.htm
https://www.gardeningknowhow.com/ornamental/flowers/deadnettle/growing-spotted-deadnettle.htm
See the final section in this article for more:
https://www.gardeningknowhow.com/special/xeriscape/drought-tolerant-ground-covers.htm