Cost efficiency in marijuana cultivation: Q&A with veteran grower Justin Sheffield

After learning the fundamentals of plant and soil science at Middle Tennessee State University, Justin Sheffield moved to Denver in 2011 to work at Medicine Man Technologies, then a medical marijuana operator.

That was the year before Colorado voters endorsed what would become the first U.S. market to launch adult-use marijuana sales.

And Sheffield, with a comprehensive understanding of commercial horticulture, was intrigued by the innovation happening in the fledgling cannabis industry.

The journey has led him from Colorado to South Carolina and, ultimately, Missouri, which launched its own adult-use market in February 2023.

Today, Sheffield oversees three grow sites as director of cultivation for BeLeaf Medical Co., a licensed marijuana operator located outside St. Louis, and its flower brand, Sinse Cannabis.

MJBizDaily spoke with Sheffield about lessons he learned growing outdoor hemp by the acre and marijuana by the square foot, such as maximizing efficiencies and safe ways to control pests.

Having grown marijuana indoors and hemp outdoors in multiple states, what are the similarities and differences?

I worked at a couple of places around Denver and Boulder over the years, and then I jumped to Durango, Colorado, where we started producing hemp and feminized hempseed in a greenhouse.

That was so much fun because it was the opportunity to take everything I’d learned and built on a square-footage scale and expand it to an acreage scale.

It was essentially the same, just times 1,000.

After Zion Farms (near Durango), my wife and I moved to South Carolina to do the hemp operation for Arrowhead Seed Co., going from the high desert of Colorado to the low country of South Carolina.

And again, it’s the same crop, but instead of cold and dry, it’s as hot and as humid as it can be – and cannabis loves that.

How did growing acres of hemp compare to growing marijuana indoors?

Efficiencies. We experience this in marijuana, too, but it was always:

• How can we do this more efficiently?
• How can we bring these COGS (cost of goods sold) down?
• How can we operate leaner?

And now, as the THC market matures, the ones that survive are those that operate efficiently.

One thing I like to say is: Anybody can grow a great pound of marijuana, but it’s very hard to grow a great pound of marijuana for $300 and then do that six times per year.

That’s where the skill comes in with commercial growing and crop scheduling.

What other lessons from hemp did you bring when you switched back to high-THC cannabis?

One skill that you were forced to master or not make it would be effective and compliant pest management – especially being outdoors in South Carolina.

The plants grew with a vigor that I’ve never seen, but (there were) also far more pests and pathogens than I’ve ever seen.

At BeLeaf – specifically for the size we are, being an indoor operation – our pest management is on point.

We understand the different species of pests and pathogens, and we have a pretty robust preventative program in place.

The whole goal with the IPM (Integrated Pest Management) program – like with the operation in general – is trying to be proactive and not reactive.

(Section) 25(b) means you’re exempt from (Environmental Protection Agency) registration as a pesticide; so generally, a 25(b) product would be something like a soybean oil or a citric acid or generally very safe compounds.

Using these and using them at the right time, you definitely keep the pest population low.

But there’s a difference between an efficient spray schedule and overkill.

We pull off sprays completely (in the flowering stage) and then use beneficial biological-control agents, or beneficial insects: It’s mainly beneficial mites that look for any pathogenic mite that might make its way in.

And we also use nematodes.

We love nematodes and have seen just excellent, excellent efficacy using those for fungus gnats, for thrips, for anything that lives or pupates in the soil.

The nematodes will just wipe them out. We use nature to fight nature.

What do you think the experience of getting an agriculture degree brings to your grow operations?

Being able to collect, analyze and better the operation based off of data.

We want to know so much more: What did they eat? What did they yield? How do little environmental changes impact the final product?

Do you use any technology to help you collect and analyze that data?

We use Argus Controls for our building-control system, and that controls heating, cooling, humidity and lights.

But what it also does is it graphs everything, and that’s extremely helpful for us when we have a really great run or a really poor run, to sit down and look at everything and say: What changed on this run that didn’t happen on the one behind it?

And often we’re able to say, “Look, our nighttime (temperatures) dip down into the 60s, and this last one they didn’t … and if we can keep them at 75, we can see 10% more yield.”

Comparing those historical graphs that Argus has given us has been great.

This interview has been edited for length and clarity.

Kate Lavin can be reached at kate.lavin@mjbizdaily.com.