Humic and Fulvic Acids: What They Are, And How to Use Them
3 min

Humic and Fulvic Acids: What They Are, And How to Use Them

3 min

Humic and fulvic acids can greatly benefit your plant’s growth.They can help increase your yield, make your plants more resistant and aid their growth in many ways.

Humic and fulvic acids are essential for healthy plant growth. They help to increase the nutrient uptake of plants and can condition soil for a more efficient use of fertilizers. They help in establishing healthier roots, help increase yield and are beneficial for an overall better plant development. Organic soil grows and soil-less grows can take advantage of the benefits of humic and fulvic acids.

The issue marijuana growers face is that they are normally using unnatural systems that are low in humic and fulvic acids or that these can be entirely absent. Hydroponic systems in particular often use sterile mediums like Hydroton, rockwool or perlite that don’t contain any humic or fulvic acids at all. Even growers who grow in soil should know that soil is normally depleted of humic-fulvic acids or that it may contain less than optimal amounts.

A simple explanation of the both can be that humic acid helps soil health and general growth while fulvic acid (which is extracted from humic acid) acts as a fertilizer booster.


Humic acid is dark brown or black organic matter that is water-soluble at more alkaline levels. It derives from the organic components of soil such as humus or peat and is produced by microorganisms that break down dead organic matter.

Humic acid is an excellent soil conditioner due to its high molecular weight. It works well for soil and soil-less substrates where it supplements and rejuvenates the growing medium at the same time. Adding humic acid will improve the medium’s water retention and it will facilitate the movement and availability of nutrients.

Humic acid is a great chelating agent. It attaches itself to micronutrients where it forms a bond so that the mineral can be more easily absorbed by plants. It is also promoting a better ion-exchange and supports better buffering capabilities. When elements such as calcium, iron, magnesium, zinc and manganese can be absorbed more easily, it benefits both, the growth of plant matter and root mass. This beneficial effect of adding humic acid effect can be observed in soil grows and hydroponic grows.


Fulvic acid is humic material that is light yellow to yellow-brown in color but it is soluble at all pH levels. Science believes that Fulvic acid is made up of DNA from dead organic life forms which means that it is between the organic and mineral world. Due to the close relationship with humic acid, some see fulvic acid as being a “fancier” version of humic acid.

Fulvic acid has a lower molecular weight than humic acid. It has less carbon but a higher oxygen content. Because of its lower molecular weight, it can easier penetrate plant leaves and the plant’s cells. It can even enter the plants' mitochondria. Because of this characteristic of fulvic acid, it is very efficient when applied as root drench or foliar spray.


We can apply humic substances with many different growing techniques. We can take advantage of them whether we grow in soil or soil-less. They work with irrigation, when added to a watering regimen or if we supplement them to soil in dry form. Humic substances are also beneficial for seedlings, cuttings and clones

Humic acid and fulvic acid can chelate minerals into a form that makes them easier available and easier to absorb to our plants. One side-effect here is also that harmful toxic substances become less of a threat. Adding humic acid and fulvic acid increases water retention and filtration ability of the medium so that plants can tolerate water shortages and dry spells better. As a result, stress on the plants is reduced and the germination rate is increased. The same beneficial effect encourages root growth, plant metabolism and cell division.


When you grow in soil, you can add liquid or dry humic acid that is diluted with water. You can feed it directly to the soil. This is the recommended application method for clones or seedlings. It can also be beneficial if you supplement your seeds with humic acids prior to germination.

Some growers like to make compost tea where they add humic acid in powder or liquid form before they start brewing.

For foliar sprays, humic acid powder or liquid can be diluted with water. You spray the solution liberally on the plant leaves. Applying fulvic acid as a foliar spray has another, curious benefit that is still not entirely understood: It can substitute sunlight. When it is overcast for a longer time period, a foliar application with fulvic acid can make photosynthesis continue despite less than optimal weather conditions. Parks and golf courses are already taking advantage of this effect to rejuvenate and green-up areas that are shaded. Fulvic acid has big potential to provide its benefits for many different types of plants and crops.


When you shop around for humic substances, either online or in well-sorted garden stores, you can find various forms of them in different concentrations. It can be a good idea if you buy them in person from a reputable garden store where you can have staff advise you what type would be best. This can be helpful if you want to avoid overdosing. Otherwise, make sure to always read the instructions that come with the product. As a rule, applying humic substances frequently but in smaller doses is recommended over giving them less frequent but in larger doses.

Do you have experience supplementing your plants with humic and fulvic acids? How did it benefit your grow? You can share your experiences in the comments!

Steven Voser
Steven Voser
Steven Voser is an independent cannabis journalist with over 6 years of experience writing about all things weed; how to grow it, how best to enjoy it, and the booming industry and murky legal landscape surrounding it.
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