A three country effort (U.S., Russia, and Bulgaria) has upgraded the plant growth facilities on the Mir Space Station and used the new facility to grow wheat for 90 days. The Svet plant-growth facility was reactivated and used in an initial experiment as part of the Shuttle/Mir program, August to November, 1995. The Svet system, used first to grow cabbage and radish during a 1990 experiment, was augmented by the addition of a U.S. developed Gas Exchange Measurement System (GEMS) that measures a range of environmental parameters plus transpiration, photosynthesis, and possibly respiration. Environmental parameters include cabin, chamber, root-zones, and leaf temperatures. Light levels, relative humidity, oxygen, and atmospheric pressure are also measured. High-accuracy water-vapor and carbon-dioxide concentrations and differences are measured using specially developed IRGA systems. An upgraded light bank, water control and measurement system, and Svet controller have been added for the 1996 segment of the experiment.The “Greenhouse 2” experiment began August 10, 1995, with seed planting on August 13. Plants grew until the launch of STS-74 in November, at which time they were harvested and dried and returned for analysis along with previously fixed and dried samples. The root module, light bank, and hard drive were also returned for detailed analysis. This paper details the capabilities of the equipment and describes the resulting environmental measurements observed during the 1995 experiment.