Plants require certain chemicals and nutrients to grow and develop. Water can provide these essentials to plants effectively and efficiently. Milk has useful properties for protection but cannot help plants develop at any rate of speed.
Effects of Water
Water provides three essential items to plants; hydration, hydrogen and oxygen. Plants use this during photosynthesis along with carbon dioxide and sunlight to produce food and energy.
Effects of Milk
Milk has varying degrees of water in it along with sugars, carbohydrates and lactose; the latter elements cannot be readily utilized by plants. The lactose and sugars attract bacteria, which then changes the composition of the milk to a more acidic liquid, creating altered pH and the potential for pathogens and mold to develop.
Plants watered solely with milk have limited ability to absorb nutrients from the soil or from the water within the milk because of various factors, including the milk's viscosity and slow chemical breakdown. The pores of the plants have limited or no ability to absorb needed nutrients, causing the plant to wilt or die within days or weeks.
Milk has various protective properties, such as altering pH levels of leaves to prevent disease attack. Milk cannot aid in plant development. It must be used in a severely diluted form with water to be beneficial. It should not be used alone.