Is it OK to plant English ivy around the base of a cherry tree located on one of our residential streets in Philadelphia?
English ivy is probably not a good option. You would have to monitor it carefully to be sure it didn't climb up the tree, and it forms a dense mat that takes nutrients away from the tree. It also is difficult to keep constrained if it is in a garden bed. You might want to consider perennial vince (periwinkle) that gets a pretty blue flower in the spring.