Professional Cannabis Cultivation

12) Flowering


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Lesson Summary:
In this lesson Cameron talks about what you’ll need to know during flowering stage of the Cannabis life cycle.


Lesson Transcript:

Hi everyone, I’m Cameron and today we’re going to be talking about flowering.

So when it comes to commercial cannabis cultivation, you want to mitigate your risks in as many ways as possible. One of the ways you can do that is by limiting the number of strains that you run in a particular flower room. At most I would say four strains is the maximum you want to run in a room, and you want to think about breaking that room into quadrants. So you’ve got four parts of the room, they’re all the same size, you’ve got the same number of plants, etc.

In terms of large scale commercial Cannabis cultivation there are different attributes for strains in terms of nutrient concentration requirements, total volume of water that’s required, so I look for commonalities among strains. So simply put: I generally think of nutrient concentrations as high, medium, and low, and I think of volume of water as high, medium, and low, so that gives us a total of nine potential variants. So I try to group all the same plants with high concentration and high volume of water in the same room at the same time. Similarly, I would do ones that want low concentration, low volume of water, whatever the mix is, just try and keep them together, run them through the system together, so we have predictable inputs and predictable outputs.

When feeding plants in a commercial capacity, we learn through trial by error. It’s usually going to take multiple iterations to find out which groups of plants should be grouped together to run through the system. Having said that, it’s not always going to perfect, and there’s always going to be some outlier strain. In terms of commercial cannabis cultivation, the outliers have to go away. If you pander to the outliers, you are instantly setting yourself up for failure.

As we move plants out of veg and into flower, we have hopefully already set them up correctly through the correct number of increments through the vegetative phase and the correct number of toppings, so we should have the correct number of tops, we should have the right number of plants. So as we lay them out on the tables, we have our sites already set up for us, we have our irrigators already set up for us, everything should be plug and play. Having said that, you are going to see some variation between plants even though we have for the most part removed the smallest plants. We’ve held back the biggest plants, and everything that’s left over comes out of this middle group. We will see variation even amongst that group. In that sense we want to create a coliseum sort of arrangement of plants with the tallest plants on the outside of the table with the smallest plants in the middle part of the table, and this makes it possible to limit the amount of shading that will go on. You put the tallest plant on the middle of the table you’re going to shade all the plants around it.

There is a process that takes place early on in the flower phase where we are pruning the plant in such a way that there is no wasted energy, there is no lost energy. So this process has a lot of different names, some people refer to it as skirting, some people refer to it as profiling, others refer to it as lollipopping. But it is basically removing the sort of smallest parts on the lowest branches, and that sends all the energyup to the top buds, or the top flower sites. So it is basically maximizing all of those flower sites that we’ve created through successive iterations of topping. We’re now concentrating all of the energy and all of the nutrients that are going to be taken up through the roots on those premiere sites, basically the top cola or the top two or three bud sites on each growing shoot. The next thing we do is we put the trellis down and set it in place and once the trellis is in place the plants aren’t moving anymore, the canopy is set and you’re basically off to the races.

When it comes to flowering, temperature and humidity are critical they become even more critical as the flower cycle continues, that is to say during weeks six, seven, and eight you’d never want to exceed 50% humidity and say seventy degrees (F). These are not hard targets. What I would say is when you’re setting up your room, spec the room, you want to ask for more than you need so you can get what you want. As these flowers develop they’re going to have this density to them, and high humidity can lead to catastrophic results when it comes to harvest. Week seven, week eight, if your humidity gets above 55% you’re going to be looking at a loss of a lot of your total yield through bud mold. You might not even see it when it’s in the flower room, but once you get it out of the flower room and into harvest and start drying you’re going to start to see big losses, and you’re going to see it in the form of like a black mold that starts to develop inside the flower, and you’re not going to see it until it’s too late. Basically what you’re going to lose are your best biggest buds are the ones that are going to be the most susceptible to this.

The way I like to spec rooms when I’m designing them is, let’s take a round number, let’s say we’re going to have a 3,000 square foot room and it’s going to have one hundred, thousand-watt lights in it. This room in terms of HVAC you’re going to want at least a half ton per thousand watts, so this room that’s going to have a hundred lights is going to need at least fifty tons of cooling. So once we have a baseline spec, we’ve got now one hundred lights and we’ve got a half ton of cooling per light, what I like to do is I like to bake in a little extra padding in terms of risk mitigation. So if I’ve got a hundred light room and we have specced at fifty tons of cooling, I might like to make my room sixty tons of cooling, that gives us a little more flexibility, a little bit more control than we might otherwise have. There are some parts of the country that are especially wet in the winter, or especially dry in the summer, and we cannot plan for all extenuating circumstances and so having padding in terms of these ventilation control and other controls for the environment are ways we can mitigate our risk.

Let’s talk for a minute about CO2 ,and if it gives you a competitive advantage in the commercial Cannabis space. The answer is a resounding yes, you absolutely want to be using CO2. Depending on the size of your grow, there are different ways you can go about it, you could have six-foot tanks, that would basically sit right here with me. They also have external 500 pound tanks, they sit outside the facility. Whichever way you’re going to do it, you’re probably going to want a service that comes in and fills these things up. It really depends on your municipality and whoever the CO2 provider is as to the best way to attack this problem, but tanks are usually the way to go. In some situations you might want a CO2 burner or a CO2 emitter. When it comes to CO2, the three options really are CO2 burners, CO2 tanks, or an external CO2 reservoir. The CO2 burners are sort of perpetual, and they run off a hard-wired gas line. The other two options it’s either small tanks being refilled or one large reservoir being refilled that feed the facility.

So on the flower side as we’ve already mentioned environmental factors are paramount. One of the ways we want to be thinking about designing the room is the way the air flows through the room. Cultivators like to have a “dead room,” that is to say as we’re filling the room with CO2 we don’t want that to be leaking out anywhere, however we’re really only using CO2 during the light cycle, so when the lights are off twelve hours out of every day, we are not going to be needing CO2 and we might need the ability to burp the room. So we want to be able to have fresh air come in from one side and exhaust on the other. Similarly, once the air is in the room and the lights are on and the day is running and we’re filling up with CO2 we’re going to have temperature differences and humidity differences at different levels in the room. It depends how high the ceiling is, it depends where your canopy is, it depends how much breathability you have between the canopy and the table top, so what we do is we have ways to mix the air in the room. One of the things we do is we create like a serpentine, a sort of snaking fan system along the roof. So we would have two fans pointing this way and then two fans pointing this way and then two fans pointing this way and we create an airflow that snakes along the top of the room. We also want to destratify the air in the room, so not only do we want the air mixing around this way, we also want the air mixing around this way. We can achieve that through similar to a mushroom fan that pushes the down in the middle and pushes the air up on the sides. I’ve done this through a charcoal filter with an inline fan blasting the air up. You set one in each of the four corners and you set this mushroom fan that’s blasting air down in the middle, and now what you’ve got is destratification in the corners, in the middle, and we’ve got this serpentine at the top of the room and now we’re mixing the temperature, and humidity and CO2in as many points as we really can, and that gives us more equal humidity and temperature at the canopy level and throughout the room.


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Course Notes:

Recommended Reading:
How to Grow Cannabis 151: Basics of flowering – Weeks 1-3
How to Grow Cannabis 152: The Basics of Flowering – Weeks 3-8


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