Plants do not need in order to grow. We can prove this by sowing a seed on damp cotton wool or blotting paper and putting it in a warm, light position. Plants do,however, need , but not too much, or they will rot. They need to be kept damp. If we do not water them, they will . They also need in order to grow well. If we put a green plant in a dark place and keep it warm and watered, it will continue to grow for some time, but it will lose its green colour (the ). This is because it can no longer make from sunlight. It will initially grow tall because it is searching for light, but eventually it will die. Plants also need warmth to grow. During the winter time, when the temperature drops, trees lose their leaves and become . Evergreen trees and plants may keep their leaves, but they do not grow. When testing to find out what plants need to grow, it is important that our test is . We should only change thing at a time (eg, deprive a plant of water, but give it everything else)