What Is Biochar & How To Use It In The Cannabis Garden?

What Is Biochar & How To Use It In The Cannabis Garden
December 12, 2019

Using biochar is perhaps one of the most revolutionary and sustainable agricultural practice that cannabis cultivators can adapt. Aside from increasing soil fertility and agricultural productivity, it also shows potential in mitigating climate change through carbon sequestration. This approach is nothing short of spectacular in terms of benefits for both the environment and the cannabis plants. Hence, knowing and understanding how to properly integrate its use is the garden is a must.

What Is Biochar?

The term biochar originates from two words: biomass and charcoal. It is a fine-grained, immensely porous charcoal with a massive surface area. In terms of physical attributes, it could be in powder or chunk form, but both are guaranteed to be entirely black. Thus, earning the moniker Terra Preta de Indio which means “Indian black earth.” Approximately 70% of its composition is carbon. The remaining proportion consists of nitrogen, hydrogen, and oxygen among other elements.

This charcoal-like substance is made by subjecting organic materials such as agricultural wastes to pyrolysis – a procedure which involves thermal decay of biomass in an oxygen-limited environment. The results are renewable, clean energy along with charred products sequestered with a stable form of carbon.

Biochar for Cannabis

The quality of materials used in producing biomass has a direct impact on the quality of the resulting product. Clean feedstocks with 10% to 20% moisture and high lignin content such as field residues and woody biomass are ideal for this process. After all, using contaminated biomass such as those from railway embankments or polluted land can introduce toxins into the biochar. Consequently, heavy metal pollutants such as copper, lead, zinc, mercury, nickel, and arsenic could contaminate the product and drastically increase the soil’s pH level upon application. This would ultimately have adverse effects on the plants as it would be hindered from absorbing minerals in the soil.

Biochar Vs. Charcoal

Biochar shares comparable properties with charcoal. However, its distinct characteristics are better harnessed when used as a soil modification agent. Hence, it is produced specifically for that purpose. On the other hand, charcoal distinguishes itself from biochar for it is produced to be used as a fuel, filter, coloring agent in arts, as well as a reductant in iron making.

Since the two are relatively similar in composition, both activated carbon and biochar have extensive surface area. However, biochar does not share the same bulk density or hardness of the latter. Moreover, the two also differ in terms of procurement methods. Biochar is subjected to heat of approximately 500°C with minimum oxygen, whereas charcoal is pyrolyzed at roughly 1000°C.


Biochar holds tremendous benefits when used in cultivating crops. In fact, it is one of the best-kept agricultural secrets to acquiring an exceptionally fertile soil. This is because it can refurbish even the most nutrient-depleted soil and bring it back to life. When further enriched with beneficial microbes, it can even boost plant growth and upsurge crop yields. The best part is that biochar does all these swiftly and economically. Furthermore, it also holds immense potential in remedying large-scale environmental problems such as global warming and climate change.

1. Boosts Soil Fertility

Biochar is typically used as a soil amendment because of its innate ability to enhance the quality of the growing medium where it is added. For instance, when pre-fertilized soil is incorporated with biochar, its efficiency doubles because biochar complements well with fertilizers and other growth boosters.

Apart from that, it also prevents nutrients from leaking out and locks in carbon which enhances the availability of soil minerals for plant absorption. Hence, reducing the need for fertilizers while promoting explosive cannabis growth. Furthermore, it can also reduce soil acidity and rebuild soil that has been deteriorated by improper cultivating practices or excessive use of pesticides or fertilizer.

2. Promotes The Proliferation Of Microorganism

Beneficial bacteria and fungi are essential in the development of healthy cannabis plants. Aside from making the nutrients more bioavailable for the plant roots to absorb, these microbes also ward off pathogens that may invade the crops.

Biochar helps foster microbial activity by serving as a habitat for countless beneficial microorganisms. The nooks and crannies in its vast surface area are hospitable breeding grounds for these bacteria and fungi which, in turn, play a pivotal role in plant flourishing.

3. Locks In Moisture And Minerals

Owing to its porous structure, biochar’s vast surface area enhances the soil’s water retention by ~200% as well as its Cation Exchange Capacity – a measure of the soil’s capacity to retain cations (positively charged ions). Since biochar has a predominantly negative net charge, it draws in polar substances like water and positively-charged minerals such as Calcium, Sodium, Magnesium, and Potassium which are all essential for proper cannabis plant development. Hence, increasing the amount of water and mineral concentration in the soil. Interestingly, when the biochar-enriched soil’s net charge leans more on the positive side (more cation), it starts capturing negatively charged ions such as Phosphorus, Nitrogen, and Carbon.

4. Lessens Pest Infestation

With its properties similar to activated charcoal, incorporating biochar in the cannabis garden makes it less appealing to insects and pests. Since the charred scent of the substance is too pungent, these harmful organisms might veer away from the garden. Hence, deterring pest infestation effectively.

