Philadelphia has a knotty problem. The city has a large inventory of vacant parcels. Forty-thousand (40,000) in 1990 but "half that" by 2006 according to Maitreyi Roy, a landscape architect with Philadelphia Green.
In 1995, the Pennsylvania Horticultural Society (PHS) Philadelphia Green program began to clean and green the city's vacant lots. Under contract with the City of Philadelphia, PHS manages vacant properties in two ways. One approach is the Vacant Land Stabilization Program whereby some parcels are planted with grass and trees and fenced and another is Community LandCare whereby community groups are paid to clean and mow the remaining vacant lots.
Maitreyi Roy attributes the reduction in Philadelphia's vacant lot inventory to the clean and green strategy: clear the lot, plant grass and trees, and fence it. (In so doing, by 2006, "one-third of that city's vacant lots have become public property, and some have sprouted as parks and other gathering spaces.")
The grass and trees vocabulary is not what one would call "expressive," at least this is argument forwarded by PEG office of landscape + architecture. PEG has not only designed "a cost-effective way to achieve the same aesthetics of care [as PHS's approach] but provide more expressive diversity with lower maintenance," but has implemented its design in two experimental plots -- "Not Garden" and "Not Again." (I first read about PEG's gardens in the April 2010 issue of Landscape Architecture Magazine.)
The Not Garden, as the name suggests, is based on the "intricate geometric patterns" of the Tudor knot garden. In Knot Gardens and Parterres: A history of the Knot Garden and How to Make One Today, Anne Jennings echoes PEG's assertion that a (k)not garden offers "expressive diversity." She writes,
the knot garden can be brashly exuberant, romantically nostalgic or quietly simple and chic.I say that the Not Garden pattern is simple and chic while the Not Again pattern promises to be exuberant. With financial support from PennDesign, PEG staff and PennDesign students "installed two 200 sf prototypes using laser cut geo-textile."
In the fall of 2009, PEG staff and PennDesign students installed the Not Again prototype on a 1,800 square foot lot, also in West Philadelphia. The vegetation is expected to fill in this spring. Additional partners for the Not Again garden include the Redevelopment Authority of the City of Philadelphia and the Urban Tree Connection.
Don't you think PEG's designs would work well on a roof? I am reminded of Martha Schwartz's "Splice Garden" for the Whitehead Institute and Carnegie Mellon's Posner Center roof garden.