Hillsboro, OR Invasive Plant Rules: Prohibited Species (2026)

220, Hillsboro's landscaping chapter under Ordinance No. 6094 and last amended by Ordinance No. 6508 on November 4, 2025, requires Type II and Type III development applications to meet the base zone's minimum landscaping percentage. 500 defines Nuisance Plants as 'Plants which are both invasive and non-native,' further explaining that they 'are identified and listed as a noxious weed by the State of Oregon or listed on Tualatin Soil and Water Conservation District's Weed and Pest Directory,' the same two reference lists the Code uses in its Significant Natural Resources Overlay chapter to police planting near wetlands and riparian corridors.

8 lets a developer count natural existing vegetation toward the required landscaping percentage, but only if that vegetation 'is maintained continuously to remove nuisance plants and to keep the natural vegetation alive,' converting the restriction into an ongoing weeding obligation rather than a one-time planting choice. 7 separately encourages, and can require, drought-tolerant species where irrigation is unavailable. Applicability is narrower than a citywide ban: Subsection B limits the entire landscaping section, nuisance-plant prohibition included, to Type II and Type III development on sites where the base zone requires landscaping, and expressly exempts single detached dwellings and middle housing (the duplex-through-fourplex and cottage-cluster housing types Oregon's 2019 HB 2001 requires Hillsboro to allow in most residential zones).

A homeowner's own yard is therefore not policed by this section; the rule targets landscaping plans submitted for commercial, industrial, institutional and multi-dwelling projects reviewed by the Planning Division.