Nitrogen (N), Phosphorus (P), and Potassium (K) are the three primary nutrients required for plant growth.
Nitrogen is required in high amounts during vegetative growth and in lower levels later in life cycle. Plants that do not the required amount of nitrogen during their growth cycles will get nitrogen-deficiency which causes yellowing between leaf veins and then full yellowing. Further nitrogen deprivation will result in plant death.
Phosphorus is most required during the germination, seedling, cloning, and flowering stages. A lack of phosphorus will stunt plant growth and will have dead blue/black botches. Severe deprivation will cause plant leaves to shrivel, die and fall off.
Potassium is most important in plant water usage, the movement of sugars, and cell division (which is required for plant growth). Potassium also encourages strong root growth. Lack of potassium will cause yellowing in leaves, brittle stems, and plant death.
We designed our nutrient solutions to reflect the importance of proper NPK balance at each stage of growth.
Now these are the primary nutrients that are required for plant growth. Plants in addition need secondary nutrients.