Plants (and animals) need 16 nutrients to survive.

Plants are made up of four main elements: hydrogen, oxygen, carbon, and nitrogen. Carbon, hydrogen and oxygen are widely available as water and carbon dioxide. Although nitrogen makes up most of the air in our atmosphere, it is in a form that is unavailable to plants. To be nutritious to plants, nitrogen must be made available in a "fixed" form. Only some bacteria and their host plants (notably legumes) can fix atmospheric nitrogen (N2) by converting it to ammonia.

6 of the 16 essential nutrients are called macronutrients as they are needed in great quantities, of which the first three are the main macronutrients: 

  • Nitrogen (N)
  • Phosphorus (P)
  • Potassium (K)
  • Calcium (Ca)
  • Sulphur (S)
  • Magnesium (Mg)

Micronutrients are needed in smaller quantities, but are also essential:

  • Boron (B)
  • Chlorine (CI)
  • Copper (Cu)
  • Iron (Fe)
  • Manganese (Mn)
  • Molybdenum (Mo)

Main Macro Nutrient Functions

Nitrogen (N) is the main nutrient for strong, vigorous growth, good leaf color, and photosynthesis. It is present in proteins, DNA and other components (e.g., chlorophyll).

Phosphorous (P) promotes root development which helps strengthen plants.  It also increases blooms on flowers and the ripening of seeds and fruit. 

Potassium (K) improves the overall health of plants. It helps them withstand very hot or cold weather, defend against diseases, helps fruit formation, photosynthesis, and the uptake of other nutrients.

Secondary Nutrients Functions

Calcium (Ca) is important for general plant vigor and promotes good growth of young roots and shoots.  Calcium also helps to build cell walls.

Magnesium (Mg) helps regulate uptake of other plant foods and aids in seed formation. As it is contained in Chlorophyll, it is also important in the dark green color of plants and for the ability of a plant to manufacture food from sunlight.

Sulfur (S) helps maintain a dark green color while encouraging more vigorous plant growth.  Sulfur is needed to manufacture Chlorophyll.