Coco Coir vs Peat Moss
By Katherine Placzek
Dear reader,
This article began initially with a straightforward trajectory. I was going to lay out why using peat moss in soil mixes is environmentally harmful and that we all should make the switch to using coco coir. But as I continued my research, I found it was not that simple and the subject required lots of continued digging to find accurate information. Instead, I am going to try to educate you on both substrates to the best of my ability.
Peat Moss:
Why is it used:
Peat moss has an incredible water retention capability- holding 20 times its weight in water. It also has a small but not insignificant amount of nutrients. You can pot a plant directly in peat moss and it will grow due to these nutrients. It is light and fluffy, used by many gardeners to lighten existing soils. It is highly acidic if not amended with lime, and shrubs like hydrangeas or blueberries can successfully be planted into peat. It also can be used as a pea/bean inoculant. It was not until the 1970s that peat became commonplace as a planting substrate for plant people.
How is it harvested/manufactured:
Peat bogs have centuries (possibly more) worth of plants and decomposing peat/sphagnum peat growing and compacting in a dynamic cycle and ecosystem. It is estimated that peat bogs contain more than 44% of all the Earth’s soil carbon and thus are considered a carbon sink (where carbon is stored and absorbed from the atmosphere). Harvesting practices vary in different bogs and countries. The majority of the peat sold in the United States is harvested in Canada. 95% of all peat in Canada is harvested in partnership with the Canadian Sphagnum Peat Moss Association (CSPMA). The CSPMA has strict regulations that they follow, and are involved in many ecological restorations, as well as scientific research behind peat bogs, and the living organisms that use the bogs as habitat. Many of their practices publicize that they attempt to reduce harm, prevent overharvesting, protect habitats, and replant as part of their aim toward sustainability. While this sounds good, in 2021, it was reported that peat harvesting released 2.1 megatonnes of carbon dioxide into the environment. That’s the equivalent emissions of the annual emissions of five gas-fired power plants. Critics also point out that rehabilitated peat bogs are unable to become a carbon-accumulating ecosystem (or a carbon sink) until roughly 20 years after harvesting. Harvesting in other countries is not regulated and they are likely not as concerned with any harm associated with their practices. All harvesting is mechanical due to utilizing fossil fuels. The UK has banned all peat sales for personal gardens beginning in 2024.
Factors to consider:
- Peat bogs house diverse and intricate habitats for all sorts of living organisms. Harvesting, regardless of practice, disrupts this environment.
- Peat bogs are considered carbon sinks- absorbing carbon from the atmosphere. Harvesting peat releases carbon into the atmosphere, causing concern that this practice contributes to climate change.
- Fossil fuels are used in the harvesting process and are used in the shipping of this product to garden centers and other plant/ home improvement stores.
Coco Coir:
Why is it used:
Coco Coir also has a high water retention rate, retaining 8-9 times its weight in water. It does not have any innate nutrients or pH implications, so it is a neutral starting point as a substrate. Coco coir is a waste product from all other food-grade products made from the meat/ milk of the coconut. Before the 1980s, millions of tons of coco coir were left to decompose in large piles, often taking close to 20 years to decompose. Now there is a market for this “waste product,” as a soil substrate.
How is it harvested/manufactured:
Many coconut plantations are based in the poorest countries, Sri Lanka, India, Vietnam, the Philippines, and more recently, in Central and South America and even Mexico. Coconut plantations are often monocultures that reduce natural biodiversity and cause displacement of living organisms. Coconut trees produce a lot of coconuts but do so at the cost of soil degradation. The coconut hull first is soaked in water (freshwater or saltwater) for a long time to break down the fibers on the hull. This process is called retting. The retting process generates water pollution. Among the major organic pollutants are pectin, fat, tannin, toxic polyphenols, and several types of bacteria including salmonella. While scientists are experimenting with treatment options, there does not seem to be a broad-scale accepted solution at this time. This wastewater is often returned to the local community’s water supply or the ocean. Then, either the coconut hulls can be highly processed through mechanical mastication, or beaten and broken down further by hand. This manual process creates a lot of dust, and workers are typically not provided any PPE (Personal Protective Equipment). Reports indicate an increase in respiratory illnesses in communities with coco coir processing. Many of the following processes, if mechanized, are achieved with fossil fuels. There are currently no regulations on the industry’s standards. I also found conflicting information on whether a second rinse with chemicals is necessary, so that is an additional set of pollution outputs to consider. In general, it’s harder to find reputable sources explicitly sharing information about coco coir. This makes me concerned about the transparency of the industry, as well as possible offenses that are intentionally hidden from the public’s knowledge.
