In the previous issue of Cannabis Culture, we interviewed a veteran Canadian commercial marijuana grower named BC Hardcore, and visited several of his commercial grow houses (CC#47, BC’s million dollar grow shows).
In that article, we explained how commercial growers maximize security and yield by using clever risk-avoidance techniques, and by retrofitting and enhancing electrical systems of regular houses so that the houses become hundred-light cultivation factories.
This installment of our commercial grow series explains the revolutionary Closed Growing Environment (CGE) method, which allows growers to create indoor microclimates ideal for plant growth while also enhancing grower security.
CGE is used by the best commercial growers, but CGE techniques are useful for all growers. Even small-scale cultivators may be able to benefit from adopting some of these methods.
In an ideal CGE grow operation, all ballasts, electrical plug-ins, air conditioning, and other equipment are sequestered in rooms that do not contain plants. This keeps unwanted heat and equipment out of plant rooms, decreases electrical dangers, and increases maintenance flexibility.
Some growers place air conditioning units, ballasts, and other electrical equipment in rooms specially designed to control electrical hazards, while placing nutrient reservoirs, propane tanks and related equipment in other segregated, non-plant rooms.
CGE eliminates problems caused by exchanging air with the outside world. One air exchange problem happens when cannabis produces heady odors due to evaporation of volatile terpenoids; these odors, when dispersed out of the grow room, can alert police and rip-offs.
Non-CGE growers spend lots of money on ionizers, ozonators, and other devices to prevent odor vectoring to the outside world, but CGE is the most cost-effective, efficient odor control method because it does not allow air to escape the grow environment.
The CGE method also eliminates problems caused when untreated outdoor air brings insects, fungi, spores, molds, and even hemp pollen into a grow room.
When BC Hardcore builds CGE grow rooms, his teams install major venting systems consisting of aluminum and sheet metal vent pipes connected to air conditioning units and outfitted with activated coconut carbon charcoal filters that have the size and tubular appearance of a 40-gallon hot water heater.
Such filters eliminate odors and pathogens; the charcoal in them should be replaced every four to eight months. Growers recommend locating charcoal filters at the top of a grow room so they are easily connected to venting systems, and because warm air rising in the room often carries with it the most pungent odor particles.
Some growers use ionizers and ozonators for odor and disease control, but Hardcore insists that these devices are not especially useful, especially in large rooms.
Ozonators come in two types: ultraviolet ozonators which work best in rooms with up to seven lights, and electrical corona ozonators that are installed in air venting in larger grow rooms. Although ozone generators are useful for killing spider mites, spores, fungi, and powdery mildew during down time between crop cycles, they’re also hard to maintain, are not 100% effective in reducing odors and pathogens, and, for human safety reasons, are not recommended for use during crop cycles.
Hardcore favors charcoal filter odor control, augmented by in-line fans that are big enough to exchange all the air in the room in an hour. Instead of bringing air in from outdoors, the fan and carbon filter clean the air in grow rooms, or in a separate “mixing” room, and put clean air back out into grow rooms for plants to breathe.
Feed the breeze
CO2 augmentation is necessary in a CGE environment because air is recirculated, instead of having fresh CO2-rich air brought in from outdoors.
CO2 augmentation is useful in most indoor grow environments, even non-CGE environments, because CO2 speeds plant growth. However, when CO2 is used in rooms that are not properly sealed, the gas can cause health hazards, and is partially wasted when it escapes the grow room instead of being totally absorbed by plants.
CO2 is easily provided by tanks, but tanked CO2 is very expensive compared to that provided by CO2 generators which burn propane or natural gas. (When Hardcore uses propane CO2 generators he uses 100-pound propane tanks instead of smaller tanks to avoid having to do a lot of refill work.)
The use of tanked CO2 can facilitate the killing of spider mites and other pests. In true sealed grow rooms that have no leaks, growers can kill all pests by upping CO2 levels to 10,000 parts per million (ppm) for one hour. Other CO2 augmentation methods are incapable of generating 10,000 ppm for an hour ? only the tank supply method is capable of providing that concentration of CO2. Especially when using 10,000 ppm bug-killing tactics, growers must use safety methods that minimize the health problems that CO2 can cause for humans.
