Title 18 of the New York City Administrative Code covers Parks. There is a reference to a portion of the law that concerns encouraging owners of vacant lots to allow community gardening in vacant lots, but the reference cited points to a section on displaying MIA flags. I am still looking for that legislation and will post it if/when I find it.
Title 56, Chapter 6 of the Rules of the City of New York discusses rules for Green Thumb Gardens. Additional references to community gardens can be found in Title 28 covering gardens licensed by the Department of Housing Preservation and Development.
Meanwhile, New York State laws also discuss community gardens. The State’s Agriculture and Markets Law § 31-H covers the establishment of an office of community gardens in cooperation with the state department of environmental conservation. The law provides for the identification of vacant properties that would be suitable for community garden uses, supporting contact between existing community gardens and groups wishing to start new ones and also for providing grant funding when available. Agriculture and Markets Law § 31-H permits community groups to run gardens on vacant public land provided that they have liability insurance.
Community Gardens Law (New York State Agriculture and Markets Law Article 2-C, Section 31-H and 31-I). (n.d.). Web. Retrieved from http://www.agriculture.ny.gov/cg/CGLaw.html
Title 18 of the New York City Administrative Code. In FindLaw. [Electronic database]. Retrieved from http://codes.lp.findlaw.com/nycode/ADC/18/1
Green Thumb Gardens: Title 56, Chapter 6 of the Rules of the City of New York. (n.d.). Web. Retrieved from http://www.nycgovparks.org/rules/section-6