Landscaping Rules in Multnomah County, OR (2026)
3 county-level rules, plus city-specific rules for 2 cities in Multnomah County, Oregon.
Verified from official government sources
Tree Removal & Heritage Trees
In unincorporated Multnomah County's mapped Significant Water Resources (SEC-wr) overlay, no more than half of mature trees over 6 inches DBH may be cut without one-for-one replacement and a county-approved mitigation plan.
Multnomah Co. Riparian Tree Rules
Some RestrictionsMultnomah County Code § 39.5590(C)(4)(b)
Development in areas of dense standing trees shall be designed to minimize the numbers of trees to be cut. No more than 50 percent of mature standing trees (of 6-inch DBH or greater) shall be removed without a one-for-one replacement with comparable species. Replacement trees shall be placed within the riparian corridor or adjacent to it to provide shade and water retention. Size of the replace...
Weed Ordinances
Multnomah County declares uncontrolled or uncultivated weeds, brush or grass a nuisance when they harbor vectors or rodents, spread noxious pollen, create a fire hazard or produce toxins, per County Code § 15.229(A)(7); enforced by the Sheriff and Health Officer.
Multnomah County Weed & Grass Nuisance Rule
Some RestrictionsMultnomah County Code § 15.229(A)(7)
(7) Uncontrolled or uncultivated growth of weeds, brush, or grasses which offer vector or rodent harborage, contribute noxious pollens to the atmosphere, constitute a fire hazard or produce toxins that are harmful to humans, pets, livestock or wildlife. (8) Any explosive or radioactive substance unless the possession is authorized by law. (9) Any vacant building, left unsecured and unattended ...
Native Plants
In land mapped SEC-h for significant wildlife habitat, Multnomah County requires every mitigation planting to be a native species from the Metro Native Plant List. It is not a countywide landscaping rule, and Portland runs its own separate code.
Multnomah County SEC-h Native Plant Mitigation
Some RestrictionsMultnomah County Code § 39.5540(D)(3)(d)(i)-(ii)
(i) All trees, shrubs and ground cover shall be native plants selected from the Metro Native Plant List; (ii) Native trees and shrubs shall be planted at a rate of one (1) tree and one (1) shrub for every 100 square feet of development/disturbance area. Bare ground shall be planted or seeded with perennial native greases or herbs. (iii) All vegetation shall be planted within the mitigation area...
Landscaping Rules by City in Multnomah County
2 cities in Multnomah County have their own landscaping rules rules. Each link goes to that city's dedicated page with code citations.
All Multnomah County ordinances
See every category we cover for Multnomah County: parking, noise, fences, fires, animals, pools, and more.
Multnomah County Ordinance Hub →