What Does Humic Acid Do for Plants and How to Use It?


Humic acid can help your plants grow stronger and faster. What is it and what does it do?
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If you’re trying to grow healthy plants, it’s essential to understand what humic acid is and how it impacts the plants in your landscape or garden.

Continue reading to learn more about humic acid.

What is Humic Acid?

In simplest terms, humic acids are groups of molecules that attach to plant roots that help them take in water and nutrients. The presence of high levels of humic acid can increase yields. It can be found in lignite, peat, and soil. It is a dark-brown humic water-soluble biostimulant that increases plant growth and vigor. It does not provide nutrients or kill pests.

How Does It Work?

Humic acids are essential as a medium for transporting nutrients from the soil to the plant because they can hold onto ionized nutrients, preventing them from leaching away. Humic acids are also attracted to the depletion zone of the plant root. When they arrive at the roots, they bring along water and nutrients the plant needs.

The depletion zone is the area close to the root of a plant from which the root draws (depletes) nutrients. This zone can lack water and nutrients if humic acid is not present. 

A plant’s root more easily absorbs positive ions because the root has a negative charge. In other words, the positive (cation) is attracted to the negative (the living root). Humic acids hold cations (positive ions), which can be more easily absorbed by a plant’s root, improving micronutrient transfer to the plant’s circulation system. 

sprouts growing in wet black soil

Why Is It Good For Plants?

Humic acid is a type of plant biostimulant. Biostimulants are also called plant conditioners or bio-enhancers.

Biostimulants do not provide nutrients. They also do not kill pests or pathogens but improve a plant’s stress tolerance to weather, pests, and diseases. They increase nutrient uptake and utilization in plants through various means and improve plant quality and yield. 

bunch growing green plants in farm

How to Use It

While it may sound like a complicated chemical, using it is very easy. Once you know how to use humic acid for plants, it’s a great addition to your amendment routine. Growers can apply humic substances in various ways. Two means of applying are as a foliar application or as a seed coat. These products are available in liquid and powder forms, as well.

Because plants do not take up humic acids, nor do they leach out of the soil, once applied, they will remain in your growing media for a long time. The benefits, such as improved soil structure, will last through multiple growing seasons. Of course, further applications of humic substances will only help your plants. 

The best time to apply humic acid is during the reseeding season in the spring or fall. It should be applied after spreading fertilizer. Water-soluble humic acid should be applied at a time in the day when there is less chance for the liquid to evaporate. Pelleted forms will need to be watered to help them break down.

Carley Miller
Carley Miller is a horticultural expert at Bustling Nest. She previously owned a landscaping business for 25 years and worked at a local garden center for 10 years.
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