Aligning Impact for Healthy Communities: Q&A with the Pennsylvania Horticultural Society

2015 Update: Greening Urban Lots Delivers Additional Health Impact

In addition to the findings discussed below regarding greened vacant lots lowering crime and increasing housing wealth, a new study from the Perelman School of Medicine at the University of Pennsylvania found that the improved lots may also be associated with biological reductions in stress. To learn more, see this Penn Almanac story or the full research article.  And to provide support, see high impact opportunities listed below!


For the past several months, our team has been developing an online opportunity map for U.S. food funders. The purpose of the map is to clarify the types of food-related impacts sought by donors, identify opportunities for partnership and leverage, and offer examples of ways donors can and have created change.

Three Sources of EvidenceTo ensure that our donor guidance is informed by the best available evidence and actionable to donors now, we’ve been sharing and vetting our work with dozens of researchers, practitioners, and experts focused on food system impacts.

At the 2013 Feeding Cities conference and from subsequent conversations, we learned from Drew Becher, President of the Pennsylvania Horticultural Society (PHS), and Bob Grossmann, PHS Senior Director of Vacant Land, about an interesting approach to achieving multiple food-related impacts, including improvements in health, environmental sustainability, and community development. The following is a brief Q&A with Bob Grossmann and PHS on some key details regarding their Vacant Land initiatives.

For Donors Who Care About Impact

For donors interested in urban land use – or reuse – there may be alignment across several impacts, such as improved community benefits through property values and safety, environmental benefits regarding soil quality, runoff and resource use, and health impacts regarding the provision of healthy food. How can donors identify high quality programs across the country?

BG/PHS: Land reuse programs are nationwide, with many organizations focused on it. Many people think about high profile urban areas, like Detroit, but  places like Phoenix also have tremendous amounts of vacant land. While their “cleaning and greening” process is different because of the climate, the concept is  the same, as is the importance to the neighborhood. You can find examples at Centers for Community Progress.

Donors can think about how they can support pilot programs or improve procedures and protocols so their local organizations can better scale to deliver real and lasting impact to the community.

The Model: Cleaning and Greening

One evidence-based model for land reuse that you described was “cleaning and greening”. What is the model, and what evidence supports that it’s working?

BG/PHS: “Cleaning and greening” a vacant lot, coupled with low-cost maintenance, is one intervention that has been extremely effective in Philadelphia and other cities nationwide. This approach can involve clearing trash and debris, planting grass and trees, and installing a simple wooden fence to signal that the space is being cared for. At PHS, our LandCare Program is seen as an international model for post-industrial cities seeking to clean, green, stabilize, and ultimately reduce their inventory of vacant lots.

We know that these vacant lots destabilize neighborhoods, become a haven for illegal activity, and create a downward spiral for abandonment and disinvestment. We also know that, often in partnership with city government —the frequent owners of these lots—this simple landscape design can have dramatic results. For example:

  • A ten-year study, published in the American Journal of Epidemiology that looked at over 7.8 million square feet greened across four neighborhoods in Philadelphia, found reductions in gun crimes and vandalism, and improvements in safety and other health benefits.
  • Another study by the National Vacant Properties Campaign found that house sales prices increased as much as 30 percent when homes were located near vacant lots that had been “cleaned and greened.”
  • In related pieces by additional University of Pennsylvania researchers, including a testimonial to the Philadelphia City Council, Dr. Kevin Gillen said, “Following conversion of a vacant lot, the median gain in housing wealth to the affected households was estimated to be approximately $35,000 … every dollar spent on ‘cleaning and greening’ generates an additional $224 in housing wealth and $7.43 in property tax revenues.”

Coordinating Efforts for Land Rehabilitation and Agriculture

To be clear, this reuse model is very different from the reuse in urban areas that involves significant reconditioning and rehabilitation to make the soil safe for urban agriculture. For you, how do those efforts fit together, or do they?

BG/PHS: Because of the significant rehabilitation costs for nearly all vacant urban land (contaminated from a range of things, over the years), most urban gardening needs to be above ground in boxes. So often those projects can be a second stage to land care efforts or on parcels/properties nearby, due to the high availability of vacant land within many communities.

But community gardening is another proven way to improve vacant spaces and transform them from liabilities into community assets. For example, the PHS Garden Tenders and City Harvest programs often work in tandem with the LandCare program and achieve many similar community impacts, while also producing millions of pounds of produce each year. That produce stays in the neighborhood and plays a huge role in the food security equation in Philadelphia.

We try to identify land within neighborhoods just beyond active real estate, by considering the following factors:

  • We look for sites where there are other strong community partners and where other types of reinvestment is already happening to aggregate the maximum visual impact and achieve economies of scale.
  • We select sites that are along transit corridors or around schools or other areas that would be important for health, safety, or economic reasons. With these conditions, a strong network of partners, including the government, can achieve these results.

Image source: PHS

“Bang for Buck”: A Cost Example

Since we’re always thinking “bang for buck”, what’s the cost of the PHS LandCare program? It sounds like it could be quite expensive and varied, depending on the neighborhood.  

BG/PHS: No, actually the costs are amazingly consistent. The installation cost (i.e., “cleaning and greening”) costs about $1 per square foot, by using bulk purchasing of materials, like trees and seeds, and competitive bids for contractors. There are also low, ongoing maintenance costs for upkeep during the warmer months (about $10 per visit), which is critical to having the desired long-term impact within the community.

So, for example, the average lot in Philadelphia may take $1,000 to clean and green, and $140/year to maintain ongoing. At these prices and based on this evidence, we’ve used PHS LandCare, in collaboration with the City of Philadelphia, to provide and maintain interim landscape treatments to over 6,000 properties in key transitional neighborhoods. And, to date, approximately 15 percent of PHS LandCare properties have been sold and developed.


Talk To Us

So, as we continue to have discussions that help us build the Center’s opportunity map for donors in the food space, we thought we’d share one practitioner’s perspective about land reuse. As always, we’d love to hear your perspective. Please let us know if there are additional evidence-based strategies or organizations that should be on our radar!