The good news first: routine lawn care — mowing, fertilizing, aeration, seeding, mulch, hedge trimming — never requires a permit, anywhere in the Portland metro. The permit question only comes up around bigger structural changes to a property. (Always confirm specifics for your address; rules vary by city and lot.)
What Typically Doesn't Need a Permit
Lawn maintenance of any kind, planting or removing most ordinary shrubs and small trees, refreshing mulch beds, and routine tree trimming generally fall outside permit requirements across the metro's cities.
What Sometimes Does
Larger changes — removing significant trees (especially in Portland's tree-preservation overlay zones), major grading or drainage work, retaining walls above a certain height, and any changes near a protected wetland or steep-slope zone — can trigger a permit or review depending on the city and the specific lot. If a project goes beyond routine yard maintenance, it's worth a quick check with the local planning department before starting.
HOAs Are a Separate Rulebook
Plenty of neighborhoods across Beaverton, Happy Valley, and the newer subdivisions run through a homeowners' association, and HOAs can have their own rules about lawn appearance, mulch color, hedge height along shared lines, and more — separate from anything the city requires. Check your CC&Rs if you're planning a visible change.
The Simple Version
If it's routine lawn and yard maintenance, don't worry about a permit. If it's a bigger structural or tree-removal project, a quick call to your city's planning office settles it in a few minutes.