As the movement to legalize marijuana continues to take hold across the country, growers are beginning to seek out equipment that will help them maximize production. Many growers have turned to design-build contractors to provide cooling and dehumidification systems that help them maintain the temperature and humidity conditions needed for the various phases of marijuana grow operations. Did you know that growing temperatures should be kept at 77 to 80°F (25 to 26.6°C) to produce the largest yields while humidity must be tightly controlled during drying operations?

Until recently, no cooling and drying products were specifically designed to optimize marijuana growing conditions. Responding to the rise in indoor farming, technologies are being engineered to produce the right temperature and humidity conditions to maximize yield while minimizing mold and insect problems.

Using a systems-based approach, refrigeration equipment maker Century Refrigeration, Pryor, Okla., works with refrigeration equipment designers. The turnkey systems control both daytime temperature and nighttime humidity. The number and size of the units can be customized based on the refrigeration load. Systems can be tailored specifically to factors such as:

  • The number of grow lights.
  • The number of watts per light.
  • The amount of light infiltration.
  • The facility size.

Century has developed temperature control systems for operations with as many as 1,875 lights.

Marijuana growing operations begin with a veg room, where LED lights that do not give out a lot of heat are on for the majority of the day. The plants then are placed into bloom rooms equipped with custom-built, application-specific systems manufactured by Century Refrigeration. These rooms operate with lights that circulate on and off, a cycle that tells the plant it is time to bud. The plants are bloomed for approximately 56 days before being harvested and placed in a drying room, where humidity must be controlled both day and night. For ideal drying conditions, the rooms are kept at a constant humidity and 70° air temperature.

Century Refrigeration provided the custom circuiting and controls that are needed to maintain the required temperature differential (DT) for the application. Three different sizes of equipment are offered, depending on the size of the application. After many rounds of engineering, the company developed the custom-circuited coils and a line of condensing units.

The custom circuitry includes evaporator coils that provide the system dehumidification. The coils allow the system to condense water from the humidity and use the recovered condensate to water the plants. Using the recovered condensate water significantly reduces water requirements and costs and eliminates the need to purchase separate dehumidifiers.

Growers using a system with Century Refrigeration equipment report that crop yields have increased substantially compared to air conditioning systems, with zero loss to mold and spider mites.