The greening of vacant lots can reduce self-reported feelings of depression in adults. In a Philadelphia study of 324 participants living in an area where 110 vacant lots received clean-up and greening interventions, the number of participants self-reporting feelings of depression decreased by 41.5% after vacant lot greening.
South, Eugenia C., Bernadette C. Hohl, Michelle C. Kondo, John M. MacDonald, and Charles C. Branas. (2018). Effect of Greening Vacant Land on Mental Health of Community-Dwelling Adults: A Cluster Randomized Trial. JAMA Netw Open 1(3):e180298. https://doi.org/10.1001/jamanetworkopen.2018.0298