Gardening and growing plants in greenhouses is different from growing plants outside as no rain can get inside a greenhouse, so gardeners have to water plants. Also, greenhouses can get very hot from the sun's heat, so gardeners have to make sure that it does not get too hot for the plants. Greenhouses usually have vents that can be opened to let excess heat out. Some greenhouses have electric exhaust fans that automatically turn on if it gets too hot in the greenhouse. A greenhouse is the place for tender plants such as tomatoes, cucumbers, and aubergines.