Making the switch to hemp—what should you consider?

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Now that it is legal to grow hemp in the U.S., greenhouse vegetable and ornamental plant growers are considering whether it makes sense to switch crops.

The Agriculture Improvement Act of 2018, commonly referred to as the 2018 Farm Bill, has legalized the production of hemp. The Agricultural Marketing Service (AMS) is the lead USDA agency to administer the new USDA Hemp Production Program. AMS, which is developing regulations to implement the 2018 Farm Bill provisions announced in the June 24, 2019, Federal Register that it expects to release a final rule in August

Growers in states that have already legalized hemp have been growing the crop according to their state’s regulations. Industry consultant John Dol at CannabiDol has been contacted by both greenhouse vegetable and greenhouse ornamental plant growers about switching to both hemp and cannabis.

“There are people who have been in the vegetable or ornamental plant industry who have made the switch,” Dol said. “There are also people who have been growing cannabis for some time and are looking to expand to a larger production facility.

“One of the challenges is not everyone has the ability/skill set from a managerial point of view. People in the greenhouse industry who have been exposed to managing people, crop scheduling and facility management have found it easier to make the transition to large scale cannabis production. However, specific cannabis plant knowledge will be stronger with the traditional industry players. I think a combination of both these factors in a management team will set a growing operation up for success.”

Differences in production scheduling

Dol said comparing ornamental plant and vegetable production operations, the ornamental growers have an edge in regards to planning because many vine crop vegetable growers only plant once a year.

“Greenhouse tomato growers plant their crops and then they basically maintain them,” he said. “Many greenhouse tomato growers in the Northeast are going to produce a mono crop which means planting in December or early January and then maintaining the same crop until November. Once the crops are finished, the old plants are removed, the greenhouses are cleaned and new crops are planted.

“Many greenhouse ornamental growers produce hundreds of different crops throughout the year. Similarly with cannabis there may be six cycles per year and there is a lot more planning involved with it. In terms of production scheduling, the transition to cannabis should be easier from the ornamentals side.”

Industry consultant John Dol said greenhouse operators who have been exposed to managing people, crop scheduling and facility management should find it easier to transition to large scale cannabis production.

Dol said depending on the cannabis strains being produced, there could be crop cycles every eight to nine weeks. Longer cycle times are available but will diminish overall yield.

“Most greenhouse growers, both vegetables and ornamentals, buy their starter plants from propagators,” he said. “In most cases, cannabis growers have to grow mother plants, cut clones and grow vegetative plants before flowering starts. These are all planning cycles that have to coincide with the flower room schedule. Cannabis production involves multiple grow rooms which makes the planning much more intense.”

Differences in labor intensity

When it comes to the differences in labor tasks involved with growing these crops, Dol said producing cannabis is between vegetable and ornamental crops.

“The work that has to be done with cannabis is less than what has to be done with a greenhouse tomato crop,” he said. “Producing a tomato mono crop for 10 months, the weekly labor tasks include pruning, lowering, deleafing and clipping every plant. That is just the maintenance labor that has to be done on the plants. There is also harvesting and packing.

“These tomato production activities happen from winter to fall five days a week. During the summer and early fall harvesting happens six days a week. A 24-acre greenhouse may have 300,000 plants in it. That is a lot of labor hours needed to produce a tomato crop.”

John Dol said the labor tasks that have to be done with cannabis are less than what has to be done with greenhouse tomato crops.
Photo courtesy of Colorado Hemp Project

Dol said with cannabis crops there is less labor involved because there is less manipulation of the plants.

“There is a lot less labor involved with cannabis,” he said. “With cannabis once the plants begin to flower there may be three deleafings, harvesting and packaging. Depending on the production strategy, bigger cannabis plants take more labor and growers may want to do lower planting densities which involves having to bend the plants more. I prefer to have higher density plantings.”

Dol said greenhouse ornamental crops are the least labor intensive of the three crops.

“Unless the ornamental plants have to be pinched, disbudded or treated with PGRs and/or pesticides, the plants are put in the greenhouse, allowed to grow and then come out at the other end when their ready to sell,” he said.

Differences in pest control

Dol said greenhouse vegetable growers looking to produce cannabis have an advantage over ornamental growers when it comes to disease and pest control.

“Greenhouse vegetable growers have the edge because they have been exposed more to integrated pest management using biologicals and cultural methods to remedy these types of issues,” he said. “Since tomatoes are ready-to-eat products, most vegetable growers only spray as a last resort. This is something that also has application in cannabis production.”

Greenhouse vegetable growers making the switch to cannabis should have an edge with pest control because they are accustomed to using more integrated pest management strategies.
Photo courtesy of Houweling’s Tomatoes

Dol said with cannabis the control methods and products are regulated by individual states, which is one of the difficulties especially for companies with multi-state operations.

“Some states are stricter than others,” he said. “Some states may allow the use of natural oils like garlic oil or rosemary oil. Some states are allowing cannabis growers to use what can be applied to food crops. One of the issues is there hasn’t been a lot of product research done on cannabis because it has been an illegal crop for such a long time.

“For agricultural field crops there are many more acres in production so there are more pesticides and fungicides being used than in greenhouses. Greenhouse growers have always had a harder time getting products registered because there is not as much money in it for the companies developing and labeling the products. The cannabis production space currently is much smaller than the greenhouse vegetable or ornamental space. For the chemical companies it is very expensive and time consuming to have a product reregistered or relabeled for use on a specific crop. Now that hemp is legal, I expect more chemical companies will be looking at re-registering their products. If the hemp is used for medical cannabidiol (CBD), then the regulations are going to be stricter than if the hemp is used for fiber to make clothing or some other products that are not ingested.”

Learning the nuances of growing

Dol said he expects most of the greenhouse growers who are looking to start producing hemp are doing it for the production of CBD.

“If a grower wants to be a year-round producer, in most climates some kind of controlled environment is needed,” he said. “A greenhouse would be the best way to do that because the environment can be completely controlled. For growers producing only outdoors they may need to grow on many more acres to produce the same volume as in a greenhouse where production can occur year round. Water resources are used much less in greenhouses. And from a product quality/safety perspective greenhouses offer much more protection.

“Cannabis is a different plant than other crops that greenhouse vegetable and ornamental growers have produced before. All of the same factors, including light, water, nutrients and carbon dioxide that are required with tomato or mum crops, would apply to cannabis. It’s a matter of understanding what the plants need and also understanding from one cannabis strain to another the needs may be different. Most differences are in irrigation management and crop duration. There are nuances that have to be learned for the different cannabis strains.”

For more: John Dol, CannabiDol,

This article is property of Urban Ag News and was written by David Kuack, a freelance technical writer from Fort Worth, TX.

1 thought on “Making the switch to hemp—what should you consider?

  1. Cannabis: Social, medical or industrial purposes all vary WILDLY in terms of genetics, planting, production, harvesting, processing and market distribution.
    Factors that work in one area will not work in others. Outdoor, indoor & greenhouse ops are radically different environments to grow cannabis.
    It is mission critical to have the above factors and the entire supply-chain fully functional in any of the markets before committing major resources or capital to projects. Regulations and restrictions will also impact this sector over the next five years. Any eye towards the FDA, for example, will determine the status of the current “CBD gold rush”.

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