What are Plant Nutrients

Plant nutrients are the compounds that these living organisms need to survive and thrive. In nature, plants grow where the necessary nutrients are most plentiful. When you’re caring for your own garden, you’re responsible for making sure that each plant has access to the nutrients it requires for its growth. Providing the proper nutrients can make the difference between a sickly plant and one that thrives and produces an impressive crop.

There are three primary types of plant nutrients:

Macronutrients

If you’ve ever looked over the fertilizer selection at your gardening store, you’ve likely become familiar with the big three macronutrients that plants need to survive. Also known as primary nutrients, these are:

• Nitrogen (N): Promotes a dark green color, effective photosynthesis, and strong growth. You should give nitrogen more often to leafy plants like oats, grasses, wheat, and grain crops.
• Phosphorous (P): Promotes root development and growth. Flower bulbs, perennials, and young trees and shrubs need phosphorous more often.
• Potassium (K): Strengthens the plant and helps it withstand stress and disease. Give more of this nutrient to bushes and trees that flower or fruit.

Secondary Nutrients

Secondary nutrients are still essential for healthy plant growth, but they’re needed in smaller quantities than primary nutrients. The three secondary nutrients are:

• Calcium (Ca): Supports root health and leaf growth. Calcium is needed more often in sandy soil.
• Magnesium (Mg): Essential for efficient photosynthesis. Apply magnesium more often if you have a lot of rainfall, sandy soil, or high potassium levels.
• Sulfur (S): Supports the production of enzymes, vitamins, amino acids, and proteins. Apply this nutrient more in fall, so it’s ready for use in the spring.

Micronutrients

Micronutrients, also known as trace elements, are only needed in tiny amounts. However, you shouldn’t neglect these nutrients entirely, as a severe deficiency can cause trouble for your plants. Micronutrients include:

• Iron (Fe): Regulates and promotes growth.
• Boron (B): Helps support the formation of cell walls in growing tissues.
• Chlorine (Cl): Supports firm leaves and efficient photosynthesis.
• Manganese (Mn): Assists with photosynthesis.
• Zinc (Zn): Supports leaf expansion and stem growth.
• Copper (Cu): Aids plant respiration and metabolism of proteins and carbohydrates.
• Molybdenum (Mo): Assists in the nitrogen, oxygen, and sulfur cycles.

How Often Should I Give My Plants Nutrients?

How often to feed plants nutrients depends on many factors. There is no simple answer to this question. Rather, you must carefully assess the following factors:

Growing Method

The method that you use to grow your plants plays a major role in how and where they get their nutrients. Consider your chosen method carefully:

• Soil: If you grow your plants in soil, they may have ready access to many nutrients. Regularly fertilizing the plants will ensure that the essentials are taken care of.
• Soilless growing media: If you use a soilless growing media, you are responsible for feeding your plants all essential nutrients. These are provided through the water.
• Hydroponics: As with soilless growing mediums, hydroponics rely on nutrient absorption through the water. If you don’t supply the required nutrients, your plants have no other way to get them.
• Coco coir: Coco coir helps store and release nutrients, but it doesn’t provide them itself. This media does have trouble releasing calcium, iron, and magnesium, so you’ll need to apply these in especially high quantities along with other nutrients.

Nutrients Available

If your plants are in soil or a blend of growing mediums that contains soil, many nutrients will naturally be available. You can test the nutrients that are present in the soil with a DIY test kit or by sending a sample off to a lab. If the soil is deficient in certain nutrients, you will need to apply those more frequently.

Type of Plant

Each plant species has its own response to different nutrients. Some plants, like roses, need nutrients more often. Annuals tend to use more nutrients than perennials. Get to know the species in your garden so you can provide them with the nutrients they need most on a regular basis.

Plant Growth Stage

Plants require a different balance of nutrients at each stage in their life cycle. Get to know your plants so you can follow their growth cycles with proper nutrients. As you’ll see, different plants treat nutrients very differently.

In the early leaf stage of grains, the plants need some potassium and a small amount of nitrogen but virtually no phosphorus. The need for all three macronutrients increases through the tillering and stem elongation phases. The need for potassium spikes in the heading stage but tapers off as grains ripen. Phosphorus and nitrogen needs continue to increase throughout these stages. 

For fruit trees, boron is especially important in the pollination stage as bud development in the current season sets the stage for fruit in the following season. During the early development of fruit, nitrogen and phosphorus are critical. Calcium and potassium needs increase mid to late season. A late-season nitrogen application is often used to promote vigor the next spring.

Signs of Nutrient Deficiency in Plants