The supply of water in the right quantity and at the best possible time is an important prerequisite for the growth of the vines and is indispensable in photosynthesis. This is done naturally through precipitation (rain), the amount required (depending on the climate, soil type and grape variety) is usually between 500 and 750 millimetres per year. With ideal soil conditions, however, larger amounts of precipitation can also be tolerated. In the Portuguese Vinho Verde region, for example, the amount of precipitation is 1,500 millimetres. In addition to the amount, the timing also plays an important role in the course of the annual vegetation cycle.