Final answer:
A disadvantage of the even span greenhouse is limited space for vertical growth.
Step-by-step explanation:
A disadvantage of the even span greenhouse is limited space for vertical growth. Even span greenhouses are designed with a gable roof and a uniform height throughout, which restricts the height of the plants that can be grown inside. This limits vertical growth and can be challenging for plants that naturally grow tall. For example, tall crops like tomatoes or corn may not have sufficient space to reach their full height, which can result in stunted growth or reduced yield. In contrast, a greenhouse with a higher clearance or a sloping roof, such as a gothic or sawtooth greenhouse, allows for better utilization of vertical space and can accommodate taller plants.