The basics of growing cannabis

There are few pesticides available to help protect the crop

Reading Time: 3 minutes

There’s still a lot to learn about cannabis production in Ontario, with limited pesticide options and evolving technology.

Bill MacDonald, professor and co-ordinator with Commercial Cannabis Production at Niagara College recently introduced aspects of cannabis production to attendees of the SouthWest Agricultural Conference held in Ridgetown.

Why it matters: Cannabis production presents an opportunity for growers across Ontario, but expertise and understanding of its production are limited because it has been legal to use recreationally only since October, 2018.

Only female plants are grown within cannabis production. Bracts are important to cannabis production and are found on the buds of female plants.

Within the bracts are trichomes, which produce cannabinoids such as cannabidiol (CBD) and tetrahydrocannabinol (THC), both of which provide the feeling of relaxation and are thought to have anti-inflammatory properties.

The term cannabis covers both hemp and marijuana. Although both are the same species, cannabis sativa, marijuana has been bred for its THC content, making it more common for cannabis production.

Bill MacDonald.
photo: Jennifer Glenney

“Hemp is classified as having 0.3 per cent or less THC,” says MacDonald at the Jan. 7-8 conference.

It’s important in production of cannabis, that the plants don’t go to seed.

“We are producing trichomes, we don’t want the energy going to seeds. It’s weight that is unusable.”

Much like poinsettias, cannabis is a short day plant, requiring 12 hours or less to flower.

As with other plants, disease and insects pose problems. Unfortunately, cannabis production has limited pesticide options.

Currently, there are 25 pesticides registered for use on cannabis, including Milstop, Opal Insecticidal Soap, Rootshield and Botanigard.

The pesticides can only be used for indoor and greenhouse production. There are no pesticides registered for outdoor production.

Related Articles

“(Farmers) are extraordinarily limited for cannabis — you are pretty much growing organic and using environmental controls,” MacDonald said.

In 2017, following three recalls of cannabis for medicinal purposes due to unauthorized pesticide use, Health Canada announced it would begin a series of unannounced inspections, along with mandatory testing for the presence of pesticide active ingredients in all products.

Cannabis can be grown indoors, outside or in a greenhouse, all three of which provide different opportunities.

When grown indoors, everything about the production is artificial, yet production is consistent.

“Year-round production provides year-round employment,” MacDonald says.

The air within the production system is filtered, allowing for more pest and disease control. Although once disease does enter the system, it spreads quickly.

Indoor production means high construction costs. Large amounts of energy are consumed and can be difficult to scale.

Growing within a greenhouse offers year-round production and employment as well.

It provides natural light, but supplemental light is used extensively.

“It’s a high-value crop so it’s worth the supplemental lighting.”

Within a greenhouse, growers have to compensate more for the environmental swings by adding heat in the winter and cooling in summer.

It’s ideal for all vents to be screened to try and contain pests and diseases.

Last year was the first year in which Health Canada allowed outdoor cannabis production.

With outdoor production, growers are at the mercy of the weather.

“You have to hope for a (good) fall for harvesting. But you can get very good yields,” MacDonald said.

All fields have to be licensed by Health Canada. As well, proper security systems must be installed, such as cameras, motion sensors, fencing and barbed wire.

This type of production has lower energy costs.

Pesticide and pollen drift can be concerns, but in 2019, MacDonald said there didn’t seem to be as much of a problem as farmers predicted.

MacDonald says that the current industry is over capitalized.

“Everybody wanted to get in, everyone wanted to make money and everyone thought they were millionaires overnight.”

Now, investors are wanting to see their return on investment.

MacDonald says the future of cannabis production is all about returning to the basics.

Those include agronomic understanding, breeding for cultivars that are resistant to powdery mildew and learning how to produce a high quality crop.

MacDonald also says that micro-cultivars will be a production opportunity.

He says facilities of 2,200 sq. feet or less, though small, can still provide a profit and there’s opportunity for on-farm sales.

“It’s in the federal legislation. It’s still making its way through the province. As far as we know you will be able to have farmgate sales.”

“It’s not rocket science. Produce a good crop, control your costs and control pests and diseases.”

About the author


Jennifer Glenney

Jennifer lives on a farm in Cayuga, Ontario and has a lot of experience in the many aspects of agriculture.



Stories from our other publications