Two rivers, one dry summer

Hydroseeding in Portland, OR

Rain from fall through spring, very little in July and August, and hills on the west side.

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No-cost site visit, then a quote in writing
Seeding planned around the Willamette Valley rain calendar
Silt fence and stabilization installed to your approved erosion plan

How Portland's Weather and Hills Shape a Seeding Job

Hydroseeding in Portland is mostly a calendar problem. The airport's 1991-2020 normals show about 36.9 inches of precipitation a year, yet July and August average only about half an inch each, while November and December each bring well over five inches. A slurry of seed, mulch and tackifier sprayed in late summer depends on a hose; the same slurry sprayed in December can sit cold and wet for weeks before it sprouts.

West Hills versus the flats

Downtown and much of the east side are fairly flat, but the Tualatin Mountains, known locally as the West Hills, run through the northwest and southwest parts of the city. Plain hydromulch is rarely enough on those slopes; we usually spray a bonded fiber matrix or pin down blankets, because one winter storm can move bare soil downhill before roots hold it.

The soil under the hills

The Cascade soil series was first described near Skyline Boulevard, about 7 miles northwest of downtown. USDA describes it as silt loam over a dense fragipan, with a perched water table over that pan in winter and slopes from 3 to 60 percent. Where a lot has a profile like that, we pay attention to where water will sit and shape the grade so runoff leaves the lawn instead of ponding on it.

Cinder cones and landslide-prone ground

Portland sits on the Boring Lava Field, which has at least 32 cinder cones, Mount Tabor among them. A 2014 report flagged more than 7,000 locations in the area as high risk for landslides and liquefaction in a major earthquake, including much of the west side. We are not geotechnical engineers, so on a steep or unstable lot we work from the engineer's plan and handle the seeding, silt fence and slope cover.

What usually makes sense here

Fall seeding for new lawns, once the rains come back
Spring seeding with a plan for summer watering
Silt fence and inlet protection on infill sites that drain to the street
Lawn repair and overseeding on older east side lots

Tell us the address and what the ground looks like now. Get a free estimate or call (971) 588-2069.

Portland Ground and Weather Notes

Dry midsummer. PDX normals (1991-2020) average 0.51 in of rain in July and 0.54 in in August, against 5.77 in in December.
West Hills. The Tualatin Mountains, called the West Hills, rise through the northwest and southwest of the city; Council Crest Park is at 1,073 ft.
Cascade silt loam. The Cascade series, typed near Skyline Blvd, has a fragipan with a perched winter water table, on slopes of 3 to 60 percent.
Volcanic field. The city lies on the Boring Lava Field, which has at least 32 cinder cones such as Mount Tabor.

Wet-Season Erosion Control in Portland, OR

Our Services in Portland, OR

Portland Questions

Can I hydroseed a Portland lawn in July?

You can, but July and August average about half an inch of rain each, so the seed lives on irrigation. We give you a watering schedule before we spray.

Is a West Hills slope too steep for hydroseed?

Usually not. Steeper banks get a heavier bonded fiber matrix or a blanket, and very steep or unstable ground should have an engineer's plan first.

Why does water sit on my lawn all winter?

Some local soils have a dense layer a couple of feet down that holds a perched water table in winter. Grading the surface so water runs off, and sometimes a drain trench, helps more than more seed.

Do you install silt fence on Portland infill lots?

Yes. We set silt fence and inlet protection where the site drains toward a street or storm inlet, then seed the disturbed ground when the work is done.

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Free site visits across Portland, east side and west.

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