Big makeover to sprout 18-stories-tall garden

PORTLAND – They haven’t figured out yet how to get the pruning done, but architects and federal officials plan one of the world’s most extensive vertical gardens in downtown Portland – what amounts to a series of 250-foot-tall trellises designed to shade the west side of an 18-story office building.

It is not a new idea to use greenery vertically as “living architecture,” running plants up the sides of a building to keep it cool.

But even in a city with a reputation for rain-fed greenery as well as for green architecture, the wall of the Edith Green-Wendell Wyatt Federal Building would stand out.

The architects’ plans call for seven vertical “vegetated fins” to jut at acute angles. The fins would be the metal framework for planters and the greenery sprouting from them.

The west wall is 150 feet long, making the expanse to be shaded about three-quarters the size of an NFL field, minus end zones.

The work is part of a $135 million remodeling, with most of the money from federal stimulus funds. It is the largest single stimulus project announced so far in Oregon.

Architect Don Eggleston’s firm, SERA Architects, is working on some questions that weekend gardeners never have to figure out: what plants will grow readily at more than 200 feet in the air and how to water, fertilize, weed and prune at that height.

Rainwater collected on the roof, supplemented by city water, will be piped for irrigating the green wall, he said.

The building is a modernist, International-style high-rise completed in 1975 and named for two U.S. representatives from northwest Oregon. Across a city park, it is face to face with City Hall.

It hasn’t aged well. Its precast concrete facade has settled, opening gaps around its single-pane windows, and it’s leaking air and water, said Kevin Kampschroer, the General Services Administration official in charge of the greening of federal buildings.

“It’s not structurally unsound, but it’s not going to get any better,” said Kampschroer.

So, off will come the facade, and out will come some of the building’s guts.

Construction is expected to take 30 to 40 months. The building’s three other walls will have less striking treatments: shades on the south and east walls and windows that drink in the indirect north light.

The building’s roof will stick out about 20 feet and look like a giant mortarboard. The overhang is designed for shade.

But attention is likely to turn quickly to the plans for a greened-up west wall.

Sean Hogan, writer, nursery owner and garden designer who worked on a green wall several years ago for the parking garage at Portland’s airport, said irrigation and plant selection will be critical to keeping a green wall green in Portland’s summers.

Despite its reputation as drizzly, the city’s climate is Mediterranean, with warm to hot temperatures from late spring to early fall and little rainfall.

“Trust me, it will be a challenge,” said Randy Gragg, former architecture critic for the Oregonian newspaper and editor of Portland Monthly magazine. “It will get baked, absolutely.”