Why do botanical gardens use greenhouses to grow tropical plants?

Botanical gardens utilize greenhouses to grow tropical plants primarily to provide a controlled environment that mimics the specific temperature and humidity requirements these species need to survive, especially in temperate climates where winters are cold.123

Many tropical plants are frost-tender and cannot survive the low temperatures found in temperate regions. By using a hothouse—a type of greenhouse maintained at higher temperatures—botanical gardens can protect these plants from freezing, allowing them to thrive and even flower throughout the winter.41

Beyond temperature regulation, these structures allow for the management of relative humidity and protection from wind, creating a stable microclimate that supports the growth of diverse tropical flora, such as orchids, ferns, and palms, which would otherwise perish in the local outdoor environment.123