Plants need a balanced diet, too. Nitrogen, phosphorus, and potassium are the main nutrient ingredients in any fertilizer, but there are other important nutrients that are found in smaller amounts.
Calcium improves general plant vigour and promotes growth of young roots and shoots.
Magnesium is used by plants to make their food. It is important in development of chlorophyl and in the photosynthesis process.
Sulfur is a key ingredient in chlorophyl, the tool plants use to make their own food via photosynthesis.
Iron is found in very small concentrations in fertilizers, but it is important because most soils lack iron. Iron helps plants to keep their chlorophyl, the tool they use to make their own food via photosynthesis, healthy.