Yellow sunflower in close up

sunflower in the garden The sunflower is a cultivated annual plant with roots up to 2 metres deep. It is very photosynthesis-active; a large plant binds the carbon dioxide present in a space of 100 cubic metres per day. However, the plants are very light-dependent, i.e. the net photosynthesis rate is in direct proportion to the logarithm of the light intensity, which is why even slightly less sunlit plants remain much smaller. It is a typical plant of warm locations, i.e. it is a warmth germinator, it has its maximum growth at 20 degrees Celsius and its cotyledons fold up at night.