Vegetation Goes Vertical

In densely packed cities, green space is often hard to come by. Apartment dwellers who yearn for a whiff of nature resort to potted plants on fire escapes or roof gardens. But what if you could create forest with trees that stack on top of each other? A forest that grew up instead of out?

In Milan, Italy’s fashion mecca, architects are constructing a two-tower apartment complex sheathed in vegetation. The towers, which should be completed this year, will be able to hold 730 trees, 5,000 shrubs, and 11,000 low-growing plants—the equivalent of roughly two and half acres of forest.

Bosco Verticale, or “vertical forest”, merges traditional building materials like stone and concrete with “something that is related to the natural,” says Gianandrea Barreca, an architect involved in the project. It’s about more than just aesthetics. The trees and shrubs will provide shade and buffer the building against noise and dust, Barreca says. Stefano Boeri, the project’s mastermind, has said that adding all that green will increase construction costs by just 5%.

MVRDV’s Torre Huerta

Forested skyscrapers can also help preserve a region’s heritage. As the metropolis of Valencia, on Spain’s eastern coast, sprawls outward, new developments devour the orchards and fields that once surrounded the city. The Dutch firm MVRDV Architects has developed plans for a 21-story building — Torre Huerta — dotted with balconies that protrude like gangplanks. Each balcony would hold trees salvaged from the doomed orchards. Residents could pick their own oranges and lemons.

The idea of high-rise cultivation isn’t new. Dickson Despommier, a microbiologist at Columbia University, has been talking about vertical farms for more than a decade. But the idea finally seems to be gaining traction. A commercial-scale vertical farm opened last year on the island nation of Singapore, a country that imports more than 90% of its food. In Sweden, Plantagon began constructing its first vertical farm this year. There vegetables will grow in pots as they travel down an enormous spiral ramp inside the greenhouse. “There is no plant in the world that you can’t grow indoors,” Despommier says, which means vertical farms of the future could also produce biofuels, medicines, or vaccines.

Growing celery in a skyscraper may seem a bit unnatural, but so is growing celery in a field, Despommier argues. “The act of farming is totally unnatural,” he argues. “The moment you start to replace everything with just one thing — like wheat or rice or corn or lettuce — you create problems.” And moving trees to balconies comes with its own set of problems. Despommier points out that trees are hefty. They’re also high maintenance. In a built environment, they need water and soil and tending. Moreover, an apartment building, no matter how leafy, is not a forest — it’s meant to house humans, not animals. “I can think of far better things we should be putting our time and effort into,” writes Tim De Chant on the blog Per Square Mile, “like preserving places that already have trees growing on them or planting more on streets that need them.”

But with cities expanding and new developments replacing natural habitats, even imperfect urban greenery seems preferable to a concrete jungle. Boeri envisions the towers under construction as a small part of a larger project called BioMilan, which aims to strike “a new balance between the urban sphere, rural areas, and the natural world.”

Slideshow: Vertical Forests