It is easy to make mistakes when planning a new facility or upgrading to large-scale production. Many cultivators have gone through the process of building a facility only to discover later that a mistake was made and that the systems, methods and environmental controls are not compatible. When this occurs, business owners are forced to expend massive amounts of time and capital on a do-over. A multitude of factors need to be considered when designing a facility, and ample opportunity exists for missteps. The decisions you make will often dictate your fiscal success or failure. To avoid costly mishaps, here are important factors to consider when planning or designing a grow.
1. Employee Decontamination Areas
All persons entering the facility must change attire. Street clothes and shoes must be replaced by regularly cleaned work clothes that are free from pests and diseases. After changing, the employee should further decontaminate his or her feet (by walking through hydrogen peroxide and foaming agents) and hands (by submerging in disinfectant) prior to entering any cultivation area. Plan for proper decontamination zones, or risk having outside pests and diseases tracked into the grow rooms.
2. A Sealed Environment
As of late, I have seen many growers building greenhouses with direct access to the outside environment, meaning they open a huge door, and their plants are immediately and directly exposed to the elements. A completely sealed environment is preferred in commercial operations. Why would it be any different for cannabis? The more controlled an environment is, the easier it is to prevent or minimize infestations.
3. Greenhouse Coverings
There have been many recent greenhouse cover advancements, but beware: Not all coverings are created equal. A covering that does not inhibit ultra-violet (UV) light transmission is vital. Coverings that inhibit UV light transmission are detrimental to THC production. Diffused light that still allows proper light spectrum is equally important. When choosing which covering to employ, convey all required parameters to the manufacturer.
4. Positive Air Pressure
Positive air pressure must be created in both indoor and greenhouse environments. It should not be an afterthought. A positively pressurized environment assists in detouring infestation of both pests and diseases because the air exiting the doors or vents at an increased velocity makes it difficult for pests and pathogens to enter. Most commercial greenhouses are positively pressurized, utilizing filtered and sterilized air. Again, why would cannabis be different?
Many growers have initially underestimated the equipment or size of the equipment required to achieve proper airflow. For both indoor and greenhouse environments, proper airflow is a roughly 1.5-mph breeze (or 132 feet per minute). A perfect balance is easily achieved through:
- A constant airflow that promotes proper CO2 dispersion and eliminates the possibility of air stagnation, humidity rises or oxygen depletion;
- Proper equipment to move air through the facility; and
- A consistent pruning technique to remove lower branches and unnecessary vegetation.
Additionally, an even distribution of all incoming air is preferred. To ensure this, greenhouse growers typically utilize inflatable ventilation ducts under their grow benches that expand to cover the entire length of the greenhouse.
6. Air Filtration and Sterilization Capabilities
All incoming air must be filtered by utilizing commercial High Efficiency Particulate Air (HEPA) filtration or other commercial filtration methods. Cultivators must also utilize either UV air sterilizers or electronic air sterilizers. By filtering and sterilizing all incoming air, contamination risk is minimized. Greenhouse growers should look to bug netting as pre-filters to mitigate pests of specific sizes.
7. Humidity and VPD (Vapor Pressure Deficit) Control
Growers who underestimate their dehumidification needs or size of their dehumidification equipment put their facility at risk of a powdery mildew or gray mold outbreak. Along with proper airflow, air dispersion and supplementation with CO2-humidity control is a very important factor in proper environmental control. Plants transpire substantial amounts of water every day, so you must have the ability to control humidity levels at all times, day and night. Consult with an HVAC technician for indoor situations (or a greenhouse designer) prior to construction to state your intentions, plans, size and requirements so they can design to suit elevated humidity environments.
You must also incorporate the ability to control VPD. VPD is the difference between the amount of moisture in the air and how much moisture the air could potentially hold when it is saturated, as defined by Michigan State University Extension. Once air becomes saturated, water will condensate to form dew or films of water over leaves. A perfect balance of both humidity control and VPD is a big part of productive, healthy plant growth and flowering.
8. Expansion Plans
If you plan to or think you might expand your business in any capacity, it makes sense to plan ahead for such an eventuality. By doing so, you get to imagine the overall picture, envisioning everything from logistics to workflow. Then you can refine and change the plan before you begin and possibly prevent wasting valuable resources constructing something you either regret-or at the very least, wish you had planned better. Laying out the design well before build-out allows time for reflection on your desires and goals, and how to best accomplish them.
When I first met a commercial tomato greenhouse grower, I asked why he chose the location of his greenhouse. He immediately pulled up a computer program that showed where it would essentially be both cheapest to heat and cheapest to cool the greenhouse. He also factored in proximity to market, supplies and qualified labor. You must consider these and a multitude of additional factors regarding location (besides whether or not you can legally grow there).
10. Resource Availability
Many suitable locations for cannabis cultivation have been rejected for insufficient power availability, water availability or disposal reasons. Do your homework on the location before expanding or purchasing. Some growers have entered into real estate agreements and paid large sums of capital to municipalities and brokers, only to receive a letter from an agency such as the Public Utilities Commission informing them that the power promised to them did not exist.
Check out the May issue of Cannabis Business Times for 10 more important considerations for facility design, especially those related to cultivation and workflow.