Preventing outbreaks of pests and diseases in growing facilities is a top priority for cannabis cultivators, which is why Harbor Farmz utilizes tissue culture to create the healthiest mother stock plants possible for its nearly 11,000-square-foot canopy.
“The really good thing about having tissue culture in a production facility is that tissue culture is free of any kind of diseases like powdery mildew, botrytis or any kind of viruses, which let’s face it, can make or break a facility,” says Deb Sweeney, tissue culture lab director at Harbor Farmz. “It also reinvigorates the cultivars. When you’ve been cloning plants, you’re cutting them over and over. There’s an open wound there and what’s the plant going to try to do? It’s going to try to heal itself. When there’s an open wound, any kind of systemic disease can go in there.”
Tissue culture plants are incredibly tender and delicate, so Harbor Farmz must provide the best growing environment possible to ensure these plants get a strong start before advancing through its growth stages, Sweeney says. And lighting is one of the most important factors in achieving success throughout the growth cycle.
Here, Sweeney and Allister Malcolm, who also works in the tissue culture lab, share four best practices for lighting in tissue culture.
1. Start Slow and Low
Working in tissue culture is akin to trialing all of the time, as each cultivar has different lighting preferences, Sweeney says.
But no matter the plant, starting at a low lighting intensity is key to prevent the young and fragile plants from burning. Harbor Farmz chose the RAZR LED Series from Fluence by OSRAM, which allows the company to grow tissue culture vertically in a modular system and to keep lights a safe 4 to 8 inches from plants.
“What is great with the RAZR II is its lower intensity lighting, so we’re able to gradually increase it and listen to what the plants want,” Sweeney says. “[LEDs] don’t emit as much heat, and we also save energy.”
2. Consider Space-Saving Tiers
The plant nursery in the tissue culture lab take up less than 20 by 20 feet of space, but thanks to vertical growing, that relatively tiny corner of Harbor Farmz nearly 36,000-square-foot facility holds the beginnings of nearly 1,500 plants at any given time, Malcolm says.
“It’s almost like a bookshelf,” Sweeney says of the shelving units where tissue culture plants grow. “So, it’s literally a shelving unit about 10 feet high, give or take, and we have between 13 and 14 shelves in each shelving unit. We can grow thousands of vessels of tissue culture plants.” The system is possible thanks to the low heat producing LEDs that allow for stacking and close proximity to plants.
3. Gradually Increase Lighting While Watching Plants Closely
Tissue culture plants spend anywhere from four months to a year prepping for the next growth phase in Harbor Farmz’s lab, with the average being six to nine months, Malcolm says.
“When we’re first starting plants out and initiating them, we start them out with a