16 Elements Necessary for Plants

The performance of your plants is directly related to the degree of the fertility of your soil. Like humans, plants require certain elements to grow well and to remain healthy.

Below is a list of elements essential for plant growth.  On the right are some sources from which plants may receive these elements.

Plants also contain Cobalt (Co), Iodine (I), Selenium (Se) and Sodium (Na), which are necessary to humans and animals which consume the plants, but which do not seem to be necessary for the survival of plants.  Aluminum (Al) and Silicon (Si) are also present in plants, but are not deemed necessary for humans nor animals for their survival.

Elements Required by Plants and Obtained From Soil and Fertilizers

Major Nutrients:  Nitrogen (N), Phosphorus (P), and Potassium (K)

Secondary Nutrients:  Calcium (Ca), Magnesium (Mg), and Sulfur (S)

Micronutrients or Trace Elements:  Boron (B), Chlorine (CI), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), and Zinc (Zn)

What These Elements Do for Plants

Major Nutrients

Nitrogen (N) is the main nutrient for strong, vigorous growth, good leaf color, and photosynthesis.  Plants that are almost all leaf (such as lawn grasses) need plenty of nitrogen, so the first number in fertilizers for lawns is especially high because grass must continuously renew itself after mowing.  The higher the number, the more nitrogen the fertilizer provides.

Phosphorous (P) promotes root development which helps strengthen plants.  It also increases blooms on flowers and the ripening of seeds and fruit.  Lots of phosphorous is great for bulbs, perennials, and newly planted trees and shrubs. They depend on strong roots, so fertilizers meant for these plants often have high middle numbers.

Potassium (K) improves the overall health of plants. It helps them withstand very hot or cold weather, defend against diseases, helps fruit formation, photosynthesis, and the uptake of other nutrients.  Potassium works along with Nitrogen so if you add nitrogen to the soil, it is important to add potassium at the same time.  Most soils already have some potassium, so the third number in the fertilizer analysis is usually smaller than the other two. Fertilizers for some tropical plants, especially palms, contain extra potassium because these plants have a special need for it.

Secondary Nutrients

Calcium (Ca) is important for general plant vigor and promotes good growth of young roots and shoots.  Calcium also helps to build cell walls.

Magnesium (Mg) helps regulate uptake of other plant foods and aids in seed formation. As it is contained in Chlorophyll, it is also important in the dark green color of plants and for the ability of a plant to manufacture food from sunlight.

Sulfur (S) helps maintain a dark green color while encouraging more vigorous plant growth.  Sulfur is needed to manufacture Chlorophyll.

Trace Elements

Boron (B) helps in cell development and helps to regulate plant metabolism.

Chlorine (CI) is involved in photosynthesis.

Copper (Cu) helps plants to metabolize nitrogen.

Iron (Fe) assists in the manufacture of chlorophyll and other biochemical processes.

Manganese (Mn) is needed for chlorophyll production.

Molybdenum (Mo) helps plants to use nitrogen.

Zinc (Zn) is used in development of enzymes and hormones.  It is used by the leaves and needed by legumes to form seeds.

Sources:  Gardener's Desk Reference, Anne Halpin, 1996 ISBN 0-02-860397-4;  Complete Guide to Florida Gardening