Marijuana Business Magazine | May-June 2019 136 Best Practices In Cultivation | Bart Schaneman All three growers agree on 18 hours of light per day during the vegetative stage and 12 hours of light and 12 hours of darkness during the flowering stage. “We stagger about half of our facility so that only half of our lights are on at any given time,” Lustig said. “It lowers the energy demand on the system, and it saves us some money.” Monroe measures his light levels with a laser temperature gun. He shoots the laser at the leaf surface of a plant, hoping for 76-78 degrees. If you have too much light, the temperature will read warmer, he said. “If it’s 82 degrees, what that’s telling me is that the plants aren’t actually using the energy I’m giving them,” he said. Drooping leaves are another sign a plant has received too much light. This signals the plant is trying to minimize the surface area of its leaves to decrease the amount of light it’s taking in. That could also cause plants to flower less prolifically, Monroe said. Varying the Light Spectrum Cultivators commonly use cooler lights such as metal halides in early, vegetative growing stages and switch to hotter, red-spectrum HPS lights during flowering. Kline said he starts his plants under metal halide lights because the blue spectrum increases vegetative growth and helps to build plant structure. Then, he moves them under HPS lights, the red spectrum, to spur flower growth. “The light spectrum can dictate the height and shape of your plant,” he said. LED R&D The traditional method of hanging light-emitting diode (LED) or high-pressure sodium (HPS) lights above your canopy can yield perfectly serviceable results for your grow room. But experimenting with other arrangements and techniques may help you get a leg up on the competition. At Seed & Smith, a vertically integrated cannabis company in Denver, founder Brooks Lustig has rooms dedicated to research and development, where he plays around with new setups. For instance, in one room he’s trying out sub-canopy LED lighting. A long LED light bar is mounted in the tray below the canopy and shines up at the plants. “We’re trying to shine light from down low to increase the height of the canopy, so that more productive buds will grow in the previously shaded spots,” Lustig said. In Canfield, Ontario, master grower Gord Kline experiments for High Street, a vertically integrated cannabis company. Kline uses six, 40-foot-long shipping containers that have been retrofitted to try out different spectrums and lighting equipment. For example, he’s been experimenting with water- cooled LED lights to determine if they will be an efficient, cost-effective addition to his facility. He’s also interested in vertical growing, where cultivators stack their benches on two or three levels and the lights are strung from the bottom of trays stacked above. LED lights can be hung much closer to the plant than other lights because they emit less heat. This is a great way to maximize the space in your grow room, Kline noted. “Your plant doesn’t react and get stressed out by the light intensity,” he said. Growers looking to experiment with new techniques should do so with caution, Lustig advised. One consideration: You can fry your plants. Whenever he’s looking to increase or change a variable, Lustig keeps a control to determine if he’s gaining better yields or wasting his time. “Make sure to do it in a controlled-type fashion,” he added. “Don’t go zero to 100 right away.” – Bart Schaneman Gord Kline Lighting levels can be tweaked to optimize energy costs and achieve efficiencies. Photo Courtesy of Swift Cannabis As technology evolves, it helps to have a dedicated space to try new lights. Photo Courtesy of High Street Bart Schaneman covers cultivation and extraction for Marijuana Business Magazine. Reach him at [email protected] .