Wash the cups with water after drinking soy milk, and then use the water from washing the cups to pour into the pots, without having to go through fermentation. Both expired soy milk and fresh soy milk can be poured into flowers. However, it is important to note that you should never pour soymilk powder into a flowerpot, nor should you pour soymilk directly into a flowerpot; it must be diluted, with a concentration of about 3%. In the growing season can be watered once a week, while dormant once a month is enough, but note that the concentration can not be too large, the number of times should not be too much. Do not spend money to wash the bottle water or expired soybean milk, that is, waste to treasure, environmental protection and energy saving, you can improve the soil, the plant is not toxic negative effects, it is really a multi-purpose.