The addition of coir to a soilless growing medium may require some adjustment and monitoring of your crop production and cultural management practices. Depending on the percentage of coir in the growing medium, the following may need to be considered:

  • Water quality

    Know your water quality.  Due to the initial pH range of coir, the starting pH of a coir-based growing medium can be higher than the desirable range of 5.5 to 6.2. Over time, coir will contribute to rising growing medium pH, especially if the water source used has a high alkalinity and/or potentially basic fertilizers are used.  Monitor the pH of the growing medium so adjustments can be made to avoid pH increases that may reduce micronutrient uptake by the plants.

  • Adjust watering practices

    Peat-coir-perlite growing media will hold more water than peat-perlite growing media.  In addition, the surface of a coir-based growing medium will dry more rapidly than the root zone, compared to a peat-based growing medium.  Using the colour of the surface of the growing medium as an indication of when to water works for a peat-based growing medium but is less effective for a coir-based growing medium.  Growers must be attentive to not overwater crops in a peat-coir growing medium. This characteristic of the surface drying out quickly will often lead to crop growth issues from overwatering, especially in cool climates, high humidity, or cloudy conditions.

  • Nutritional balance

    Coconut husks naturally have high levels of potassium (K), chloride (Cl) and sodium (Na).  Although producers of horticultural grade coir products wash/rinse the coir to remove these and other compounds, they may still be high enough in a growing medium to elevate the EC reading.  With potentially higher levels of K, Cl and Na in a coir-based growing medium, measures should be taken to provide adequate levels of Ca and Mg for proper nutrient balance for crops. Initial fertilization rates may need to be adjusted upward when going from a peat-based growing medium to a peat-coir based growing medium to ensure the optimal levels of nutrients for optimum plant heath.