The cost of running a large greenhouse is partially affected by the levels of light and temperature of plants are provided with plenty of carbon dioxide the grower can get two Crops a year at 20°c and three crops a year at 30°C in their greenhouses. explain why majy growers use 20°c rather than 30°c in their greenhouses in your explanation suggest why many growers are also investigating in insulation systems that can be added and removed electronically