Peat Moss vs Coco Coir: Which is Better for Cannabis Grows?

You’ve probably heard the term peat moss before or have seen it listed as an ingredient in pre-mixed soil bags. Peat moss, otherwise known as sphagnum, is a mixture of mosses that some cannabis cultivators use as a substrate or soil amendment. Chances are you’ve also seen or used coco coir, another, more popular soilless growing medium made from the processed husks of coconuts. In this Rx Green Technologies article, we’ll walk you through exactly what peat moss and coco coir are, how they’re made, and the pros and cons of using each in the garden as substrates for your cannabis plants.

What is Peat Moss?

Peat moss, which is technically “sphagnum” or “sphagnum moss”, is the commercialized name for a genus of over 380 different species of mosses that have special qualities which make them useful in certain scenarios for cultivating all kinds of plants, including Cannabis sativa. Contrary to popular notions, when you purchase a bag of peat, it isn’t just a single type of moss; it could be one, or more likely a blend of many different kinds that fall under the sphagnum umbrella, because they have a specific cellular structure compared to other species of mosses. They’re an interesting type of plant because they form together in massive clumps, do not produce seeds or flowers, and importantly, are non-vascular (more on this shortly).

An example of a sphagnum moss’s cellular arrangement under a microscope

Sphagnum mosses have special characteristics that allow them to hold as much as 26 times their dry weight in water and are highly resistant to decay despite living in moisture-rich environments. Over hundreds of years, they alter their surroundings and are known to scientists as “autogenic ecosystem engineers.” In addition to its decorative uses for florists and as a soil amendment for cultivators, peat moss has been used for centuries to help dress wounds up (through World War I) because it is highly absorptive, while also exhibiting anti-fungal and anti-bacterial properties. In northern regions, it has also served as an insulating material for dwellings since time immemorial.

How is Peat Moss Made?

Although a variety of areas across the globe, from southern Chile to Norway have abundant wetland zones of sphagnum mosses, virtually all of the world’s commercially sold horticultural peat moss is harvested from bogs in Canada. While peat moss does grow in the United States, western Canada’s prolific high-moisture, temperate rainforests, largely in British Columbia, are the primary region where it is harvested (or “mined”). There isn’t much to it: the peat is extracted from certain types of bogs, aka peatlands, then undergoes a screening and blending process, and is finally bagged for sale. Very few cultivators, cannabis included, use straight peat moss as a soil substrate; instead, it is typically mixed with other things such as perlite, minerals, and mycorrhizae.

One of the biggest ecological drawbacks to peat moss is its perceived lack of sustainability and environmental impact. Biologists have discovered that natural peat bogs take centuries to form, leading many conservationists to call for sharp reductions in peat moss harvesting. Most sources we searched indicated that only around 0.03% of Canada’s total peatlands have been affected by peat moss mining activities, but the real issue is whether or not those harvested areas can truly return to their original state. Another issue is that even tiny losses in peatlands can release large amounts of CO2 into the atmosphere, as peat bogs contain an astounding 44% of all soil carbon, exceeding that of all the world’s forests by a large margin.

There is such a thing as peatland restoration, but it takes decades to occur and has been noted to result in much more monoculture colonization, so whether or not peat is legitimately a sustainable product is still largely up for debate. That said, thankfully, it only affects a small percentage of the available landmass in Canada.

What is Coco Coir?

Coco coir, or simply coir in certain cases, is one of the world’s most popular soilless growing substrates for cannabis and is derived from the natural fibers of coconut husks. In fact, there are two types of coco coir; brown coir, which is what most of us are familiar with and is sourced from ripe coconut husks, and white coir, which is made from unripe coconut hulls and is useful for finer thread options like fishing nets, brushes, and certain kinds of rope. Brown coir, which primarily originates from Southeast Asian countries such as India, the Philippines, and Indonesia, is what we’ll be focusing on in this article. Brown coco coir is also what many cannabis growers prefer as their base growing medium due to its ability to offer plants highly customized nutrient regimens.

