This can be a hotly debated topic among growers as to what's the best media for growing plants. In this article, I'll weigh in with my opinion on the subject as there are Pros and Cons to both.
"Sphagnum" is a genus of approximately 120 different species of mosses known as "peat moss." Sphagnum and the peat formed from it do not decay readily because of the phenolic compounds embedded in the moss's cell walls. Peat moss can also acidify its surroundings by taking up cations, such as calcium, magnesium, and potassium, and releasing hydrogen ions. Under the right conditions, peat can accumulate to a depth of many yards. These bogs are slowly building and 80% of the peat moss used in the United States comes from Canada. Approximately .02 percent of the 270 million acres (422,000 square miles) of Canadian peat bog are used for peat moss mining. There are some efforts made to restore peat bogs after peat mining. It is debated as to whether the peat bogs can be restored to their pre-mining condition and how long the process takes. Many peat companies claim this to be a sustainable practice, but that is hotly debated topic depending on where you source your information on the subject.
Pros of Peat Moss:
Cons of Peat Moss:
Coco coir is the natural fibrous material found between the hard, internal shell and the outer coat of a coconut. It is treated before use as a growth medium for plants or fungi by soaking in a calcium buffering solution; most coir sold for growing purposes is pre-treated. Once any remaining salts have been leached out of the coir pith, it and the coir bark become suitable substrates for growing plants.
Pros of Coco Coir:
Cons of Coco Coir:
As you can see, it's not a black and white decision as to which growing media is superior. Personally, I prefer sphagnum peat moss because of the existing microbiology and the fact the pH is acidic, allowing for highly alkaline amendments like biochar and calcium in the form of ag lime and oyster shell flour. I've also had issues in the past with quality control on coco coir and heard horror stories of variability between batches from the same manufacturer containing high salinity. Regardless of what you choose, you'll most likely want to amend the media with pumice or perlite for aeration as well as some form of nutrients to improve fertility. I like to add earthworm castings or compost as well at a rate of 15-20% of total media to increase organic matter and biological diversity in the mix. If you want to read more about building soils you can checkout the blog post on 7 Important Things When Building a Living Soil.
I hope this article helped you form a more educated opinion on the subject. Happy growing!
*featured image courtesy of Aravind Sivaraj - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30743840