What to do when retrofitting a greenhouse for medical cannabis cultivation

In recent years, cannabis cultivation has increased considerably, mainly due to the legalization of its medicinal use in several countries. The cultivation trend continues to rise and many are joining this business opportunity by retrofitting existing greenhouse facilities.

Inspection of the infrastructure
To adapt an existing facility to the cultivation of medical cannabis, the first thing to do is to evaluate the initial state of the greenhouse. “First of all, it is important to assess the condition of the structure,” says Amir Abbas with J.Huete, a company specialized in high-tech agricultural projects. “So, the starting point is to carry out a complete revision of the structure and change or repair what is necessary.” Since cannabis growing has different requirements than more ‘traditional’ horticultural crops. “For this crop, it is necessary to have separate areas for each of the phenological stages,” Amir continues. “Which means, one area for plants in the vegetative stage, another for flowering plants, and another area for clones and mothers. Most likely, the facility needs additional internal partitions with separate access doors for each newly created zone.”

Then, Amir says the last check on the infrastructure should be on the cover materials. “If the cover is a plastic film and it is necessary to change it, the new plastic must have anti-condensation properties. The same applies to the ventilation meshes, and if they have deteriorated, they should be replaced with new ones, of course.”

What about the equipment? 
Once the assessment of the infrastructure is cleared, it is time to take a look at the equipment. “Depending on the cultivation methodology, there are several things to look at,” Amir explains. “When it comes to irrigation, irrigation heads should be checked and adapted if necessary, especially if we are talking about soilless cultivation – with substrates, that is. In that case, the irrigation system should be adapted in such a way as to be able to perform precision fertigation. Growers could also use drainage collector gutters: in this instance, it will be necessary to channel the irrigation drainage to take it out of the greenhouse to maintain humidity and hygiene conditions stable. This will allow the drains to be reused if required.”

Since cannabis plants are photoperiodic, the greenhouse has to be able to accommodate that. “Depending on the environmental conditions of the area where the greenhouse is located, a shading, energy-saving, or mixed screen will be installed,” he says. “On top of that, if necessary, photoperiod screens can be installed to induce flowering and control this fundamental phenological stage. All of this can be supplemented with some artificial lighting: this allows to achieve the necessary light hours, which also ensures maximizing photosynthesis and therefore the production and synthesis of cannabinoids.”

But then, the growing environment is the top priority, and with that comes controlling the temperature. “The cultivation of medical cannabis requires temperatures that can range from 15 degrees Celsius to  30 degrees Celsius, depending on the cultivar” Amir points out. “For this reason, it is possible that during the coldest months of the year, it is imperative to increase the temperature, especially during the first and last hours of the day. Increasing the temperature also helps to control excess humidity.”

And indeed, humidity is a huge aspect. “Relative humidity requirements vary from 50% to 70%, depending on the genetics,” says Amir. “To increase RH, high pressure or low pressure misting systems can be installed. On the other hand, dehumidifiers can be used in the event RH levels get too high.”

All of the aforementioned couldn’t be control if it weren’t for climate control systems. “To correctly control and monitor all the parameters, we will need a climate controller that is capable of controlling all the equipment. In addition, all kinds of sensors must be installed to control temperature, relative humidity, radiation, PAR radiation, heating water temperature, CO2 concentration, and so on,” Amir concludes.

For more information:
J.Huete 
jhuete.com 


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