Key Plant Macro and Micronutrients

Macronutrients vs Micronutrients

All plants need specific sets of nutrients to grow and thrive. These include both macronutrients, which plants need in large quantities, and trace amounts of micronutrients. Read on to find out about what nutrients plants require to complete their life cycles, from germination to seed production.

Macronutrients vs. Micronutrients

Also known as primary nutrients, macronutrients are those required in large amounts. Most gardeners and growers are familiar with the NPK ratios on conventional fertilizers, but nitrogen, phosphorous, and potassium are not the only macronutrients. Carbon, hydrogen, and oxygen are also included in this category, but plants typically derive these life necessities from their environments.

In some cases, secondary nutrients also fall under the umbrella term of macronutrients. These include calcium, sulfur, and magnesium. Plants need these in moderate amounts, not in large quantities, but theyíre still essential to support healthy growth.

Micronutrients, also referred to as trace nutrients, are only required in very small amounts. They include substances like boron, chlorine, copper, iron, manganese, molybdenum, and zinc. Some plants also need silicon, sodium, cobalt, nickel, and vanadium to perform key functions. Growers can get the macro- and micronutrients they need to help their plants thrive from Agron.

Functions of Macronutrients

Macronutrients derived from air, water, and soil provide the backbone of healthy growth. Plants use each of them to accomplish different goals. Hereís what growers need to know about each of these primary nutrients.


Carbon is essential for forming proteins, starches, and cellulose. Plants fix this nutrient through photosynthesis by dividing carbon dioxide from the air into carbohydrates. These carbohydrates can then be stored and transported throughout the plant.


Hydrogen helps plants build sugars. These are required to facilitate healthy growth and drive electron transport chains required for both photosynthesis and respiration. Plants obtain all the hydrogen ions they need from water.


Plants produce oxygen as a byproduct of photosynthesis, but they also need it to undergo cellular respiration and break down glucose to generate ATP. Terrestrial plants acquire oxygen from a variety of molecules from the air via their leaves and from the soil water via their roots.


Nitrogen is an essential component of amino acids, which plants use to build proteins. Theyíre also an important constituent of chlorophyll, so without sufficient nitrogen, plants will experience stunted growth and chlorosis. Growers need to provide nitrogen to their plants through the soil or, in hydroponic systems, in the nutrient solutions themselves. Either way, the plants uptake it through their roots.


Phosphorous is a main structural component of the nucleic acids and a constituent of fatty phospholipids, which are essential for membrane development. Growers need to add phosphorous to their soil using fertilizer, bone meal, or liquid plant food to avoid phosphorous deficiencies.


While nitrogen and phosphorous form the building blocks of plant metabolism, potassium is more essential for maintaining healthy leaves and growing points. It helps to regulate internal moisture and acts as a catalyst and condensing agent of more complex substances. It also contributes to photosynthesis under low-light conditions.

Key Micronutrients

Plants donít use secondary and trace nutrients in the same quantities, but they are still essential to support healthy growth. Hereís what growers need to know about each of these key components:


Sulfur is essential for chloroplast growth and function. Legumes also use it to fix nitrogen and convert nitrate into amino acids and proteins. Sulphur cannot be mobilized from older leaves for new growth, so plants need access to the substance throughout their life cycles.


Calcium aids with the transport of other key nutrients and helps to activate plant enzymes. Itís also involved in photosynthesis and plant structure. Calcium deficiency can lead to stunting during the plantsí vegetative stages and blossom end rot during the flowering stage.


Magnesium is a constituent of chlorophyll. It also acts as a carrier in enzyme reactions. Itís extremely mobile, which means older tissues can transport magnesium to younger ones. Deficiencies tend to appear in older plant tissues first.


Iron presents as an enzyme cofactor. It is also necessary for photosynthesis, although it is not a structural part of chlorophyll. Plants also require copper to transport iron.


Molybdenum assists in building amino acids and metabolizing nitrogen. Plants use it to reduce nitrate into usable enzymes, so deficiencies can lead to reduced productivity.


Boron supports many vital plant functions, from cell division and salt absorption to flowering and fruiting. It helps to metabolize amino acids, carbohydrates, calcium, proteins, and water. A lack of boron can lead to stunted fruiting bodies and roots.


Plants use copper for photosynthesis and to move iron throughout the plant. Itís involved in manufacturing lignin and grain production. Copper isnít readily available in most soils, so growers will need to add supplements.


Manganese is critical for building chloroplasts. Deficiencies lead to discoloration of the foliage and prohibit optimal photosynthesis, stunting the plantsí growth.


Sodium helps to regenerate phosphoenolypyruvate. It can also assist in the regulation of stomata.


Zinc plays an important role in DNA transcription. Deficiencies can lead to stunted leaf growth.


Silicon strengthens cell walls to increase plant strength, health, and productivity. It can also improve drought, frost, pest, and disease resistance, improve yields, and increase root mass and density.


Nickel activates an enzyme called urease that is involved in metabolizing nitrogen. Without it, plants can accumulate toxic levels of urea, leading to necrotic lesions.


Cobalt isnít essential for all plant species. It is, however, very important for nitrogen-fixing species like legumes since it keeps the bacteria associated with these plants healthy.


Most plants donít need vanadium, although some require it in very low concentrations. Most plants can use vanadium as a substitute for molybdenum in depleted soils.

The Bottom Line

Like all living things, plants require certain nutrients to grow and thrive. Most of them are found in healthy soils, but growers who plan to reuse soil instead of buying it new every year and those who use hydroponic systems to grow indoors need to supplement macro and micronutrients. The easiest way to do this is to buy plant foods and supplements tailored to supporting specific types of growth.