Coco coir has been used for thousands of years because its fibers are durable, biodegradable, and highly absorbent in horticultural applications. Coco can be susceptible to certain types of pathogenic fungi, so selecting a high-quality source is critical. Because coco coir contains high amounts of lignin and low amounts of cellulose, it tends to be stronger and less flexible than other kinds of fibers, but importantly, imbues coco coir with moisture-holding properties that are ideal for cultivators. However, before it can be used in your garden, it has to undergo a special cleaning process to ensure it’s ready for plants.

How is Coco Coir Made?

Horticultural coco coir is made by first stripping mature coconuts of their husks and then soaking the husks in water to swell the fibers. It is then washed to remove dirt, debris, and other organic detritus. It’s important that if you’re purchasing coco as a cannabis growing substrate that you either get pre-buffered coco or buffer it yourself before planting in it. Buffering is an extra step that involves soaking the coco coir in a calcium and magnesium solution, which further enhances its overall quality for growing in, as this technique helps prevent overly high levels of salts and nitrates from being present from the start of each planting cycle. Without the buffering step, coco tends to have very high levels of salts, which is not what you want to try to grow your highly valuable cannabis plants in. It also improves the coco’s cation exchange capabilities, which further enhances nutrient uptake.

After buffering, coco coir is fully dried and packaged into bales for further compression, often into blocks that will then be processed further elsewhere. Notably, coco is a truly sustainably sourced growing medium since it is a byproduct of coconuts, and does not require ecological damage to produce.

While not all suppliers take the steps we do to get it ready for your garden, at Rx Green Technologies, we’ve literally searched the world over to find the best sources of raw coco coir. When coco arrives at our production facility, it’s just the beginning of its manufacturing journey, not the end. In our specialized process, the raw, compressed coco blocks are first tested for quality, and are then shredded, filtered, hydrated, mixed, tested again, and packaged as either 2 ft3 bags of loose coco or into our popular Ready To Use coco grow bags. To learn more about how we make our premium quality coco growing products, check out the video below.

Peat Moss vs. Coco Coir for Cannabis Cultivation: Pros and Cons

Now that you have a good idea of exactly what peat moss and coco coir are, as well as how they’re made, we’ll break down the factors you need to consider for your cultivation activities before selecting a medium to plant in.

Peat Moss Pros and Cons for Cannabis Growing

Pros

• Best in class moisture retention
• Lightweight for shipping purposes
• Adequate nutrient retention
• Essentially sterile growing medium

Cons

• Higher latent acidity with a natural pH of 3.0 – 4.0
• No intrinsic nutrients
• Rarely used as a standalone growing medium, must be mixed
• Requires lengthy rehydrating periods to be useful
• Questionable harvesting sustainability

The Bottom Line: While peat moss offers some attractive qualities for cannabis cultivation, it is more of a niche soil substrate, and offers its best use case in very arid greenhouse or outdoor applications, such as those in the Southwestern U.S. Its best use case is as an additive to other soils or soilless mixes.

Coco Coir Pros and Cons for Cannabis Growing

Pros

• Good balance of moisture retention and draining capabilities
• pH-neutral foundation for fully customizable nutrient regimens
• Great aeration properties for root zone development
• Can be used alone or mixed with amendments of all kinds
• Sustainable, environmentally friendly growing medium
• Excellent composition for the needs of cannabis plants

Cons

• Can be susceptible to microbial growth
• Unbuffered coco can leach salts
• Requires pH level maintenance
• Sourcing high-quality coco and be difficult

The Bottom Line: coco coir is the cannabis industry’s go-to soilless substrate for a reason: because it’s highly versatile, easy to amend, and offers terrific aeration for root development. While it does require regular feeding and pH regulation to perform at its best, coco is usable in all growing environments and locations.

Peat Moss vs. Coco Coir Conclusion

There are always going to be growers who swear by one thing or another. Peat moss as a cannabis cultivation substrate tends to fall into the category of specialty use in most cases, whereas coco coir offers excellent versatility and is much more popular in general. Its superior characteristics enable growers to get the best of all worlds: moisture retention that can still drain well, high aeration properties for root development, and fully customizable nutrient schedules to meet the specific needs of certain strains. If you’re ready to start using coco coir in your grow or are looking for an affordably priced supplier that cares as much about quality as your cultivation team, contact one of our experts today to learn more about how Rx Green Technologies can help you cut costs and boost your profit margins.