5. Sequesters Carbon

Carbon sequestration is the process of capturing atmospheric carbon dioxide (CO2) and storing it in the soil to mitigate the rapid rise of temperature of the Earth’s atmosphere. This is precisely what biochar does which renders it an invaluable resource.

Since biochar production is a carbon-negative process, it minimizes the CO2 in the atmosphere by converting the unstable carbon found in biomass and agricultural products into a stable type of carbon that is not as reactive to oxygen. This stabilized carbon is then stored in the biochar. When incorporated into the soil, it creates a carbon sink which sequesters the element in the soil for hundreds and thousands of years.

Moreover, since the burning and natural decomposition of agricultural wastes and biomass emits large amounts of CO2 in the atmosphere, converting these substances into biochar essentially minimizes the emission of greenhouse gases and defers global warming.

6. Cleans Polluted Groundwater

Studies show that biochar is exceptionally effective in trapping water contaminants in its porous surface. Hence, opening up the possibility of using it in decontaminating groundwater and lowering the cost of water filtration.

7. Serves As Alternative Source Of Renewable Energy

Throughout the production of biochar, clean and renewable energy is produced as a byproduct. This can be utilized as an alternative to burning nonrenewable fuel sources which further exacerbates global warming.

8. Mitigates Climate Change

Biochar helps alleviate the effects of climate change by enhancing the soil and reducing the need for chemical fertilizers. This means that greenhouse gas emissions would be lessened. Furthermore, the enhanced soil fertility would promote the healthy development of plants which, in turn, takes in CO2 during photosynthesis.


Despite its long list of benefits, the use of biochar also entails several drawbacks especially when used or produced in excessive amounts. Needless to say, the key to preventing such problems from occurring is proper modulation of its use and production.

1. Possible Decline In Yields

Notwithstanding biochar’s soil boosting effects, it could decrease the crop yields and inhibit germination when used excessively. It could be noted that the porous nature of biochar adsorbs water and nutrients. When used disproportionately, it hoards all the water and nutrients and reduces its bioavailability for plant roots. Thus, negatively affecting the plant growth and ultimately, amount of yield.

2. Some Can Be Sources of Contaminants

The composition of biochar chiefly depends on the material it is made out of. When contaminated manure or biomass is converted to biochar, it would retain impurities such as heavy metals, volatile organic compounds, polycyclic aromatic hydrocarbons, and dissolved organic carbon which could have devastating effects when mixed with growing mediums.

3. Risk Of Respiratory Disease

The fine particles of ash associated with biochar could be a health concern especially when inhaled chronically. Besides, it could irritate the eyes and skin upon prolonged exposure.

The 5 Best Biochar Brands

Biochar production is a meticulous and stringent process that involves the use of sophisticated machinery such as a pyrolysis oven. Hence, buying biochar products from reputable manufacturing companies is more recommended than creating DIY versions at home. Not only will it be more convenient, but one could also be assured that the products are appropriately pyrolyzed according to standard procedures.

That being said, it is imperative to scrutinize the brands before buying the products to assure that the biochar would be of the highest quality. Reading product reviews from fellow cultivators could also serve as a basis for forming a judgment on whether to patronize a particular brand or not.

1. Green Texan Organic Farms Biochar Soil Amendment

Green Texan Biochar

Available in bulk form, fine powder, or chunks, this 100% turbo-charged biochar by Green Texan Organic Farms is specially procured to enhance the structure and drainage of the soil. Moreover, it is inoculated with a mix of the world-renowned EM-1® (Effective Microorganisms®) microbial inoculant developed in Okinawa, Japan. The EM-1® mix boasts its ability to enhance the soil health with the microbial activity of naturally occurring beneficial microorganisms namely lactic acid bacteria, yeast, and photosynthetic bacteria. As a bonus, this granular biochar is certified low-dust so it would not likely induce respiratory problems upon application. A 2.5-gallon pack of this soil amendment is priced at $17.99.

2. Wakefield Premium Biochar Soil Conditioner

Wakefield Premium Biochar

With the Think globally, act locally movement in mind, Wakefield manufactured one of the highest quality biochar in the market. This Premium Biochar Soil Conditioner is made from 100% soft pine wood biomass, so it is guaranteed to be free from contaminants. Every batch of the product also underwent strict procedures of fast pyrolysis. The resulting biochar is that of a fine granule with a consistent particle size of 1mm to 2mm. The merit of this product is reflected in its large number of satisfied customers who swear by Wakefield biochar’s effectivity in boosting yields and even eliminating unwanted odors in the grow room. A 7.5-gallon box of this premium soil conditioner could be bought for $41.99.

3. California’s Greenest Low-Dust Biochar Box

California’s Greenest Low-Dust Biochar

With the commitment to pioneer the way to producing organic, top-quality products with the use of sustainable technologies, California’s Greenest offers premium low-dust biochar products made from recycled wood and tree trimmings. Hence, it is guaranteed to be 100% OMRI organic. The company also certifies that the materials used in producing the biomass are naturally and sustainably grown so it is free from pollutants and no biological activity has been disrupted in the process making of this product. As such, plants grown with the aid of this biochar are said to be healthier, more flavorful, more vibrant, and more resistant to pests and diseases. This low-dust biochar is sold in 7.5-gallon boxes for the price of $38.99.

