A glasshouse is a large structure clad in glass (or modern transparent plastics) in which plants are grown under controlled conditions — the commercial-scale version of the greenhouse. By regulating temperature, humidity, light, and carbon dioxide, growers produce tomatoes, cucumbers, peppers, salads, and ornamentals year-round, independent of season and weather, with far higher yields per hectare than open fields. Dutch glasshouse horticulture is the world’s most advanced, exporting vast quantities of fresh produce. The costs are energy and capital: heating glasshouses in winter carries a heavy carbon footprint, driving interest in geothermal heat, waste-heat capture, and LED lighting. Glasshouses also serve science, housing research collections and breeding programs.