Coir has become a favored option for cannabis cultivators around the globe due to its ease of use in fertigation, feeding, and overall management.
Coir fiber, coir pith, and coir chips/chunks are the primary horticultural products available. Below, you will find a table with the distinctions among these three subproducts and their compatibility with cannabis plants.
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Coir Fiber |
Coir Pith |
Coir Chunks |
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Natural fiber derived from the outer husk of coconuts. It is frequently utilized in the production of items such as ropes, brushes, fabrics, and coir mats and is limited for applications in growing media. |
Coir pith is a material that binds the coconut fiber within the husk, giving it a spongy texture. It is obtained by taking out the lengthy fibers. |
These particles have distinct characteristics that enhance water retention, aeration, water flow, and stability in the growing media. |
When choosing coir substrates, it's crucial to use a checklist to ensure quality assurance from the coir supplier. Key factors to consider:
High energy consumption and water usage are crucial factors in the production of manufactured coir. It is essential for companies involved in coir as a growing medium to share a commitment to sustainability and environmentally friendly practices.
PRO-MIX® is committed to environmental conservation and community support at our Sri Lanka factory, working towards a sustainable future. To achieve this, we follow third-party certification protocols, reduce our ecological footprint, and foster innovation while ensuring sustainability in our products.
Coir serves as a sustainable growing medium that not only supports the environment but also facilitates post-harvest plant disposal. Its ability to retain water boosts plant resilience to environmental stressors while minimizing water and nutrient leaching, thus preventing plant deficiencies.
If you include coir in your soilless mix, you may need to adjust your crop management and watch your plants closely. The percentage of coir in the growing medium can influence the following factors:
Understand the quality of your water. Coir's natural pH level can result in a coir-based growing medium having a starting pH above the desired range of 5.5 to 6.2. Coir can increase the pH of growing media over time, particularly if the water used has high alkalinity or if basic fertilizers are applied.
Keep a close eye on the pH of the growing medium to make adjustments and prevent pH increases, which can hinder the plants' ability to absorb micronutrients.
If the pH or E.C. meter utilized to analyze the sample features a cup or small reservoir with the electrode positioned at the bottom, it is essential to extract the water or solution from the growing medium sample. This applies to samples prepared with the S.M.E., 2:1, and potentially the 5:1 testing methods.
To obtain the solution, place your growing medium sample into a coffee filter and squeeze it, allowing the solution to flow through the filter. You can then test this solution for pH and electrical conductivity (E.C.). For both the pour-through and squeeze methods, the extracted solution from the growing medium is sufficiently clean, meaning no further filtration is necessary.
If the pH and E.C. meters are pen-style or equipped with probes, they can be directly inserted into the "mud" formed by the S.M.E., 2:1, and 5:1 testing methods. However, it is important to note that many pH and some E.C. probes feature a glass exterior that can be easily scratched by perlite, pumice, and other abrasive materials. If this poses a concern, it is advisable to extract the solution from the growing medium as previously mentioned.
Table 1. Test Methods.
| Test Method | Test Sample Is... | Solution Extraction Required From Sample? |
| S.M.E | Saturated medium, like mud | Yes |
| 2:1 | Watery mud | Yes |
| 5:1 | Mostly solution, with some mud | Maybe |
| Pour-Through | Clear Solution | No |
| Squeeze | Cloudy Solution | No |
Table 1. Test Methods
Once the sample is ready, it's time to assess the pH and electrical conductivity (E.C.). Before utilizing a pH or E.C. meter, ensure they are properly calibrated. If they are not, the readings obtained will be inaccurate, and any adjustments made to the crop culture to address an issue may jeopardize the crop.
pH Results
The standard pH range for different crops, as shown in the table below, is applicable to all methods of testing growing mediums. The sole exception occurs when the growing medium solution is extracted from a Soil Moisture Extractor (S.M.E.), using a 2:1 or 5:1 sample with a vacuum. This extraction technique may raise the pH of the solution by 0.2 to 0.5 pH units.
| Crop | Low pH | Ideal pH | High pH |
| Calibrachoa, Dianthus, Diascia, Nemesia, Pansy, Petunia, Snapdragon, Verbena, Vinca | <5.2 | 5.4-6.2 | >6.4 |
| Ageratum, Alyssum, Chrysanthemums, most herbs, Impatiens, Lantana, Lobelia, Osteospermum, Poinsettia, Torenia, most vegetables | <5.5 | 5.7-6.2 | >6.5 |
| Geraniums (zonal), Lisianthus, Marigold, New Guinea Impatiens, Pantas | <5.6 | 5.8-6.5 | >6.8 |
Table 2. pH by crop.
2. Modify your watering methods.
Compared to peat-perlite growing media, peat-coir-perlite growing media retains more water. Coir growing mediums experience quicker surface drying compared to their root zones, a contrast to peat-based mediums. The color of the surface of peat-based growing media can reliably signal when to water, but the same method is less effective for coir-based growing media. Peat-coir growers should avoid overwatering their crops. Quick-drying surfaces are prone to overwatering problems for crops, especially in cool, humid, or cloudy climates.
3. Nutritional balance
Coconut husks are naturally rich in potassium (K), chloride (Cl), and sodium (Na). While coir products are washed to remove impurities, these compounds might still be present in sufficient quantities to cause a higher EC reading in the growing medium. Elevated potassium, chlorine, and sodium levels in coir-based growing mediums necessitate the addition of calcium and magnesium to maintain optimal nutrient balance for crops. To achieve optimal plant health, you may need to raise initial fertilization rates when switching from peat to a peat-coir blend for growing.
Coir is an excellent growing media that can be combined with perlite or used as a pure coir formula. It retains water, allows for proper drainage, promotes aeration, and facilitates quick root growth.
Our focus at PRO-MIX® is to work closely with growers in order to create a meticulously balanced blend that addresses concerns such as rapid drying or excessive water retention. Before introducing our coir formulas to the market, we extensively tested and utilized our formula for cannabis plants. Our goal is to utilize facts and R&D to create a dependable growing media that guarantees consistency in every cannabis facility.
