The Japanese knotweed on Philadelphia’s vacant lots can grow 10 feet high and thick enough to hide a rusty trailer. Over the last decade, the Pennsylvania Horticultural Society (PHS) has hacked through the overgrowth in thousands of these lots, replacing dumped tires and mattresses with a tended lawn, a couple of trees, and a tidy wooden fence. The spruced-up open spaces end up making whole neighborhoods safer and healthier. “The purpose of the greening program was really to enhance property val…

To read this article and start a full year of unlimited online access, subscribe now!

Already a subscriber?

Need to register for your premium online access,
which is included with your paid subscription?