2006 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Woods End Research Laboratory, Inc. Additional details of research can be found in the report for the parent CRIS 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, Carbon/Nitrogen analysis and ICP analysis, a test index will result to aid growers in making sound decisions based on dynamic pH properties of compost blends. Work is progressing with reciprocal visits and planning sessions.