Factors to consider:
- Many coconut plantations are monocultures, created by destroying native habitats for diverse organisms, thus causing soil degradation.
- Pollution of the environment due to wastewater from retting processes.
- The lack of regulations concerning this product allows for humanitarian abuses to occur, including health hazards for workers and the surrounding community.
- Fossil fuels are used in portions of the manufacturing process and in transporting this product to your local garden center.
I think continuing to use coco coir or peat moss warrants extra research. Dig into the companies that you are supporting. Do they have certifications, and third-party ratings that indicate that they care about their staff’s health and wellbeing? The environment and the community they impact? Their carbon footprint? Other points that you are passionate about?
All of this makes me consider, there have been gardeners and plants people before me who did not have access to these substrates. What did they use before? Compost. Manure. Leaves. Green manures/ cover crops. Aged forest products (humus). Straw. None of these probably have the water retention that peat moss or coco coir boast, but they all have higher nutrition, which means prior plants people did not have to fertilize in the same manner that we do when we utilize a peat or coco coir base. Many of these local inputs are also free. All of this is interesting and will lead to further research on my part.
The most honest conclusion that I can make is that, when we are removed from the product we are buying, we also become naïve of the ultimate cost and any negative impacts of the product. Perhaps, the point here is to grow plants that are acclimated to our growing habitat (for instance, native plants do not need peat or coco coir to thrive), or to build soil from what nature provides in our local vicinity. While this is easy to say, it is harder to do. I think this new knowledge is powerful, though. We can always experiment and try new things in hopes of finding replacements that have a lesser negative impact. Good luck with your own decisions ahead of you!
Soils that we carry that do not contain peat moss or coco coir:
Back to Earth-
- Composted Cotton Burrs (Acidified and Non-acidified)
EKO-
- Clay Buster
- Top Dressing
Happy Frog-
- Soil Conditioner
Rocky Mountain Soils-
- Top Soil
- Humus
- Compost Cow
- Tree and Shrub
Yard Care-
- Soil Pep
Note: We also carry a variety of only coco coir or only peat-based soils, if you decide you prefer one over the other.
Resources to utilize in your own research:
I think that Gardener Scott (A gardener in CO, who has an excellent library of YouTube videos on vegetable gardening) has a comprehensive video on the pros and cons of both of these substrates.
The link to the website that Gardener Scott references: https://www.gardenmyths.com/coir-ecofriendly-substitute-peat-moss/
Canada’s National Observer on the carbon footprint of peat harvesting: https://www.nationalobserver.com/2023/07/07/news/canadas-carbon-storing-peat-digs-climate-dilemma#:~:text=According%20to%20Environment%20Canada%2C%20about,of%20growth%20within%20those%20sites.
21 report on carbon sinks and greenhouse sources in Canada: https://publications.gc.ca/collections/collection_2023/eccc/En81-4-2021-1-eng.pdf
A Q&A with the Canadian Sphagnum Peat Moss Association (CSPMA):
The CSPMA’s website (includes the history of peat, how their manufacturers harvest peat, industry reports, and more) https://peatmoss.com/
Generalized information on how coco coir is made: https://www.madehow.com/Volume-6/Coir.html
Another source on how coir is made: https://coir.com/utility/how-to-make-coconut-coir-the-manufacturing-process/
A study linking coco coir to impaired respiratory function: https://www.thepharmajournal.com/archives/2023/vol12issue3/PartAR/12-3-455-522.pdf
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