Macro, meso, and micro: basic elements for plant nutrition

• Macro elements are nitrogen (N), phosphorus (P), and potassium (K). 
• Meso elements are magnesium (Mg), calcium (Ca), and sulfur (S). 
• Micro elements or trace elements are iron (Fe), manganese (Mn), zinc (Zn), boron (B), copper (Cu), molybdenum (Mo), and silicon (Si). 

For growth to occur there must be a proper balance between these categories. The table gives you an idea of the optimum nutrient element ratios in plant tissue.