Technical Abstract: High tunnels and other plastic-clad structures are used to extend the harvest season, improve crop quality and yield, and decrease incidence of foliar and fruit diseases. Many publications on high tunnel production have dealt with structure designs, construction techniques and cropping systems, but the possible enhancement of phytonutrient contents or foodborne pathogens when crops are grown in high tunnels or micro-environment variations, application of colored shade cloth and light emitting diodes to affect plants in high tunnels is not well documented. This paper summarizes issues on food safety when manure and raw manure are used for soil amendments, location and plant canopy effects on temperature variations in high tunnels over a growing season, modification of light spectral quality to affect plant growth and quality with colored cloth shading and low-cost light emitting diodes.