Molds and microbial testing for dispensaries and cannabis cups are now a new standard being adopted in various states and regions….. After the Emerald Cup 2015 we saw a huge rise in disqualifications due to chemical use or mold. Its not surprising to me but its def shocked the community at large. Take Colorado for example. They’ve had over 400,000 recalls over the last 6-8 months due to chemical use. And lets be clear the chemical use is due to the fact that no one knows how to control the problems that are arising and causing the actual problem. The indoor grows are not adequately designed to support the plants in a positive manner. To much heat gain on the leaf causing higher rates of transpiration. No fresh air from the outside because the fear of contaminants into the grow.. Plants would rather be outside than crammed inside a hostile environment.
Take greenhouses as another example. Indoor and outdoor growers are turning to greenhouses for a few reasons. The free sun is the main reason but also the protective qualities the greenhouse can provide are also attractive to growers. The one misconception is the greenhouse is like an extension of an indoor grow room… I might agree in the winter. Greenhouses were originally designed for winter and once the summer heat hits it becomes a different animal. In the winter we keep the greenhouse closed and use the light dep curtains as a energy blanket holding in heat and creating a double wall. Typically we add heat and lights as the main tools for winter time use. When the greenhouse heats up an exhaust fan or vent can be activated for a period of time. Once we get into summer the greenhouse needs to be able to take on another role. That role is to resemble more of an outdoor grow. “Summer Mode” as I like to call it means we are opening up the greenhouses to achieve passive ventilation. Greenhouses are designed to trap air and because of its transparent covers the air inside heats up.. We all know that in the heat of the summer we do not want the “greenhouse effect” or solar gain. In order to avoid solar gain we need to open the greenhouse either on the ends or with roll up sides and a roof vent. Trapping hot air in the summer is the last thing we need to be doing… Once we open the greenhouse the polyweave covers start to take over the job of protecting the p;ants from over exposure to the sun. You can read some of my earlier blogs on the diffused poly and how it works… However this is somewhat like an orchestra and your the conductor. Weather patterns aren’t as stable in the spring and fall so going from “winter mode” to “summer mode” can be tricky. Depending on how your greenhouse is set up it might be easy to roll down the sides or seal it up for the cold nights and then easily open again during the day. Once we get into the heat of the summer the greenhouses remain open all day and night. Trapping hot air is basically out of the question….
This brings me to my main point of molds and testing. The majority of growers/greenhouses are wrong. They are hostile environments and are generally not adequate for full plant support. which in turn leads to the problems. However some of these issues are not that visible to the naked eye and thats why entries are being submitted. Looks good, smells good but test positive…… Ouch!! What Ive come to realize is that the majority of greenhouses are set up in this manner….. Hoop or gothics with no roof vents and only roll up sides. The heat is still collected or trapped in the upper area of the greenhouse. The other misconception with the roll up sides are the exhaust fans running all day in conjunction with the sides up.. That doesn’t work to exchange air. Air exchange in greenhouses can only work efficiently and correctly if the sides walls, roof vents, doors are closed. Opening any of these breaks the seal and the fans pull from the path of least resistance. I see this combo way to much. Next we usually see circ fans aiming down. Hot air rises so why aim a fan downwards blowing the hot air back down where the cooler air tries to survive.. I also see oscillating circ fans around the perimeter of the greenhouse much like an indoor room and thats another bad idea. Oscillating fans help strengthen but you can have horizontal air flow fans do the same thing and more. I also see some other issues in this scenario. The greenhouse covers typically more clear or transmit to much light. More light transmission means more plant transpiration. More transpiration means more humidity in the greenhouse. More humidity during the day leads to problems. Pull a light dep cover over and you’ve just added the nail in the coffin. So lets review…. The wrong way to set up the greenhouse (any greenhouse) is to trap hot air in the summer by not having proper vents, to clear of cover, fans causing more problems and light dep at the wrong times. How do we fix it or set it up right?
First we need to avoid trapping hot air. In hoops I like to leave the end walls completely off. Heat rises and will find its way out the top of the end walls. Sometimes taking the end wall cover off for the summer is a better idea than trying to chop it up or modify. Also keep the side walls rolled up or fixed in the open position. Hoops with sidewalls up and end walls open will not trap hot air. The next step is making sure you have a diffused polyweave or polycarbonate. Cannabis tends to love the light but not the intensity. The diffused covers provide the protection these plants desire. If circ fans are used they can all be aimed in one direction to help evacuate any hot air that might be gaining due to the long hoops and thick canopy.. Aiming fans down will only confuse the air and the plants. Moving the air in a direction has a drying effect and Ive seen air temps drop a few degrees because the plants are the cooling system,.. Since they are made of water they are evaporative. Most people want to cool the air to mitigate surface temps but the process Im describing cools the surfaces without cooling the air. For the gothic and A frame greenhouses the roof vent is the key. Since hot air rises we can easily avoid trapping it by keeping the roof open. The principals are the same, avoid the heat gain, let the diffused cover to calm the suns intensity and have the fans aimed in the proper direction… All of these methods are important to pay attention to because the molds and positive testing are related to light dep/greenhouse grown material that is 99% there it just needed that extra level of consideration to avoid the problems.
My last point will be with UV. Im hearing a ton of growers attribute UV as the main reason for a better product. I hate to break it to everyone but you do not get UV through greenhouse covers. Even glass can block UV. When using these diffused covers we get zero UV. To be clear UVB in particular is the degrading and discoloring UV of all the rays. This also is why most people can spot outdoor over indoor or greenhouse. If you dont believe me then take this example… Outdoor plants typically do not get PM… or not very easily because UV breaks up that fungus. Indoor and greenhouses can get PM much easier because we have no UV.. Ive read a lot of books and talked to many people in the industry about hope UV makes plants better. I disagree to a point. We have been working with a analytical company to help prove these claims.