How Transitioning from Coco to Stone Wool Substrate Improves Cultivation Efficiency

Many cannabis cultivators who want to change the type of substrate they use hesitate because they’re concerned about the perceived challenges or operational interruptions of such a big shift in their cultivation methodology. But transitioning from one growing medium to another doesn’t have to be disruptive - and the rapid production gains and long-term savings make it well worth the effort.

When transitioning from coco to stone wool substrate, for example, growers not only see benefits with their resource utilization during the growing cycle, they can also reduce overhead costs and required labor. It’s also easier to implement more efficient growing strategies such as crop steering or automation that further enhance efficiencies from planting to harvest.

While moving from one growing medium to another does require some extra work at the outset, it saves on labor aspects in the long run in a head-to-head comparison of coco vs. stone wool.

Coco, like other substrates that consist of small particles of organic material such as potting soil, can produce a lot of dust. Combined with the humidity and moisture endemic to indoor cannabis cultivation environments, a little dust can quickly become a big problem. Keeping cultivation facilities clean is imperative to keeping pests under control - particularly microbes and pathogens. By utilizing a clean and inert substrate like stone wool, staff can focus on plant maintenance instead of facility maintenance.

Not only do inert substrates like stone wool reduce the overhead costs associated with facility hygiene, they also improve efficiency in other ways. Because stone wool is inert, it doesn’t contain any contaminants or nutrients beyond what cultivators introduce. In contrast, when you start with coco there’s an element of the unknown: Any organic material will have residual nutrients from its own growth or decay cycle.

Coco in particular can be high in salts even after processing, requiring more preparation work and flushing with water to reach the baseline ideal for cannabis cultivation.

Substrates like coco are also highly absorptive, which means they hang on to water and fertilizer that could otherwise be absorbed by the cannabis plants they’re intended for. This retentive quality makes it harder for cultivators to pivot on the precise delivery of water and nutrients as the cannabis plant moves from the vegetative to flowering phases.

Stone wool, on the other hand, not only has a neutral pH balance, it also has a very low cation exchange capacity (CEC). Simply put, the CEC is a measure of how molecular particles in the growing media are charged and bind to one another. A low CEC means that fewer molecules bind to one another over time. Therefore, stone wool doesn’t hold onto nutrients but instead makes them available to crops.

That low-level CEC lends itself to crop steering techniques as well. Cultivators practicing crop steering pivot their delivery of light, water and fertilizer in carefully targeted ways depending on where the cannabis plant is in its growth cycle. For example, juvenile cannabis plants need different nutrients and irrigation capacity than plants nearing harvest.

The extra time it takes to change water and nutrient levels might not sound like much, but the ability to reduce a crop cycle by a few days or even a week can make a big difference to an operation’s bottom line. Triggering the crop’s hormonal shifts through rapid media refreshment ultimately translates to major labor and resource savings.