Growing Cannabis in Coco Coir: Why Coconuts Matter

There are many advantages to cannabis cultivators who grow in coco coir.

Coco coir offers cannabis growers an alternative or additive to the substrates they already use in their hydroponic and soilless growing situations, including greenhouse containers and field production. 

Coco coir is the number one alternative to peat-based, soil, or stonewool, which explains why demand increases every year, as stated in a recent article in Grower Talks magazine. 

“Coconut coir is the number one peat alternative on a global scale, and the global demand increases every year. In the past 20 years, the production and processing of coir pith have increased from 1 to almost 10 million m3 in 2019. Despite the success, the demand is high, and many suppliers already cannot supply enough product to meet the demand—and that was before COVID.” – Dr. Brian E. Jackson, growertalks.com

Peat Moss vs. Coco Coir

Peat moss-based grow mixes have been around for a long time and are capable of producing a good cannabis crop in addition to many other greenhouse crops. When mixed with vermiculite and perlite, it offers a growing media that retains moisture and drains well. 

Peat moss-based substrates contain plant nutrients and are reusable, but only up to a point. On the other hand, you can use coco coir repeatedly as long as the nutrients your plants need are maintained within the media. The slow degradation of coco coir is due to a high lignin and cellulose content. Peat moss-based media is acidic (between 3.3 to 4), while coco coir has a neutral pH.  

There are several advantages to growing cannabis in coco coir. Derived from what would be a waste product of coconut harvests in Sri Lanka and other tropical zones, it is a renewable resource, unlike peat-based media, which is mined from peat bogs in northern Canada and to a lesser extent in Europe. There are several other reasons to consider using coco coir to grow a superior crop of cannabis. 

• Coco coir is pH neutral, which makes managing nutrients in hydroponic systems a little easier. 
• It hydrates quicker than peat-based mediums, retains water well, and has an excellent cation exchange capacity.  
• Unlike peat-based growing mediums, which decompose in a matter of months, coco coir is a long hauler, taking decades to break down. This makes coco coir a good choice for closed-loop systems where it can be reused after sterilization.
• Adding coco coir to pots and containers can help water retention in otherwise fast-draining soils. 
• When used in hydroponic growing, fewer nutrients leach from the media into the water, throwing the nutrient solution out of balance.
• Coco coir is versatile; you can use it in seedling production, cuttings, and growing mature cannabis plants.
• A quality coco coir mix can save up to 90% of water usage in a greenhouse, improving your bottom line.

How to Grow Cannabis With Coco Coir

Like any growing media, there are a few things to learn about cultivating with coco coir before entrusting your cherished cannabis plants to this choice of growing media. While coco pith is excellent at retaining water, it doesn’t provide good aeration on its own. In hydroponic systems, this may mean adding perlite at the rate of about 30-50%. However, by using a coco coir product that only contains the pith you would be lucky to achieve 15% aeration in the mix by adding perlite. 

Growers can achieve excellent results by using coco coir alone, but only if the coir is produced in a way that mixes the pith and coco chips. Coco chips are evenly cut sections of the husk of the coconut. By mixing the pith and coco chips over 30% aeration can be achieved. Aeration in the mix is important because it allows the roots to “breath” and the media to dry back as the plant absorbs nutrients and the moisture held in the media.  

Coco coir is an inert substance, meaning it lacks nutrients for good plant growth. Coco coir enthusiasts, including those in the cannabis space, are well aware of the need to supplement feedings by adding calcium and magnesium, i.e., Cal-Mag, as necessary. Like any media, you should keep a sharp eye on nutrients, pH, and EC and adjust your feeding and irrigation programs accordingly. Maintain pH between 5.5 and 6.3 for growing cannabis. 

Cannabis growers also like to mix things up, creating their own “super substrate” by adding worm castings, mycorrhizae, and slow-release fertilizers to their coco coir growing medium. Some also choose to go with a 50/50 mix of coco coir and a peat moss-based growing medium.

Coco Coir and Hydroponics

Because coco coir is an inert growing medium, people think it’s advantageous for hydroponic growers who want precise plant nutrient delivery. In other words, the grower has more control over inputs. A suitable pH and EC tester help growers effectively monitor the mixing tank’s pH and nutrient levels. 

Since nutrition control is more precise when using coco coir, it’s possible to install a semi-hydro system with automatic watering. As with container growing, if you accidentally add too much fertilizer and are worried about salt buildup, the nutrients can be easily flushed out of the media, and you can start from scratch with your fertilization program. This feature also makes coco coir a good choice for beginners.  

To avoid salt buildup when using coco coir, the volume to drain ratio must equal 30% of the water/nutrient solution applied to the plant. For example, for every 1 liter of water delivered to the media, about 300 ml of water should drain out the pot’s bottom to leach away accumulations of salt.

Choosing a Quality Coco Coir Product

Just like the oil you buy for your car, not all coco coir out on the market is of the same quality. Coconut coir should be consistent from brick to brick, and salts should be leached out of the product during the production phase. If in doubt about the quality of different brands, confer with other growers on the best coco coir suppliers.

Like peat-based growing media, coco coir should be uniform in weight and shape. Ricococo World Wide, headquartered in Irving, Texas, with facilities in Sri Lanka, produces a consistent coco coir product from one bale to the next. This is due to the fact that they are one of the few producers who also own the production facilities. Also, Riococo’s smart infrastructure means they’re not impacted by the supply chain disruptions affecting virtually all other coco coir producers. 

Cannabis growers pride themselves on the substrate and nutrient mixes they create for their growing operations. In this article, we looked at suggestions for growing cannabis in coco coir. You will undoubtedly want to tailor your growing media and nutrient delivery system to your circumstances and personal preference. 

Coco coir is increasingly being used by cannabis growers not only because it is a renewable resource but because it offers an excellent medium to grow healthy root systems and, ultimately, large buds.