This spans our complete Portland service area — see our full full Portland metro service area map guide for complete pricing, scope, and scheduling.

Portland’s Urban Forest Is Beautiful — and Brutal on Your Windows

Portland’s urban tree canopy covers approximately 26% of the city’s land area, making it one of the densest urban forests in the US. For homeowners, this is one of Portland’s defining livability assets. For window glass, it is a year-round contamination source that operates differently in different parts of the city depending on which tree species dominate the street canopy overhead.

After 15 years of washing windows in every Portland neighbourhood, I can identify the pollen season, the contamination type, and the window maintenance pattern for a home within seconds of knowing the neighbourhood and the surrounding canopy. Here is that knowledge, neighbourhood by neighbourhood.

Cottonwood — The April Problem Throughout NE and N Portland

Cottonwood trees produce the iconic white cotton fluff in April and May. This cotton is not the pollen itself — it’s the seed carrier — but it behaves like a contaminant: physically lodging in window screens, collecting at the base of window frames, and matting against window surfaces in visible white accumulations.

Highest cottonwood exposure: N. Columbia Boulevard corridor, N. Williams and N. Vancouver Avenue, St. Johns and the Columbia Slough areas, parts of the Cully and Parkrose neighbourhoods. Cottonwood cotton in window screens is among the most thorough track-clogging events of the Portland year.

Elm and London Plane — The Classic Irvington and Hawthorne Pollen

American elm and London plane trees — two of Portland’s most common street tree species — produce fine, adhesive pollen in April and early May. This pollen creates the characteristic yellow-green film on glass that most Portland homeowners associate with spring. It bonds to glass rapidly with moisture and becomes progressively harder to remove without agitation as it dries through warm May days.

Highest elm and London plane exposure: Irvington, Alameda, Hawthorne, Division, Sunnyside, and the boulevard corridors of N. Portland. Homes on blocks with consecutive elm or plane trees experience the heaviest single-week pollen deposits of the Portland year.

Big-Leaf Maple — SE Portland’s May Helicopter Season

Big-leaf maple produces two distinct contamination events: sticky yellow pollen in April-May and the familiar helicopter seeds (samaras) in May-June. The helicopter seeds physically accumulate against window frames and in screen mesh. Decomposing maple seeds produce tannin-rich residue that stains frames and glass edges if left in contact over the wet season.

Highest maple exposure: Sellwood-Moreland, Eastmoreland, Westmoreland, Ladd’s Addition, and homes adjacent to Portland’s many park spaces with mature maple canopy.

Douglas Fir — The Longest Pollen Season in Portland

Douglas fir pollen season runs from March through June, with peak production typically in May. Unlike deciduous tree pollen, fir pollen is produced continuously over a longer period and — most critically — fir trees produce it year-round in a different form: sticky sap droplets, needle debris, and bark fragment fallout that create a continuous contamination source regardless of season.

Homes directly under Douglas fir canopy deal with some form of window contamination every month of the year — which is why these are our most frequent scheduling clients. Highest fir exposure: West Hills, Southwest Portland hills, homes adjacent to Forest Park, Sellwood bluff, and any property with mature firs in or adjacent to the yard.

Oak — The Late Pollen and Tannin Canopy of Laurelhurst and Eastmoreland

Oregon white oak and English oak in Portland produce pollen slightly later than elm and maple (mid-May to mid-June), extending the pollen season for neighbourhoods with significant oak canopy. Oak pollen is coarser than elm or maple pollen and tends to accumulate in visible layers on horizontal glass surfaces (skylights, low-pitch south-facing glass) more than vertical window glass.

The larger impact of oak in Portland is tannin from leaf fall. Oak leaves produce heavy tannin loads when they decompose in gutters and on window ledges through autumn and winter — the brownish staining below window frames in oak-canopy neighbourhoods is almost always oak tannin. Highest oak exposure: Laurelhurst, Eastmoreland, Dunthorpe, and the older residential areas of Lake Oswego.

Neighbourhood Window Maintenance Calendar — Quick Reference