Since the inception of the cannabis industry, the market has shown no sign of slowing down. As demand continued to grow, so did the call for higher-quality cannabis. As a wise man once said, “growing cannabis is easy; getting it right is the real challenge,” and exactly here lies the essence of the job of the cannabis grower.
Because the goal is to ‘get cannabis right’, it is not surprising that cannabis operations globally resort to the most advanced horticultural technology and solutions: the purpose is always to grow the highest-quality cannabis.
Where to start?
When one starts thinking about the best cultivation methodology to use, they are confronted with many different systems, each with its own pros and cons. But with the exception of nutrient film technique, aeroponics, and deep water culture, growers always need to select a substrate. When it comes to this, there are a few things to keep in mind.
"A poor choice of substrate has drastic consequences on the results of the crop. The substrate is not only the medium where the roots of the plant grow but also its sustenance and its source of nutrients", explains Juan Manuel García, agronomist at Projar, specialized in high-yield substrates for cannabis.
"The roots need a substrate that provides firmness and nutrients to feed strong and productive plants. The development of the roots is essential for the plant to develop fully and with generating an abundant result. But everything has to start by taking care of the roots" Garcia continues.
Selecting the substrate
Generally speaking, there are a few factors that should drive such a decision: easiness of use, sustainability, cleanliness, and cation-exchange capacity. This last concept is particularly important for the selection of the substrate, as it measures the extent to which the substrate retains the minerals contained in the nutrients that are fed to the plants.
"High-quality coconut fiber is an incredible substrate for the development of the cannabis plant due to its air-water balance that allows a broad development of the roots and, consequently, of the plant” explains García. “It is a 100% natural substrate that derives from the valorization of a residue from another industry and also once the crop is amortized it’s an easily manageable waste”.
Its composition of different sizes provides optimal water retention and optimal oxygenation for the root system and thus guarantee an effective development of the crop avoiding waterlogging and its derived problems.
Roots require oxygen to maintain their metabolic activity and growth. A temporary deficit of oxygen can reduce their growth and also the growth of the aerial part, but hypoxic conditions maintained for several days can cause the death of some roots.
Cation-exchange capacity is generally highly present in all those substrates that are natural, like coco coir for instance, while artificially made media, such as rockwool, have either very little or no cation-exchange capacity at all.
Let’s take rockwool, for instance. This is a very simple growing medium to use, and also exceptionally lightweight, making it very easy to carry around. However, rockwool is definitely not environmentally friendly at all: plugs need to be substituted after every cycle, leaving growers with the burden of disposing of the used plugs, which comes at a cost, not only in terms of money but also in terms of environmental toll. Last, rockwool has little to no cation-exchange capacity.
A substrate with Cation Exchange Capacity acts as a desalination plant for sodium, that allows the use of medium-quality water and also savings in drainage water. In addition, we could avoid quality problems derived from difficulties in the absorption of potassium, calcium or magnesium if CEC is in a moderately large range.
And now the nutrients
Thus, according to the type of medium selected, it is important to adjust the nutrient schedule, and here comes the tricky part. The nutritional needs of a plant might change according to the growth stage it is at; but generally speaking, potassium is one of the substances that plants consume more during the flowering phase. It is then critical to deeply understand the genetics one is growing so as to know what the nutritional needs over their entire life cycles.
At the end, the key is to combine the chosen growing media with a proper fertigation management.
"At Projar we not only sell substrates and cultivation solutions. But we accompany our clients in their business from an agronomic advisory point of view" explains Alejandra Pintos, the company's Marketing Director. "Working in so many countries and with so many cultivation cases allows us to have a very extensive knowledge and to know-how to advise our clients on how to optimize their results with agronomic strategies focused on their specific needs".
"We have developed a portfolio of products for the different growing phases of Cannabis, based in all cultivation technologies (indoor, outdoor, greenhouse) that growers can download at this link."
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