Lesson 1.1 The Essential Elements
What are Essential Elements?
Plants are remarkable organisms that sustain life through their ability to absorb nutrients and water through their roots, while also taking in carbon dioxide from the air. When combined with sunlight, these inputs power the processes plants need to grow, reproduce, and thrive.
To do this effectively, plants rely on 17 essential elements, or nutrients, each playing a unique role in the plant’s health. These elements are vital for key functions such as photosynthesis, cell division, root growth, flowering, and fruit development.
Essential elements are classified based on the amount required by the plant. While all 17 are critical, plants need some in larger amounts than others; these are called macronutrients. Others are needed in much smaller doses and are called micronutrients.
Macronutrients
The macronutrients are the major building blocks. Nitrogen, for example, supports leafy green growth. Phosphorus promotes strong root systems and helps plants bloom and set fruit. Potassium improves stress tolerance and regulates water movement through the plant. Secondary macronutrients include calcium, magnesium, and sulfur, which contribute to functions ranging from cell wall strength to chlorophyll production.
Micronutrients
Micronutrients may be required only in trace amounts, but they are equally important. Iron supports chlorophyll formation, zinc and copper are involved in enzymes and growth hormones, and boron is essential for cell wall development and new tissue growth. Even in tiny amounts, these nutrients are critical for plant function.
Carbon, Hydrogen, and Oxygen (non-mineral)
In addition to mineral nutrients, plants need three elements that do not come from the soil: carbon, hydrogen, and oxygen. These are obtained from air and water rather than minerals, but they are essential. Without them, photosynthesis would not occur, and plants could not survive.
Altogether, these essential elements make up the complex nutritional needs of plants. Knowing what they are—and how they function—can help you better support healthy growth in your garden or on your farm.
The table below shows the role each essential element plays in plant health and where the plant obtains that element.
Nutrient Solubility & Availability
When plants take up nutrients from the soil, they are not consuming solid particles. Instead, they rely on soil water—called the soil solution—to deliver nutrients in a form they can use. The soil solution is the thin film of water that fills the small spaces between soil particles. It acts as a nutrient-rich medium surrounding the roots, carrying dissolved minerals, salts, and gases.
Most nutrients are absorbed by plants as inorganic ions—tiny charged particles that are dissolved in water. Because these nutrients are in solution, plants can take them in directly through their roots.
The catch? Not all nutrients are equally available at all times. Their solubility—how easily they dissolve into the soil solution—can change depending on factors such as soil pH, moisture, temperature, and microbial activity. If a nutrient is not very soluble under certain conditions, it may be present in the soil but unavailable for uptake.
So, when we talk about plant nutrition, it is not just about how much of a nutrient is in the soil—it is about how available it is in the soil water, ready for uptake. That is why managing factors such as irrigation, soil pH, and organic matter is critical for maintaining healthy, productive plants.
"Soil solution" refers to the liquid phase of soil, essentially the water that fills the spaces between soil particles and air. It contains dissolved minerals, salts, gases, and other soluble compounds.
