Sunlight

• Exposure to the sun is necessary for plants to grow and thrive. Using energy from sunlight, the plant combines water from rainfall or watering, carbon dioxide from the air around it and nutrients from its growing medium to create sugars, which it uses for growth. This process, known as photosynthesis, is the starting point for the other four things that a plant needs to survive.
  
  

Water

• Water, fundamental to all known life, is essential to plant growth in several different ways. When combined with carbon dioxide, the molecules in water are converted to oxygen and sugar through photosynthesis. It also aids in a plant's ability to absorb nutrients from its growing medium by dissolving the nutrients, allowing them to make their way into the body of the plant. As water enters the roots and works through the plant body, eventually evaporating out of the stems and leaves, the water helps to cool the plant and allows the plant to absorb carbon dioxide from the air around it.
  
  

Carbon Dioxide

• Carbon dioxide, which plants use to create the sugar needed for growth, is absorbed from the air around the plant. Living creatures that breathe oxygen expel this chemical compound; a person, for example, inhales oxygen and exhales carbon dioxide. The plant absorbs the carbon dioxide through its leaves and stems as it is evaporating water, and converts the compound created when carbon dioxide and water join into sugar by using energy from sunlight. It then expels oxygen, starting the cycle over again.
  
  

Growing Medium

• All plants require some sort of medium in order to grow, with soil being the most common. Plants can also grow in open air, attaching their roots to surrounding structures or other plants, as well as in water. Plants absorb nutrients from their growing medium to support their growth and aid in the process of photosynthesis. The growing medium also allows for a plant to develop a root system, which holds it in place against outside forces.
  
  

Nutrients

• Plants require several different nutrients in order to support the process of photosynthesis and to utilize the sugars it creates for food and to grow. Nearly all plants require some amount of nitrogen, potassium and phosphorus to live, although each specific plant may require different levels of each. They also need magnesium to form chlorophyll, calcium to transport nutrients and sulfur to develop a strong root system. Plants also generally require some amount of iron, chloride, boron, copper and zinc, as well as molybdenum and manganese, both of which help to metabolize nitrogen.