Ventilation for medicinal cannabis cultivation

The cultivation of cannabis for medicinal use has seen significant growth in the industry. This increase is due to the gradual legalisation of cannabidiol (CBD) cultivation in various countries, alongside the growing demand for medicinal CBD use.

Optimising cultivation conditions is essential to maximise yield and the quality of the final product.

Among the key elements in a cultivation environment, fans stand out for their contribution to environmental stability. The main functions of ventilation in the cultivation of these plants are:

1. Air circulation
2. Temperature control
3. Humidity control
4. Prevention of pests and diseases
5. Stimulation of vegetative growth

HIGH TEMPERATURES AND REDUCED GROWTH

Plant growth is closely linked to temperature control in their environment. When plants are exposed to excessively high temperatures, they stop growing as a natural defense mechanism. This protective measure allows them to survive in adverse conditions, though it compromises their development.

To ensure vigorous and healthy growth, it is essential to maintain air and root temperatures within certain optimal ranges. The ideal range for air temperature is between 26 and 28 ºC, while root zone temperature should be kept between 22 and 23 ºC. These conditions not only favour proper plant growth but also their ability to efficiently absorb nutrients and water.

TYPES OF FANS NEEDED IN CANNABIS CULTIVATION

There are many types of fans for this application, both for introducing new air (supply fans) and for extracting stale air and odours (extraction fans or exhausters).

• Axial fans: for extracting hot air and air renewal. There are more economical, low-power models, mainly used for supply.
  ➡️ HJEM, HJBM PLUS

And other more powerful and compact options, offering up to 40,000m³/h of airflow.
➡️ HJB

• Centrifugal and inline fans: for long and complex ducts due to the high pressure they offer, mainly used for extracting contaminated air and odours. They work more efficiently and quietly than axial fans, making them perfect for adding filters and long duct runs, though the selected fan needs to be oversized. Some models, like KUVIO and KUVIO EEC, allow for very easy maintenance without needing to intervene in the ductwork or unscrew them from the wall. Boxed options with insulation prevent the transmission of vibrations (BOX BD and BOX BD EEC). Another inline option without insulation, with an electronic motor, more economical but very efficient, is the SB-3 EEC. The non-boxed options, with external and reactive rotors such as BT-3 and BT-3 EEC, feature a sturdy sheet metal casing and are ideal for continuous use.

• Oscillating fans: to provide a constant and uniform breeze. Vortice Italia, a subsidiary of the Vortice Group to which Casals Ventilación belongs, offers a wide range of this type of fan.
  ➡️ NORDIK STORM, GORDON, NORDIK MIO, GORDON EVO.

In addition to fans, sensors will be needed to help control temperature and humidity, as well as speed controllers such as SFC (for three-phase fans), REGC (for EC motors), and REG (for single-phase) to adjust airflow intensity according to the specific needs of the crop (depending on the stage of the plant’s cycle) and timers.

The use of HEPA filters (High Efficiency Particle Arresting) like HEPAF and HEPAF2 in fans is becoming increasingly important to help keep the air free of contaminants, spores, and particles harmful to the crop. These are ideal for closed growing rooms and hydroponic systems. In extraction, activated carbon filters, such as CAF and CARF, are used to eliminate odours and volatile organic compounds (VOCs).

MAIN FUNCTIONS OF FANS IN CANNABIS CULTIVATION

1. Air circulation
Fans help maintain proper air circulation in the growing space. This circulation is crucial to prevent the formation of stagnant zones where air can accumulate moisture, fostering the development of mould and other fungal diseases. Additionally, fans can be combined with specific CO₂ generators to accelerate photosynthesis and plant growth.

• Benefits: Improves the distribution of carbon dioxide (CO₂) and other volatile nutrients, essential for photosynthesis.
• Recommended practice: Use oscillating fans or continuous circulation fans to maintain a constant airflow.

2.Temperature Control

Fans help regulate the temperature within the cultivation area, preventing extreme spikes and drops that could negatively affect plant development.

• Benefits: Prevents overheating and provides efficient heat dissipation generated by grow lights.
• Recommended practice: Combine fans with cooling systems or air conditioning to maintain stable temperatures.

3. Humidity control

Maintaining the proper humidity is crucial to prevent diseases such as mould and rust. Fans help reduce humidity by promoting the evaporation of excess water in the air.

• Benefits: Reduces the risk of fungal infestations and other pathogens that thrive in humid environments.
• Recommended practice: Use dehumidifiers alongside fans to maintain optimal humidity levels, generally between 40% and 60%.

4. Prevention of pests and diseases

An environment with good air circulation and controlled temperature is less prone to pest and disease problems. Fans help keep pathogens at bay by reducing humidity and the accumulation of spores in the air.

• Benefits: Decreases the likelihood of infestations by mites, whiteflies, and other insects that can damage plants.
• Recommended practice: Implement an integrated ventilation system with HEPA or activated carbon filters to purify the air.

5. Stimulation of vegetative growth

Air circulation induced by fans can help strengthen the stems and branches of plants, making them more robust and less prone to falls or mechanical damage.

• Benefits: Promotes more vigorous and healthy growth, improving the plant's overall structure.
• Recommended practice: Set fans to provide a light, constant breeze, especially during the vegetative phase of cultivation.