What is Peat Moss?

Sphagnum (Peat Moss) is a genus of approximately 380 accepted species of mosses, commonly known as peat moss. Accumulations of Sphagnum can store water, since both living and dead plants can hold large quantities of water inside their cells; plants may hold 16–26 times as much water as their dry weight, depending on the species. Peat moss can also acidify its surroundings by taking up cations, such as calcium, magnesium, and potassium, and releasing hydrogen ions.

Pros of Peat Moss:

  • Free of weed seeds, pests and pathogens.
  • Can absorb up to 20 times its weight in water.
  • Contains beneficial microorganisms.
  • Acidic pH (a “pro” in my opinion because you can add highly alkaline amendments to it).
  • Contains a variety of elements, especially sulfur, which helps with proper terpene expression.
  • Excellent habitat for beneficial microorganisms.
  • Harvested in North America, which reduces the fossil fuel impact to get it to the United States.
  • Holds 10x to 20x its dry weight in water.
  • Better C:N ratio than coco coir.
  • Cation exchange capacity (CEC) of 100-200.

Cons of Peat Moss:

  • Depletes peat bogs, which requires them to be re-built or sustainability harvested.
  • Naturally hydrophobic, meaning if allowed to dry out it will be slow to accept water.
  • Needs to be kept evenly moist for optimal plant growth and health.
  • Requires hydrating before use.

What is Coco Coir?

Coco Coir or coconut fiber, is a natural fiber extracted from the husk of coconut. Coir is the fibrous material found between the hard, internal shell and the outer coat of a coconut. It is usually treated before used as a grow medium for plants or fungi by soaking in calcium buffering solution. Most  Coco coir is sold for growing purposes has been previously treated. Once the remaining salts have been leached from the coir pith, it and the coir bark become suitable substrates for growing plants.

Pros of Coco Coir:

  • Coir pH usually runs 6 – 6.7.
  • “Renewable” resource – byproduct of the coconut industry.
  • Easier to rewet than peat moss, is not hydrophobic.
  • Usually cheaper than peat moss.
  • Different reports list coco as having a water capacity ranging from 8x to 30x it’s own weight.
  • Excellent habitat for microorganisms.
  • Free of weed seeds, pests, and pathogens.
  • Breaks down slower than peat due to high lignin content.
  • Cation Exchange Capacity of 40-60.

Cons of Coco Coir:

  • High salinity unless properly washed.
  • Quality can vary depending on batch and source of material.
  • Higher fossil fuel cost to get the coir to the United States from tropical regions.
  • Does not contain many trace elements.
  • Does not contain microorganisms.
  • Traditionally high in sodium and potassium which can lead to calcium or magnesium deficiencies unless properly treated.
  • Requires hydrating before use.
  • Increased incidence of nasobronchial allergy among workers in this industry due to the high amount of dust created.
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