The burning of propane or natural gas produces pure CO2, but also produces heat and humidity, which can stifle plants. Excessive heat inhibits plant intake of CO2. Growers seeking to avoid adding heat and humidity to grow environments sometimes put their CO2 generators outside the grow rooms and use fans to send CO2 from the generators into rooms via duct systems. CO2 generators used in rooms should be hung above the lights; to increase CO2 dispersion, several small generators should be used rather than one large generator.
CO2 stimulates plant growth, but must be circulated to the underside of leaves where plant transpiration takes place. Plants do not utilize much CO2 during dark cycles, so CO2 controllers should be set to decrease or stop the flow of CO2 when grow lights are off. The keys to successful use of CO2 augmentation are good air circulation and maintenance of adequate CO2 levels.
BC Hardcore uses CO2 sequencers and controllers that measure air density and then turn the CO2 devices on and off to maintain a 1,500 ppm CO2 level in the rooms. CO2 units that can generate 26-38 cubic feet of CO2 per hour are generally adequate to maintain 1,500 ppm when used in pairs in rooms that have 10-20 lights.
Hardcore recommends having wall mounted fans above the lights, and also at a height about two feet below the lights. He also likes to have CO2-rich air pushed into his rooms via intake fans, with exhaust fans on the other end of the room pulling the CO2 through the plants.
Most CGE growers use sensors to monitor air and other factors to ensure an ideal growing environment: 73-78?F (23-25?C) temperatures, 40-55% humidity, 1,500 ppm CO2, constant air flow and aeration, and scrubbed air.
Some sensors can be equipped with remote monitoring and notification features so that growers are notified by pager if their grow room environment has slipped out of optimum. When combined with computerized interface and cross-links to security systems, growers can instantly find out what’s happening to their grow room from almost anywhere in the world.
Obviously, large commercial grow rooms depend on industrial-strength air conditioning (A/C) units.
Hardcore says it’s relatively easy to calculate A/C needs. Air conditioners are rated by a “BTU” cooling capacity per ton; they are rated at 12,000 BTUs for every ton of cooling capacity. Each 1,000-watt HPS light in a CO2-augmented room requires about 3,500 BTUs of cooling to maintain a target ideal growing temperature of 78?F (25?C). For every 1,000-watt light in a non-CO2 grow room, growers need about 2,800 BTUs of cooling capacity.
These formulas can be downsized by 10% if light ballasts and CO2 generators are located in a central room outside the grow room.
In some commercial houses, growers use five-ton water-cooled air conditioners; a five-ton A/C unit provides 60,000 BTUs of cooling.
Other growers use “split” air conditioners that have a compressor outdoors and the cooling A-frame indoors. An A-frame split air conditioner uses air to cool the Freon and compressor, while water-cooled air conditioners use water for this task.
Water-cooled units are less noisy: they don’t have a fan and compressor running outside the grow house, as often occurs with a split five-ton. Water-cooled air conditioners use five gallons of water per minute, so people who rely on wells or other insufficient water supplies can easily run out of water.
Water companies monitor usage on behalf of drug warriors, and even if drug warriors aren’t monitoring water usage, the water bill can be very large. That’s why commercial growers often use above-ground swimming pools to store and recirculate water for water-cooled units. Some growers also lower their water bills by drilling holes in the water-measuring paddles of water meters.
The water-cooled A/C preferred by Hardcore is an “active” system that uses a compressor and Freon. So-called “passive” systems cool by running water through a coil that air is blown over, and they are less expensive to use.
For every three 1,000-watt lights, growers should use one 16-inch oscillating fan. Along with the obvious benefits of increased air circulation, fans blowing on plants will force thicker stalk development, which will create better nutrient circulation, healthier plants, and increased yield.
In some circumstances, it might be necessary to pull moisture out of the air to maintain ideal humidity between 40-50%. Dehumidifiers with drain systems offer one solution, but Hardcore prefers to outfit his air conditioner units so they also function as dehumidifiers.
He installs a heater core in an A-frame cooler inside the grow room. As the A-frame air conditioner runs it dehumidifies the room and is also cooling the room at the same time. The heating core is necessary because the cooling unit will keep on cooling as it dehumidifies, which can drop room temperature below 78?F (25?C). The heating core boosts temperature back up to 78?F (25?C) and also helps dehumidify rooms more efficiently because warmer air holds more moisture.
