Drew Becher

is president of the Pennsylvania Horticultural Society

Philadelphians moved outdoors this summer.

In a city that used to be known for rolling up its sidewalks when the sun set, this summer we had a vibrant, open-air nightlife enhanced by temporary installations - pop-up gardens.

These urban oases seem to work for everyone. They have been created by for-profit, nonprofit, quasi-public, and public-sector organizations, and they have helped once-forlorn sites attract more than 300,000 patrons and boost foot traffic and sales on commercial corridors.

On our eastern riverfront - where the city has tried for decades to redevelop and reconnect with one of our most important natural resources - the quasi-governmental Delaware River Waterfront Corp. built Spruce Street Harbor Park. The summer-fall attraction included floating barges, lily-pad water gardens, a mini-boardwalk, and food from Iron Chef Jose Garces. It was named one of the "World's Best Urban Beaches" by Jetsetter.com.

Philadelphia's Parks and Recreation Department reimagined a former parking lot as the Oval, a monthlong, family-friendly gathering spot of games, good food, and outdoor art at the foot of the Museum of Art.

The nonprofit Pennsylvania Horticultural Society planted its PHS Pop Up Garden near 15th and South Streets, on a vacant lot owned by music legend Kenny Gamble in a burgeoning section of the city often overlooked by out-of-towners and city residents. The lot was transformed into a tropical resort with lush plantings, hammocks, and bright sun umbrellas. The closing party is today, starting at 3 p.m.

PHS sowed the pop-up garden trend in 2011 by transforming a long-neglected vacant lot six blocks from City Hall into a green space that offered a variety of activities through the summer. PHS built raised production beds and harvested fresh veggies for local chefs and for its City Harvest program, which brings healthy food to 1,200 needy families each week during the growing season.

Excellent urban design is key to the success of each pop-up garden - it must be sophisticated and natural, hip and welcoming, hot and cool. The design of PHS's 2011 site was honored with inclusion in the U.S. Exhibition at the Venice Architecture Biennale. Great landscape design has been emphasized in each of its gardens since.

In 2012, PHS popped up across from Rittenhouse Square, on a vacant spot where a movie theater burned down decades ago. The focus was a 56-foot-long table surrounded by a rainbow of chairs, where commuters and community members could bring their lunch and roam through an urban meadow of grasses, flowers, and sculpture. In 2013, PHS was invited by the University of the Arts to activate an empty lot on its Broad Street campus in the heart of the city's performing arts district. PHS brought gorgeous crape myrtles and towering honey locust trees, exotic and native plants, and something new for its gardens: beer and regular evening hours.

More than 28,000 people visited PHS's pop-up garden over the summer of 2013, while previous pop-ups had drawn about 7,000 visitors. This year, PHS has welcomed more than 50,000 guests since early July.

This season, what each pop-up garden around the city had in common was beer (and other adult beverages). But they also shared a mission: Taking underused - or utterly neglected - urban spaces and remaking them into beautiful, exciting destinations. The gardens brought renewed energy and life to the riverfront, the Parkway, and the neighborhoods. And they helped generate a substantial economic boost to surrounding restaurants, bars, and shops, according to local business associations. More than half the businesses reported an increase in sales from the previous year, with some reporting revenue up 30 percent.

Philadelphia has always been a rowhouse city of densely populated neighborhoods, where residents with tiny backyards crave green, open space. It's a city that has seen a 13 percent population increase since 2000, with a particularly significant surge in younger people - the number of residents between 25 and 34 downtown is twice the national average. But the appeal of pop-up gardens crosses demographic lines; they are enjoyed equally by newly arrived millennials, young families, boomers, empty nesters, and longtime residents.

Philadelphia didn't invent outdoor socializing. Italians perfected the piazza, the French made an art of the sidewalk café, and the Germans cultivated the beer garden. But Philly has added its own dimensions to the concept, filling holes in the urban fabric and filling the need of residents and visitors to get out, kick back, and take in summer in the city.