4. Organic Mechanics Garden Center Biochar Blend

Organic Mechanics Garden Center Biochar

Organic Mechanics’ Biochar Blend boasts its all-natural biochar made from the natural mix of compost, worm castings, Alfalfa meal, kelp, and bone char. Together, these materials create top-quality biochar rich in valuable nutrients such as phosphorus, calcium, zeolite, and azomite which ensures delicate nourishment of microbes and plant roots. The result is vibrant, disease-resistant, and fast-growing plants with a healthy network of well-developed roots. This biochar blend is sold at $44.95 per 20 gallons.

5. Soil Reef Gardeners Blend

Soil Reef Gardeners Blend Bioachar

Soil Reef’s Gardeners Blend is a premium biochar mix made with the combination of 50% biochar, top-grade organic compost, worm castings, and kelp meal. It is sustainably produced from wood waste and forest residue. Thus, the product boasts its all-natural composition that mimics the Earth’s natural makeup. With its use, there is less need to feed the plants with fertilizers as the biochar-compost-worm casting blend can adequately provide the crops with the essential nutrients for growth and survival. 7.5 gallons of this blend is sold at $47.95.

How To Use It

The rate and manner of application of the biochar will mostly depend on specific soil conditions in the garden. Moreover, since different manufacturers make use of varying biomass products in making the biochar, the procedures and recommended amount per cubic feet varies. Hence, it is advised to refer to the specific product instructions included in the purchased biochar. In the absence of a specific instruction though, the general advice is to use 5% to 10% of biochar in the top 6 inches of the soil.

Word "How To"

1. Charge Up The Biochar

Charging the biochar or simply put, mixing it with compost before incorporating it into the growing medium is an essential step because of its tendency to soak up nutrients and microbes. If it is directly applied to the soil without charging it first, it will soak up the existing nutrients and microbiology from the ground which can reduce the fertility of the soil instead of increasing it.

The most common method of charging biochar is by mixing it with compost in equal parts (50/50). After which, let it sit for at least ten days so that the biochar will have ample time to soak up the microbes and nutrients.

2. Incorporate It In The Soil

The suggested approach for using biochar will differ depending on how healthy or nutrient-depleted the soil is. Before using biochar in the garden, determine the state of the land first. For soil improvement, lesser amounts may be used, but if the goal is for structural improvement in a parched land, this would definitely require using more significant amounts of biochar.

It is also recommended to apply the biochar on days when environmental factors will not be a hindrance. This is because exposure to UV light, wind, and water erosion could cause significant losses in its effectivity. This, of course, will not be a problem in indoor setups.

There are three ways of integrating biochar in the soil namely top-dressing, tilling or hand mixing.

Top Dressing

For cultivators who practice no-till gardening, the topsoil dressing method works best. It is also the most straightforward method out of the three.


  1. Scatter the charged biochar on top of the soil then add water until it appears wet.
  2. Let it rest for an hour or two then add a thin layer of compost. This would help boost soil fertility.
  3. Build up the soil fertility over time by adding 80% compost and 20% biochar mix to the topsoil as soon as the compost starts to decompose or as often as deemed necessary.


The biochar needs to be as close as possible to the root zone for it to work its wonders properly. For this reason, the tilling method is more effective than topsoil dressing.


  1. Spread the recommended amount of charged biochar on the topsoil.
  2. Using a hoe or tiller, agitate the soil to mix biochar and the growing medium. Ensure that the soil amendment is thoroughly incorporated. However, be careful not to overdo the tilling as it could have adverse effects on the soil and the microbes in the biochar.

Hand Mixing

This method is ideal to use when the plants are already in the growing medium or when it is potted. It is not as efficient as tilling the soil with hacking tools, but it is better than topsoil dressing as it allows for the thorough incorporation of the biochar without aggressively agitating the soil.


  1. Sprinkle adequate amounts of the charged biochar around the plant.
  2. Gently agitate the soil and incorporate the amendment to the soil using a gloved hand or small rake. However, take extra caution not to damage the plant roots in the process. Otherwise, this could negatively impact crop growth.

Biochar For Explosive Plant Growth

Biochar’s many advantages for both the environment and agricultural systems make it a truly invaluable tool for regenerative cultivation. Not only does it boost soil fertility and make it more optimal for cannabis growth, but it also holds immense potential in remedying the long-standing problem of global warming.

Cannabis Cultivation

This all-natural product also proves that organic solutions are best suited for improving the soil condition and ultimately, plant health. Thus, incorporating biochar in the cannabis garden is a smart choice that – ideally – every cultivator must adapt. Not only does biochar help induce explosive plant growth, but it also helps heal the environment that humans eroded.