In order to identify the best practices and guidelines for the conservation of contemporary artworks, innovative approaches are needed, based on a monitoring campaign to assess the rate of alteration/decay of the objects placed outdoors. In this project, which is still in its first stage, the evolution in time of characteristic parameters is being used to establish thresholds for maintenance or restoration of three installations in the monumental garden of the “Fattoria di Celle”, located in Santomato (Pistoia, Italy). This garden hosts the Gori collection of 43 site-specific artworks created by contemporary artists. The three installations selected have different material compositions: bronze, stone and mortar painted with acrylic colors and glass. Each installation had its own conservation problems related to the constituent materials, together with the important impact of outdoor exposure and location. After a preliminary investigation, the major issues and risks for each artwork were identified and the monitoring campaign was started. Portable diagnostic tools and micro-sampling were used to monitor the parameters chosen. One year into the campaign, the preliminary diagnostic documentation has been realized, mainly for the bronze artistic object. Furthermore, the initial guidelines for monitoring campaigns have been defined.