Philadelphia County, PA Invasive Plant Rules: Prohibited Species (2026)

Pennsylvania's approach to invasive plant regulation is primarily through the Department of Conservation and Natural Resources (DCNR) and the Department of Agriculture, which maintain advisory lists of invasive and noxious plants. The Pennsylvania Noxious Weed Control Law targets agricultural weeds (such as Canada thistle, bull thistle, and multiflora rose) but has limited applicability to urban residential settings. The PA DCNR maintains a list of invasive plants that affect Pennsylvania ecosystems, including Japanese knotweed, tree of heaven (Ailanthus altissima), English ivy, porcelain berry, and lesser celandine. Japanese knotweed is particularly problematic in Philadelphia, growing aggressively along waterways, vacant lots, and building foundations. The Philadelphia Code's landscaping provisions (Title 14, Section 14-705) require vegetation to be maintained and not create nuisance conditions. The Philadelphia Parks and Recreation Department manages invasive species on public lands. Community-based organizations like the Schuylkill Center for Environmental Education coordinate volunteer invasive plant removal efforts across Philadelphia.