What is Coco Coir?

Coco Coir gets talked about a lot, but what exactly is coco coir?

Between the hard external coat and internal coat of coconuts is a fibrous region called the coir. The fibers are pale when the coconut is young and turn brown and harden with age. White coir from young coconuts can be used to make rope and fishnets. Mature brown coir can be used to make brushes and floor mats. Coir fibers are very water-resistant, and can even resist damage from saltwater. 

Coir pith, coco peat, coir dust, or more simply coco coir, are synonymous with the powdery waste product resulting from processing brown coir fiber. It is washed, heat-treated, then screened and graded before being packaged in compressed bricks for retail sale for horticultural use. The granularity and density will vary by brand but despite some variability in texture, physical, and chemical properties remain similar. Coco chips from the coconut husk and brown fiber are not generally used as a soil conditioner but are sometimes used in a soilless medium for hydroponics and growing epiphytic plants like orchids. It is not generally used alone but makes a good replacement for peat moss since it has better nutrient and water retention properties. 

Coco Coir Nutrient Considerations

“Cocopeat” was first written about in 1949. The short fibers and dust from coco pith were found to be a good growth medium for plants. Coir pith is soaked in a calcium solution to be treated before it is used in horticulture. Coir is naturally high in sodium and potassium so it is necessary to leach the salts out to prevent magnesium or calcium deficiencies in plants. Due to the naturally high potassium salt levels, coir pith may need micronutrient fertilization to amend levels of calcium, sulfur, copper, and iron. Supplementation of magnesium is also highly recommended. A slow-release fertilizer can be added to ensure stable nutrient levels are maintained.

Coir is Capable of Immobilizing Nitrogen!

Nitrogen lockout can be an issue if the coir pith is not fully decomposed at the time it is used for planting. To avoid the risk of nitrogen deficiency in plants, it is important to use high-quality coco coir from a good source. Poor quality coir may also not be properly treated to leach out excess salts and require additional washing. To check the quality of the coir, electrical conductivity can be measured. 

Using Coco Coir

In comparison to peat, coir pith has less air space, but unlike peat, the air space does not degrade over the course of the plant growth cycle. Coir pith also has a higher water-holding capacity and can hold about 1000 times more water than soil. Unlike peat, coir also re-wets with ease after being dehydrated and is easier to prepare for use.

Seeds sown in 1:1 coir-perlite medium have been observed to establish larger root systems than seeds sown in 1:1 peat-perlite soilless growth medium. The addition of coarse sand to add weight and dolomitic lime to increase calcium and magnesium is beneficial when using coir. Coir may also be mixed with soil and compost for planting.

Coir is not suitable for use with all plants due to its pH which ranges from 5.5 to 6.51. In hydroponic applications, it can be mixed with perlite. Such a system has shown to increase yield and plant quality in plants like roses. You can see the properties of coir compared below:

Physical Properties of Coco Coir (Coco Peat; Philippine Sourced)

  • Bulk densities 0.04 to 0.08 g/cm-3
  • Air-filled pore space 9.5% to 12.6%
  • Water-filled pore space 73.0% to 80.0%
  • Total pore space ranged from 85.5% to 89.5%
  • Total solids 10.5% to 14.5% of total volume
  • Water-holding capacity 750% to 1100% of dry weight
  • Significant differences in particle size distribution depending on the source may range from <8.0mm and 0.25 to 0.50mm

Chemical Properties of Coco Coir (Coco Peat; Philippine, Sri Lanka, Indonesia Sourced)

  • pH 5.6 to 6.9
  • Electrical conductivities 0.3 to 2.9 mS/cm-1
  • Fe, Mn, Zn, B, and Cu at 0.01 to 0.07mg/L-1
  • NH4-N and Mg 0.1 to 0.2 and 1.0 to 7.4 mg/L-1
  • Ca, Na, and NO3-N levels ranged from 1.0 to 24.3 mg/L-1, from 22.3 to 88.3 mg/L-1, and from 0.4 to 7.0 mg/L-1 depending on the source
  • Wide range in K (19 to 948 mg/L-1) and Cl (26 to 1636 mg/L-1) depending on the source
  • Cation exchange capacities ranged from 38.9 to 60.0 meq/100 g depending on the source

Coco Coir Fungi and Bacteria

Coir is highly susceptible to the greenhouse fungus Leucocoprinus, so care must be taken to monitor for signs of the fungus when using coir mediums in greenhouse conditions. Coir is also susceptible to other fungi which can be pathogenic to plants, so be sure to check it over before using, store it properly, and purchase from a reputable source.

There is some claim that Mexican coco coir contains beneficial fungi that may repel pathogens, but little research has been done to confirm. In general, coir from a reputable source will be free of pathogenic bacteria and fungi. Purchasing high-quality coir is important to avoid these risks, and value brands should be avoided. 

Coco Coir Benefits and Precautions

Coir is a known allergen and may also contain traces of the allergen latex which may be used in processing. Caution should be taken by individuals with allergies or sensitivities to coconut or latex. As long as you are aware of the particulars of coir, it can be a great growth medium that offers many benefits! If you are looking for where to buy coco coir, Hortitech Direct has many coco coir growth medium options available.

Benefits of Coco Coir Growth Medium (Cocopeat)

  • Better water retention than peat moss
  • Equal or better drainage than peat moss
  • Generally free from pathogens, fungi, and weeds
  • Does not degrade as quickly as peat moss
  • A renewable and sustainable product that makes use of waste byproducts
  • Easier to re-wet than peat moss
  • pH, electrical conductivity, and cation exchange capacity are acceptable for use with most plants, especially if mixed with other mediums to balance acidity and amended to balance nutrients
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