Using Coco Coir Grow Fiber in THDC Vertical Hydroponic GrowTube™ Systems

 A variety of grow media materials can be fitted into THDC GrowTube™s including coconut coir, synthetic wool, PET recycled fiber, etc. For many installations, coir is a superior grow media with the following advantages:

  • Coconut coir is an organic, bio-degradable fiber that is totally environmentally friendly and has naturally evolved as a superior hydroponic grow media – it is light weight, never shrinks, cracks or produces crust.

  • Plants started in coir peat can be directly transplanted into grow tubes without using other media. Coir's soft structure allows plants to develop strong root structures through easy penetration and healthy growth.

  • Coir has excellent drainage and provides great aeration even when completely saturated - air circulates through the root zone even when wet so roots remain healthy.

  • Coir has a very high water retention capacity and a longer drying time than many synthetic fibers – Coir holds up to eight times its weight in water and loses it very slowly so plants are protected from power outages and water flow can be very regulated to save electricity.

  • Coir has a high lignin to cellulose ratio that helps slow its rate of decomposition. It has a life of 3 to 4 years.

  • Coir has an ideal pH range of 6-6.7 and has a very low EC.

  • It is largely inert and with time develops a high buffering capacity that helps plants overcome a short term fluctuations in nutrients and water chemistry.

  • It has a high cation-exchange capacity (CEC) - the grow media has a higher capacity to hold nutrient cations and a larger nutrient reserve. It is able to hold and release nutrient elements according to the plant’s needs and the prevailing conditions in the medium itself.

  • Contains significant amounts of natural nutrients phosphorous (10-50ppm) and potassium (150-450 ppm), which are essential major plant nutrients.

  • Coco coir has natural anti-fungal properties that help protect plants from soil borne diseases. It inhibits pathogens like Pithium.

Preparation and Nutrient Considerations

  • New, untreated coir may contain high levels of potassium, chloride and sodium salts that are best flushed and buffered before use.

  • Coir contains natural levels of potassium and sulfur that need to be compensated for in the nutrient solution used in the system.

  • Concentrations of nitrate, potassium, magnesium and phosphorus may increased in coir media over the grow cycle and need to be compensated for in the nutrient mix.

Signs of Toxicity

  • Slow/stunted growth

  • Yellowing

  • Burning

  • Rusting on edges of leaves

  • Rust spots on leaves

Flushing and Buffering Coir Fiber

To Flush coir fiber strips with Tap Water

  • Installed coir fiber strips into the grow tubes

  • Use a large container like a barrel

  • Measure the EC of the mains water

  • Place the grow tubes with installed coir fiber strips in the barrel

  • Circulate the mains water through (flush) the coco fiber strips until the EC of the water that has passed through the coir (runoff) equals that of the original EC

  • Remove the grow strips and empty the tap water

  • Fill the barrel with distilled (RO) water and dilute the buffer concentrate to 1.4 EC and pH adjust to 6.0

  • Place the grow tubes with installed coir fiber strips into the diluted buffer solution and leave to circulate

  • After circulating, remove the grow tubes and stand to dry

Measuring Coco Coir pH

  • take fiber samples from around the root zone, mix these with distilled water (1:5), then test with a pH meter.