2007 Annual Report 1a.Objectives (from AD-416) The objective of this research project is to more fully evaluate and understand the quality of composts available in the region that may be suitable as partial substitutes for soil-less media, and which result in superior quality of container plants. 1b.Approach (from AD-416) To collaborate in research and testing of growing media, visits to nursery's and tabulating of nursery results, collaboration with outreach and information gathering sessions to nurseries. 3.Progress Report This report documents research conducted under a Specific Cooperative Agreement between ARS and Woods End Research Laboratory. Additional details of the research can be found in the report for the parent project 3607-21000-011-00D Develop Improved Technologies for Soilless Greenhouse Plant Production to Minimize Water, Labor, Agrochemical Inputs and Environmental Impacts. As part of the soilless media and hydroponics project at the Greenhouse Production Research Group, pH sensitive geranium cultivars will be grown in various compost potting mixes with different buffering potentials. With color change, media pH as an index, C/N analysis and ICP analysis, a test index will result to aid growers in making sound decisions based on dynamic pH properties of compost blends. Compost analyses methodologies have been compared between Woods End Laboratory (Maine) and USDA, ARS, ATRU, Toledo. Work is planned in conjunction with Dr. Paul Nelson’s group at NC State University involving reciprocal research and additional planning sessions. Research results were presented at meetings of the Maumee Valley Growers in Northwest Ohio. Trade shows of the OFA and Ohio Nursery and Landscape Association, respectively, were used to convey experimental results to stakeholders. The project was monitored through periodic reports and research meetings.