Light and the greenhouse environment

To the present date, no acceptable form of solar radiation maps for the United States exists for use by horticulturists. The current computer technology, environmental instrumentation and comprehensive weather data that was not readily available in the past has allowed us to develop daily PPF (mol m^-2 d^-1) contour maps per month for each of the contiguous states. PPF transmission to the greenhouse floor is decreased by hanging overhead crops, but the percent reduction of PPF transmission has not been quantified. The number of hanging baskets grown over a bench crop varies tremendously from grower to grower. Currently, there does not exist any method, other than by trial and error, by which growers can determine an optimal basket density for a given location and time of year. Therefore, the percent transmission of outside available PPF that was received at the floor of a greenhouse without overhead containers and with various hanging container arrangements, spacings, colors, and contents was determined. The change of PPF transmission over time, as an overhead crop matured, was also examined. The use of both of these reports may serve to establish a decision support tool for greenhouse light management techniques (e.g. supplemental lighting) at a given location and time of year. This project will also provide general guidelines for designing greenhouses and general strategies for growing and placing hanging baskets in greenhouses. It is also anticipated that the decision support tools generated by this project will provide recommendations for individual growers, which will allow them to make well informed production decisions concerning the optimization of hanging basket production and greenhouse space utilization.