Building Strong Roots - Guide to Growing Hemp and Cannabis
Building Strong Roots
(excerpts from the article by Jolene Hansen in HempGrower magazine)
Advances in container technology can help optimize plant root growth from propagation to the field.
Growers new to container production eventually learn that all pots aren’t created equal. It’s a lesson producers of mainstream container-grown horticultural crops have long known—and that progressive container companies continue to prove. Exploring technological advances in growing containers, often backed by decades of horticulture industry research and use, can help growers decide what pots best suit their needs—and their roots.
Looking Beyond Traditional Plastic
Standard plastic nursery containers are a common choice for many container growers. Used throughout the nursery and greenhouse industries, solid, straight-sided plastic pots are easy to source through suppliers nationwide. But experienced growers will tell you: This relatively inexpensive, easy-to-sterilize and re-usable option can sometimes spell trouble. Plants held in solid plastic pots often develop circling roots, which inhibit growth, complicate transplanting and limit yield.
When Matt Spitzer, founding partner of Triangle Hemp in Raleigh, N.C., moved into hemp from the hydroponic produce space, he soon discovered the negative impact solid plastic and girdling roots had on the company’s seedlings and clones—especially if Triangle had to hold starts longer than expected when field farmers faced weather delays.
In looking for solutions, Spitzer turned to the ornamental tree industry. “They were the industry that really had the biggest issue with regard to root girdling,” he shares. As he explored container options being used in the tree industry, he learned that container-grown tree roots respond differently when they hit air instead of solid container walls. Rather than circling the pot’s interior, roots stop outward growth—as though they were pruned—and instead focus on dense, fibrous, lateral growth instead.
This natural air-pruning response has spawned an industry of container companies aiming to capitalize on this reaction and optimize healthy root growth. These “aeration pots,” available in materials from papers to plastics, offer increased air-to-root interfaces that have been proven in traditional horticulture to air-prune roots, release root zone heat, discourage root disease and promote higher yields.
Working with aeration pots has been key to Triangle Hemp’s success and given rise to its rootbound-free guarantee, says Spitzer. “That actually gave us a leg up [in the] second year of production because not many people were really aware of the issue with transplants,” he says. “So, we were able to produce a superior product that was not rootbound. The people who had never planted hemp before didn’t quite know that was so important. But if you had planted the year prior, you knew it was very important.”
At Triangle Farm, Spitzer turned to fabric aeration containers to minimize the risk of root disease and binding roots in the company’s mother plants.
Already familiar with fabric containers and their benefits, he settled on the RootTrapper II line by RootMaker, a container company based in Huntsville, Ala., that has served ornamental tree growers for decades. These soft-sided black fabric pots are laminated with a white coating down to the bottom 2 inches of the pot. Designed to eliminate circling roots and stimulate dense lateral root branching, the air pruning pots allow drainage at the unlaminated base while the pot’s coating protects the root ball against rapid moisture loss.
“We found this RootTrapper II container was really well-made and served a purpose for our mother plants extremely well,” Spitzer says. “It just ensures that we don’t have any binding at the base of our plants. This entire line is really quite geared towards hemp production because of their root pruning capabilities.”
Air Pruning With Plastic Options
At Hemptek, a hemp farm in Oregon’s Willamette Valley, CEO Dennis McGuire approached choosing containers for the farm’s field-destined propagation with an eye on complementing the farm’s organic focus. “It’s a challenge growing starters and everything just using all-organic products,” he shares.
After buying starts from various companies, McGuire says he grew dissatisfied with tight propagation trays that left little leeway for transplant timing—a big problem in the Pacific Northwest, where fleeting weather windows can put plans on hold for weeks. As a result, he opted for plastic trays that feature an updated design to address potential root spiraling and other issues plants grown in traditional plastic pots may develop—specifically, RootMaker plastic air pruning propagation trays, which offer a graduated, multi-cell design that directs roots toward the container’s air holes.
McGuire compares air pruning and the fibrous roots it creates with the way exercise helps grow new blood vessels to transport blood and oxygen through the body more efficiently. “You can use the best soil you want, but if you don’t have the right propagation tray, the plant still won’t have the foundation—the root structure—it needs,” McGuire says.
He adds that using RootMaker’s air pruning trays from seed to field accentuates the benefits of Hemptek’s custom organic soil. The result is a sturdy transplant, free from spiraling roots, with short internodes and compact growth that withstands Pacific Northwest winds in the field, he says.
Investing in Your Roots
For growers exploring container options, Ortega says to keep the plant’s root system foremost in mind. “In cannabis and hemp, a lot of investment goes to lights. A lot of investment goes to humidity and temperature control,” he says. “This is investing in your root system. If a plant has a good root system, it’s going to be able to handle a lot of variables.” ...