Humic Acid vs Fulvic Acid: What's The Difference?

If you’ve dove into the world of plant nutrition, you’ve likely stumbled across the comparison of humic acid vs fulvic acid.

These are two vague elements that some growers swear by, while others are unaware of their existence and importance.

Whether they’re growing indoors or outdoors, it’s no secret that plants need an extra boost of nutrients here and there. But, you also need to feed your soil.

Finding the right compounds to keep your soil healthy and fertile can be tricky, especially if you’re working with a neutral growing medium that doesn’t have a lot of fertility to begin with, such as coco

Let’s explore the benefits of humic acid vs. fulvic acid for growing plants. 

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Humic Acid vs Fulvic Acid: What's The Difference?


If you’ve dove into the world of plant nutrition, you’ve likely stumbled across the comparison of humic acid vs fulvic acid.

These are two vague elements that some growers swear by, while others are unaware of their existence and importance.

Whether they’re growing indoors or outdoors, it’s no secret that plants need an extra boost of nutrients here and there. But, you also need to feed your soil.

Finding the right compounds to keep your soil healthy and fertile can be tricky, especially if you’re working with a neutral growing medium that doesn’t have a lot of fertility to begin with, such as coco

Let’s explore the benefits of humic acid vs. fulvic acid for growing plants. 

What’s the difference between humic acid and fulvic acid?

There tends to be some confusion when it comes to the categorization of humic acid vs. fulvic acid.

The reason for this is that both humic and fulvic acids - along with humates - fall into the general and broad category of humic substances. 

Humic substances are simply naturally-occurring organic compounds, typically resulting from plant, animal, and other matter as it decomposes. 

The difference between humic and fulvic acid really lies in how they break down. Both are essential for healthy soil.

the difference between humic and fulvic acid

What is humic acid?

Humic acid, often referred to loosely as a “humic substance,” is an organic compound. It is a vital part of humus (the organic part of soil along with coal and peat). 

In order to have healthy organic matter, you need humates, or humic acid. Humic acids are generally extracted from soil and can be coagulated to form solid pieces when an extract is acidified. 

Although they are often synthetically produced from mined minerals, humic acids are considered to be beneficial for plant growth. 

The molecules of humic acid attach to mineral ions like claws, helping prevent the minerals from being locked up in the soil. 

Although humic acid won’t necessarily fertilize your plants directly, it can make nutrients better available for your plants to absorb. This results in greater plant efficiency and better plant health. All this adds up to a plant better suited to meet its full potential.

Uses for humic acid

Humic acid presents several benefits to both indoor and outdoor growers.

It's biggest benefit is preventing mineral lockout in the soil, which helps prevent nutrient deficiencies in your plant.

It can also anchor nitrogen and make it more difficult for this nutrient - along with others - to be leached from the soil. 

Nitrogen is one of the most common nutrients in which a plant can be deficient, so adding a humic acid supplement to your feeding regimen can definitely help reduce your fertilizer needs. 

Humic acid also prevents the oxidation of iron, which is essential for plants to produce chlorophyll. When iron is oxidized, it is no longer available for plants to use in energy production. 

Humic acid is also known for being an excellent soil conditioner. It has a fantastic chelating ability that allows it to attach and bond to micronutrients so that your plants can absorb them. 

Other nutrients that humic acid can help increase the absorption rate of include:

  • Magnesium
  • Calcium
  • Zinc
  • Manganese 

Humic acid can be used during all stages of plant growth - from seed to harvest - and for any type of plant. 

It can be used powder that’s meant to be diluted with water, or as a liquid. This will allow you to make a foliar spray that can be applied to your plant’s leaves. Now, let’s compare it to Fulvic acid.

What is fulvic acid?

While humic acids are those that form small solid pieces when a strong base extract is acidified, fulvic acids are those that stay dissolved under the same conditions.

It is light yellow or brown but is soluble at all pH levels (both acidic and alkaline). It has a lower molecular weight, too, since it has more oxygen. 

Some growers simply look at this acid as a more “sophisticated” version of humic acid, as they are so closely related.

Fulvic acid has small particles that are better able to penetrate through the tough cell wall and mitochondria. As these small particles penetrate the mitochondria, they bring along with them vital nutrients and trace minerals. 

Uses for fulvic acid

Fulvic acid can help stimulate root development since it does a better job at getting through the rigid cell wall. It can also help the plant absorb water more efficiently. 

Due to its lower molecular weight, it is much better at crossing plant cell membranes and getting into leaves. 

It’s best used as a foliar spray for this very reason, but it can also be applied by mixing it into your regular irrigation system with other nutrients. 

When used in conjunction with certain fertilizers like seaweed extract and kelp meal, it can be even more effective. 

Both of these fertilizers contain hormones that stimulate plant growth, including cytokinins and auxin. They assist with cell division and enlargement, helping increase the speed at which your plants grow. 

It’s important to note that humic acid can do this, too. So do you really need to use both types of acid? 

Humic acid vs fulvic acid: do you need both?

Both fulvic and humic acids are necessary when growing in a hydroponic system, in particular. Most hydro setups use insert media like coco or hydroton, which do not contain any kind of humic or fulvic acid. 

Unfortunately, the same is also true of many soil grown plants, too. Due to mainstream gardening practices, soil is often depleted of these acids or contain only trace amounts. But do you really need both?

These acids work together synergistically

Humic and fulvic acid can work in harmony to boost your plant growth. While humic acid naturally improves soil health and growth, fulvic acid will help your plants take up nutrients more effectively. 

This can help save you money and time because you can reduce the amount of nutrients that you supply to your plants. Because they uptake more effectively, the concentration can be lowered. 

You’ll be able to grow healthy plants at a fraction of the cost. Plus, humic and fulvic acid can improve the drainage and water retention of the soil, if you are growing in this fashion. 

They support healthy microbial activity and lower the uptake of toxins - crucial if you are using synthetic fertilizers. 

Humic and fulvic acid can also improve photosynthesis and plant metabolism for improved growth.

What are the best humic and fulvic acid supplements for plants?

The best humic and fulvic acid supplements come down to how you want to grow.

If you are a home or hobby grower, just about any supplement you find on Hydrobuilder.com will work. Here are some of the highest quality products from our most reputable brands:

If you are a commercial grower cultivating consumable product, you should stick with OMRI listed supplements. These are tested to the strictest standards in terms of organic inputs.

Some of the best OMRI listed humic and fulvic acid supplements are:

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