How To Water Coco Coir


As coco coir grows in popularity many growers are asking how to water coco coir? In this article we’ll dispel some common myths about watering in coco coir.


Myth #1 “You Can’t Over Water Coco Coir”

Many growers choose coco coir as a substrate due to it’s comparatively high air to water ratio. Given this, is it still possible to overwater coco coir? The answer depends on its quality and consistency.

To keep costs low many well-known coco coir brands are increasing the amount of coir dust in their product. These companies are blending coir dust with larger grades of coco coir for mixes that hold a certain amount of water. Much of this water this water remains trapped in the dust and unavailable to the plant. Under a certain size, coco coir particles are too small to properly distribute air and water for optimal plant growth. When water is added to the fine coir dust it develops a muddy, anaerobic consistency.

Drybacks slow and water is less available to the roots. Moisture removal becomes almost completely dependent on the environment, adding to the workload of HVAC systems. This volume of oxygen-depleted water suspended in coir dust accumulates towards the bottom of containers, creating the perfect conditions for pathogens such as pythium. 

Coco coir blended with dust absolutely can be, and often is, over watered – especially in automated systems. The Riococo manufacturing process removes any material smaller than 4mm, including all fine dust. We blend these larger particles create Riococo PCM grow bags: a mix which which maintains an air to water ratio of 28%-33%,  a volumetric water content of 53% –  and a is virtually impossible to over water.


Myth # 2 “Coco Coir Should Always be Watered Until Runoff”

Some growers are watering coco coir multiple times daily with enough nutrient solution to achieve 20%-30% runoff after each event. This usually won’t cause any problems with the cannabis plants (at least not when using Riococo).However, it is a waste of water, nutrients, and money.

Riococo recommends a fertigation program designed to achieve 15%-20% runoff. Growers calculate this percentage with the total volume of daily irrigation and the total runoff volume – not individually for each cycle. Once plants are established growers won’t see much, if any, runoff until midday. Once the pot is refilled to capacity, irrigation cycles maintain this volume and can act as micro-flushing events to stabilize ph and EC in the root zone. After runoff is seen, it increases in cumulative volume after each cycle until the last event of the day. 


Myth #3 “Coco Needs to be Flushed”

When Cannabis growers measure a high runoff EC after watering coco coir they typically decide to flush the medium. These high readings are likely the result of either industrial buffering practices or high sodium levels – common in many brands of cannabis-specific coco coir. Corrective flushing is achieved by pouring large volumes of water or watered-down nutrients through the pot until more acceptable EC/pH readings from the runoff are seen. This is seldom practiced by growers outside of the cannabis industry.

Riococo believes the only time growers should be flushing is at the end of a flowering cycle. We minimize sodium levels in our coco coir by only using coconuts sourced from the Sri Lankan interior. Riococo does not buffer our coco coir, allowing growers to control the medium EC from start to finish. Riococo PCM coco coir allows growers to maintain their desired EC levels from the start. No more fertilizer, water, or time flushed down the drain.


Ready to see for yourself how Riococo can help your facility save on labor and increase yields? Request a quote today!