This may mean pulling them outside, removing dead growth and dropped litter, and visually checking each plant. Treat problems immediately. Insect pests and diseases can spread very rapidly in this confined environment. Hand water all plants based on need. Plants at lower light, cooler floor levels could easily get over watered and rot in their cooler micro environment.
All greenhouses have micro environments - be sensitive to that.
Plants should be positioned according to these micro environmental conditions, Water plants in early to mid morning during winter months to avoid cold damp soil during the cooler evenings. During warmer days of summer, watering anytime is ok. Overcrowding can cause carbon dioxide deficiency and stunt growth. These buildups can reduce light significantly. Visually inspect the structure for any problems periodically.