The how-to of hemp

The first test crops of industrial hemp (Cannabis sativa) have been growing since early summer at the John C. Pair Horticulture Center in Haysville near Wichita, the Olathe Horticulture Research and Extension Center in the Kansas City metro area, and the Northwest Research-Extension Center in Colby.

K-State researchers are seeking answers to many questions, including whether to grow hemp for grain, fiber or CBD oil.

The majority of the revenue stream in this expanding market comes from CBD production, says Jason Griffin, director of the John C. Pair Horticulture Center. But there are emerging markets for hemp paper products to flooring materials and even hempcrete – concrete reinforced with hemp fiber to strengthen it, he adds.

K-State Research and Extension is testing several different production techniques (including field grown and containerized plants in high tunnels), fertilizer treatments and looking for pests and diseases. The outdoor crops were grown from seed acquired from the USDA’s multi-state industrial hemp project and the indoor crops were clonally propagated from cuttings.

“Think of the fiber and grain hemp varieties as an agronomy crop,” Griffin says. “It’s grown similar to corn or wheat production and in Kansas seeding occurs about the same time as corn. Conventional nursery growers could use fiber or grain hemp like a cover crop. For CBD hemp, it’s typically grown under cover like a mum or a spirea.”

The Pair Center is testing 17 different varieties, while the Olathe center planted one variety to observe how multiple environments affect growth.

Researchers have observed that containerized hemp produced in the high tunnels grows quickly.

“Rooted cuttings were potted into a 1-gallon container and plants outgrew those pots in two to three weeks. Then we shifted those plants up to a 7-gallon container. We’re using the standard soilless nursery substrates and standard controlled-release fertilizer.”

The CBD hemp varieties can be grown outside, but only if there’s no wild hemp nearby that would pollinate the valuable crop.

“Pollen will carry up to 3 miles. The oil is produced in the female flower bud and if it gets pollinated, the plant will stop making buds and start producing seed. We’re experimenting with insect netting on the high tunnels to see if that keeps the plants from getting pollinated,” he explains.

The researchers have recognized some familiar faces when it comes to insect pests, such as aphids, spider mites and thrips, Griffin says.

“In the field plots we’ve also seen corn borers. And researchers in Kentucky identified hemp leaf spot, which can be pretty devastating,” he adds.

Currently there are no pesticides labeled for cannabis.

In the CBD oil crops, researchers have found that some varieties need pinching and some are resistant to powdering mildew.

For more: Jason Griffin, jgriffin@ksu.edu

Jason Hackett of Kansas State University contributed to this article.