What is a greenhouse used for in agriculture?

A greenhouse is primarily used to create a controlled environment for plants, which significantly extends the growing season. By providing shelter from adverse weather conditions, such as frost and excessive heat, a greenhouse allows plants to thrive in temperatures that might not be suitable for outdoor growth during certain times of the year. This capability enables farmers and gardeners to start planting earlier in the spring and continue growing later into the fall or even winter, depending on the crops and greenhouse management practices.

While growing plants without soil can occur in greenhouses (like hydroponics), the essence of a greenhouse's primary function revolves around extending the growing season by managing temperature, humidity, and light. Other aspects, such as crop rotation, do not directly relate to the mechanisms within a greenhouse but rather pertain to land management practices outside of controlled environments. Thus, focusing on the greenhouse's role in extending the growing season captures its core purpose effectively.