The essential elements (also called essential plant nutrients) are those that your plants require in order to grow. The three primary macronutrients are nitrogen, phosphorus and potassium. The three secondary macronutrients are calcium, sulfur and magnesium. Your plants need larger amounts of these nutrients than they need of micronutrients.
Chemical symbol: N Nitrogen is one of the three primary macronutrients. In gardening, nitrogen is the element that is most often credited for strong vegetative growth. It helps plants grow vigorously and produce a heavy yield. Among other things, nitrogen is essential for the synthesis of amino acids, which are the building blocks of proteins.
Chemical symbol: P One of the three primary macronutrients, phosphorus is essential for healthy plant growth. It contributes to developing long roots for better access to other nutrients. Phosphorus also helps plants use energy for fruiting and flowering. Symptoms of phosphorus deficiency include slow or stunted growth and bluish leaves.
Chemical symbol: K One of the three primary macronutrients, potassium helps plants grow strong cell walls, which in turn allows them to produce heavier yields. It also aids in efficient water use. Symptoms of potassium deficiency include weak growth and limp stems.