During the initial build-out of a CGE grow room, carpenters wait until insulation, venting, and electrical work is complete before they build plywood grow trays that are three to six feet wide. The trays are coated in plastic or fiberglass, and drainage is built in. Hardcore emphasizes that plant trays or pots should not sit directly on floors. Floors are usually cold, and root temperature has big effects on plant health and growth. Elevating roots so that they stay warm is very important.
Hardcore has experimented with all types of grow mediums, from rockwool to expanded clay pellets. He advises growers to use Sunshine Mix #4 (a sphagnum moss/soil combination) because it is relatively inexpensive, easy to find, porous, and natural.
Commercial growers almost always use clones. Some growers build their own mother and cloning rooms, but most buy clones for between two to 10 dollars apiece from clone factories.
Hardcore and other commercial growers note that clones are one of the primary vectors for plant pests and diseases. Clones and clone factories should be rigorously inspected before growers buy clones and bring them to their final grow destination. Hardcore brings a magnifying glass, microscope and pathogen test kits to examine clones, clone mothers, grow medium, nutrient water, and the general grow environment.
He is very alert to even the most minor indicators of disease or pests. These include stippling, spotting, yellowing, curling or darkened areas on leaves, as well as more obvious signs of infestation, such as the thin white webs created by spider mites.
If there is any sign that clones are infected with plant pests, Hardcore says the clone seller should spray the clones with a regimen of pesticides, like Advanced Nutrients “Genius Oil” or “Bug Away.” The grower should revisit the clone factory in five days and examine the clones again.
While it is possible that infested clones might be made safe by spraying, clones that exhibit plant diseases early on can probably never be made right, and should be absolutely avoided.
“Never bring sick or infested clones into your grow,” Hardcore warns. “If mites, thrips, gnats, molds or mildews get in there, there will be hell to pay when you try to get them out. I would rather delay starting a new veg cycle, or even go to the trouble of using seeds, before I would buy a batch of suspect clones.”
If you find healthy clones, place them directly into soil beds, or in three to five-gallon pots, spaced 15-20 per light. If the rooms use automated watering systems, they are outfitted with spaghetti line fed off a hose with one-inch header no-drip emitters. Growers use valves to adjust flow levels on each feed. Nutrient solutions are stored in large, sterilized plastic barrels; sophisticated, flexible, pump-timer plumbing systems are used to get water from reservoir rooms to plants.
In rooms that are functioning properly, with plants metabolizing at max levels in ideal temperature and humidity, plants need water every two or three days. If you over-water, you literally suffocate your plant’s roots.
In all commercial grow houses I visited, growers were using Advanced Nutrients products, but one grower had reservoirs containing General Hydroponics (GH) nutrients alongside his Advanced Nutrients reservoirs. He tested GH FloraGrow, FloraBloom and FloraMicro against Advanced Nutrients Sensi Pro Two Plus formula. The GH nutrients gave him 1.2 pounds per light with “Jamaican clones.” The Advanced Nutrients Two Plus program gave him 1.9 pounds per light with the same type of clones.
Growers cited ease of use and increased bud weight and resin production as their reason for using Advanced Nutrients products. All the commercial growers who provided access for this article use Advanced Nutrients Final Phase to flush plants during the last week of flowering. They also use the company’s Wipeout formula, along with two hours at 10,000 ppm CO2, to kill mites and other problems between crops.
Even if you are only a hobbyist or small med-pot grower, the lessons of commercial cultivation should not be lost on you. A CGE commercial grow house is like a spaceship, with currents of clean, enriched air flowing across the brightly-lit leaves of healthy, happy plants grown in aerated, fertilized soil. Quality control and security are built in, so spider mites, diseases, rip-offs and other invaders never penetrate the glowing plant chambers.
“When you drive around Vancouver, you can bet that every fourth or fifth house has a grow op inside,” BC Hardcore said proudly as his crew put the finishing touches on yet another commercial grow set-up.
“I’m giving away all the secrets of the trade for free. I’ve already made my million, it’s time for other people to go for it too!”