NEW YORK — The lemon: An empty Manhattan lot surrounded by beat-up chain-link fencing.
The lemonade: An urban oasis with wildflowers, wooden benches and sculptures in the middle of Manhattan.
The economic downturn has littered the nation's cities with soured real estate developments -- empty lots or partly built projects that were abandoned when funding dried up. Now architects, developers and urban planner are trying to sweeten the situation with projects like LentSpace park in downtown Manhattan.
The park sits at one end of Canal Street in a neighborhood choked by traffic and commerce. Surrounded by wooden walls, the park provides a quiet spot in a part of the city that is short on them.
"This came out of thinking about how you can make the most of this 'in-the-meantime' situation," said Georgeen Theodore, an architect at the firm that designed LentSpace.
Stalled and abandoned construction sites are among the most visible scars of a downturn that ravaged the commercial and residential real estate markets. In New York City alone, 709 projects are idle, up from 398 last summer, according to a list kept by the city.
The sites often attract vandals and squatters and have become commercial dead zones that tend to scare off further development.
"It really changes the streetscape from what was a quite nice neighborhood place to something that feels like a giant wasteland for half a block," said Brad Lander, a professor of urban planning and a New York City Council member, who has set up a website mapping stalled sites in his district.
Lander introduced legislation to levy harsh fines against developers who allow their properties to be taken over by urban detritus and ponds of rainwater. His hope is that the city will be able to nudge property owners to make productive use of the land.
Lander pushed one developer in his own district to turn an unsightly vacant lot into a sculpture garden, but that project was scuttled when the owner accepted an offer to turn it into a parking lot.
In Seattle, the city's planning commission held a competition called Holding Patterns over the summer seeking ideas for vacant project sites. From among the 83 entrants, the commission chose 13 winners, including proposals for a street hockey rink, a temporary theater space and an installation of lights and white curtains that give a touch of whimsy to half-finished buildings. That project, called Sail Away, has already drawn a few interested developers who are helping the artist raise money to carry it out.
The Boston Globe put out a call for architectural projects that could spruce up eyesores like the half-demolished department store that sits on the edge of the storied Boston Commons.
And in San Francisco, urban gardens and retail stores are blossoming along a four-block stretch of empty lots created when an earthquake-damaged section of the 101 Freeway was torn down.
The city was gearing up to sell the properties to apartment developers when the recession hit. The land, on Octavia Boulevard just a few blocks from the Mission District, initially sat vacant and began attracting vagrants and addicts.
The city responded by lending one plot to a community group to convert into an urban garden, the Hayes Valley Farm. Volunteers now gather there Thursdays and Sundays to plant and hoe.
That experiment was such a success that the city recently leased a few adjoining sites for a temporary beer garden and a few small cafes and shops. Those businesses will be inside shipping containers that are being trucked in and altered.
"We are getting a revenue stream, and the neighborhood is getting some really cool stuff on what used to be a vacant lot," says Ken Rich, who oversees the area for the San Francisco Office of Economic and Workforce Development.
The movement is still in its infancy, and there are plenty of obstacles. Perhaps the biggest is persuading cash-strapped developers to pay for temporary alterations and liability insurance.
"When some of these ideas came up, the developers said, 'Listen, that costs money. Wouldn't the money be better spent on actually developing the original project?' " said Susan Elsbree, a spokeswoman for Boston's redevelopment authority.
In San Francisco, the mayor's office has introduced legislation that would give developers incentives such as zoning benefits and guaranteed future construction permits if they make use of the land now.
The LentSpace project, which recently closed for the winter, was funded by $1 million in contributions collected by the Lower Manhattan Cultural Council. The council has also pushed developers to turn unused office space into studios for struggling artists.
A New York firm has come up with a more market-friendly answer to the money problem in the form of a temporary, iceberg-inspired structure that can be quickly erected on empty construction sites using a steel frame and the white gauzy material that wrapped Beijing's Olympic Stadium.