The concepts of nutrition and nutrients are often overlooked, merely blended together, or considered as the same or interchangeable idea. Mengel and Kirkby (1982) best described the difference between nutrition and nutrients as nutrition being the "supply and absorption of chemical compounds needed for growth and metabolism" and nutrients as simply being "chemical compounds required by an organism" for whatever undefined reason.

The classification of nutrient elements into the macro- or micronutrient category is purely arbitrary at best if based solely on the physiological requirements of the plant. For example, often the leaf tissue content of Mn is far in excess of the plant's physiological requirements for Mn . The classification of elements into macro- and micronutrients, based on biochemical concerns, is probably more sensible and appropriate.

Living plants consist of 27% organic matter (stems, roots, leaves, flowers and fruit), 70% water and 3% minerals (inorganic ions) (Mengel and Kirkby, 1982). 

Successful cultivation of greenhouse vegetable crops on Grodan® growing media  requires an understanding of plant nutrition. It is beneficial to understand the role(s) of each essential mineral within the plant in order to detect early symptoms of nutrient deficiency. Nutrient deficiency depends on two key factors:

1. The role of a particular nutrient within a plant

2. Whether or not that element can be translocated from one area of the plant to another.