SURE, tightrope walkers and acrobats once perfected their balance in the vacant lot beside the University of the Arts on Broad Street near Pine.

But usually, the gravelly lot stands empty, garnering nary a glance from passers-by.

That will change today, when the Pennsylvania Horticultural Society officially opens its new pop-up garden, where visitors can watch artists perform, enjoy some brews and food from a beer garden and otherwise relax amid lush plantings. All sorts of art will be on display, including dance, theater, live music, photography, sculpture, design and other visual art (but, sadly, not the tightrope walkers and acrobats, who were Philadelphia International Festival of the Arts performers).

The garden, the third since the PHS launched its pop-up garden program in 2011, serves to raise awareness about Philly's many vacant lots and how development could improve them, PHS spokesman Alan Jaffe said. Its theme: "Lifting Up Our Landscape."

"The idea is to improve our urban landscape," Jaffe said. "We've got so many empty lots, and we can do a lot more with them; we can turn them into beautiful spots, even if it's just temporary."

Two previous PHS pop-up gardens - at 20th and Market in 2011 and on Walnut near 19th last year - drew more than 6,000 visitors each, Jaffe said. The first, which included a vegetable garden with produce given to needy families, also won notice in an international design contest, Jaffe added.

The pop-up program grew out of the PHS' land-care program, in which workers clean and green abandoned lots throughout the city in an effort to beat blight and spur development, Jaffe said.

Leaders from the city, PHS and the University of the Arts will mark the garden's opening with a celebration at 11:30 a.m. today.

The garden, which will be in place through October, will be open 11 a.m. to 2 p.m. Mondays through Fridays, without beer-garden service. The park and beer garden will be open 5 to 10 p.m. Mondays through Thursdays, 1 to 11 p.m. Fridays and Saturdays and noon to 10 p.m. Sundays.

Sponsors and partners include Chipotle Mexican Grill, the Hankin Group, Grant Thornton, Four Corners Management, Groundswell Design Group, Broad Street Ministry, Mark Cook Landscape & Contracting, the Philadelphia International Festival of the Arts and Shearon Environmental.