The terms coco coir and coco peat are often used interchangeably. Both materials originate from the fibrous outer husk of the coconut, but they represent distinct components of the processed husk. Coco coir correctly refers to the coarser fibers. Conversely, coco peat, or coir pith, is the fine, dust-like byproduct that remains after the fibers have been removed. Understanding the physical and chemical differences between these two materials is important for successful use in horticulture.
Defining Coco Coir
Coco coir, also known as coir fiber, is the fibrous material found between the hard inner shell and the outer green layer of the coconut. The process of separating this material from the husk is often initiated by retting, where the husks are soaked in water to soften the fibers.
The resulting material is composed of thick, stringy fibers that are inherently coarse and durable. In gardening, coco coir primarily refers to this longer, structured material, which is often chopped into chips or used in its long-strand form. This fibrous nature means that coco coir is used to impart structural stability and improve air-filled porosity in growing mixes.
Defining Coco Peat
Coco peat, also called coir pith, is the fine, spongy material left over after the coarse fibers have been extracted from the coconut husk. It consists of the dust and short, powdered particles generated during fiber processing. This material has a texture similar to traditional peat moss, which is the origin of the “peat” designation.
Coco peat is often compressed into dense bricks or blocks for efficient transport and storage. It is chemically and physically distinct from the coarser fibers, possessing a much higher surface area. Although it is a byproduct of the same husk, its unique composition makes it function differently in a growing environment. Coco peat exhibits a slightly acidic to neutral pH range of 5.5 to 6.5, which is suitable for most plants.
Functional Differences in the Garden
Coir fibers and chips are prized for their ability to maintain structure and enhance drainage in potting mixes. They create large air pockets that ensure excellent aeration, which is important for root health and preventing waterlogged conditions. This makes the fibrous coir an ideal component for media requiring high porosity, such as orchid mixes or soil amendments for heavy clay.
Coco peat, conversely, is characterized by its superior water retention, capable of holding up to eight times its weight in water. This high water-holding capacity is due to its fine, sponge-like structure, making it effective at replacing peat moss in soilless growing media. Coco peat has a high Cation Exchange Capacity (CEC), meaning it can temporarily hold onto and exchange nutrient ions with plant roots. A blend of both coco peat and coir fiber is often used to achieve an ideal balance of water retention and aeration for general potting mixes and hydroponics.
Preparation Before Planting
Both coco peat and coco coir require preparation before planting due to their origin. Coconut palms often grow near saline coastal areas, and the husks are sometimes processed using brackish water. This leads to elevated levels of sodium and potassium salts. If these salts are not removed, they can cause nutrient toxicity or stunt plant growth, which is measured by a high electrical conductivity (EC) level.
The first step is typically a thorough rinsing or leaching with fresh water until the EC of the runoff water drops below a safe level, ideally under 1.0 mS/cm. After this initial wash, a process called buffering is often necessary, especially for hydroponic applications. Buffering involves soaking the material in a solution containing calcium nitrate to displace potassium and sodium ions bound to the coir’s exchange sites. This ensures the material does not “lock out” essential nutrients like calcium and magnesium from the nutrient solution, preventing deficiencies in the growing plants.