• Plants absorb nutrients dissolved in water through their roots.Zedcor Wholly Owned/PhotoObjects.net/Getty Images
  
  Plants form the basis of life on Earth by converting energy from sunlight into chemical energy usable by not only the plants themselves but organisms higher in the food chain. Although they manufacture their own energy, however, plants need more than just sugar to survive and absorb 13 different mineral nutrients from the soil with their roots. In order to grow a healthy and vibrant flower garden, your plants must receive the correct amounts of all of these nutrients.
  
  

Nitrogen

• Nitrogen is the building block of all life on Earth and is considered one of three primary macronutrients for plants: mineral nutrients required in relatively large quantities and essential for survival. Nitrogen occurs abundantly in every plant cell but, in particular, helps plants to use energy stores, form protein and develop a strong structure. If your garden lacks nitrogen, you may notice the leaves take on a yellowish tinge. When purchasing fertilizer, the first of three numbers indicates the percentage of nitrogen.
  
  

Phosphorus

• Phosphorus is the second primary macronutrient, and, among its many functions, it plays an important role in encouraging your flowers to bloom. In addition, it helps in energy production, encourages growth and helps plants to withstand stress. Phosphorus-deficient plants produce fewer blooms, have weakened structures and develop a purplish tint to their leaves. The second number on fertilizer packaging tells you what percentage of phosphorus it contains. Use care when fertilizing your flowers with phosphorus, as it can act as a highly destructive water pollutant.
  
  

Potassium

• The final primary macronutrient, potassium, helps plants to move water and other compounds in and out of their cells, as well as playing a role in photosynthesis and energy metabolism. Potassium-deficient plants cannot control the movement of water out of their cells, causing their leaves to dry out. They become more susceptible to pests and diseases. The third number on the fertilizer package shows the percentage of potassium it contains.
  
  

Sulfur

• Flowers serve a reproductive function for their plants and provide the site where sexual reproduction occurs. A fertilized flower produces seeds, an action which requires sulfur, one of three secondary macronutrients plants need. Sulfur also aids with photosynthesis, protein formation, growth and resistance to cold weather.
  
  

Copper

• Cooper is a micronutrient required by plants in only small quantities. Like sulfur, however, copper specifically helps flowers to carry out their reproductive function by aiding in the growth of reproductive structures. Copper also helps the flowering plant's root system use energy and aids in the breakdown of protein.