There's no denying that marijuana stock investors were thrilled to see 2019 come to a close. After beginning with epic first-quarter gains, which saw more than a dozen pot stocks rise by at least 70%, cannabis stocks have since been stuck in a nine-month freefall.

What's to blame? Look no further than supply issues in Canada that have kept product from reaching consumers, and high tax rates in select U.S. states (ahem, California), which have made it extremely difficult for legal cannabis to compete with black market producers. Throughout North America, illicit producers reigned in 2019.

But a new year brings new opportunities for the pot industry. The official launch of derivative marijuana products in Canada, and the expected legalization of weed in a handful of new U.S. states, should ignite top-line growth. Using revenue as the primary growth metric, the following seven marijuana stocks are expected to be the fastest growing in 2020.

A handful of cannabis buds lying atop a messy pile of cash.

Image source: Getty Images.

1. Auxly Cannabis Group: Estimated sales growth of 1,109%

Among the dozens upon dozens of publicly traded pot stocks, Auxly Cannabis Group (OTC:CBWTF) takes the crown as the fastest-growing cannabis company. Of course, this comes with a bit of an asterisk given that Auxly has purposefully held back dried cannabis production with the intent to use it in derivative pot products, such as edibles. As some of you may know, the launch of derivatives was delayed by Health Canada until mid-December, meaning the bulk of Auxly's revenue ramp-up has been pushed into 2020.

Furthermore, Auxly will see a number of its royalty partners make their first deliveries this year, and should see a key joint venture cultivation farm begin to pay dividends. Though profitability may still be more a year out, the company's per-share loss is expected to shrink in 2020.

2. Flowr Corp: Up 731%

Revenue growth should also pick up notably for British Columbia-focused specialty grower Flowr (OTC:FLWPF), with sales advancing from a little less than $10 million in 2019 to roughly $80 million this year. This increase has a lot to do with Flowr's Kelowna campus ramping up production, and Flowr also holding back some of its dried flower production to focus on high-margin derivatives.

What'll be particularly interesting to watch with Flowr is that it's predominantly growing premium and ultra-premium quality weed. Upper echelon-quality cannabis shouldn't face the same pricing pressures as average and discount-quality marijuana, which I anticipate will lead to rapid sales and margin expansion.

An up-close view of a flowering cannabis plant in a commercial indoor farm.

Image source: Getty Images.

3. The Green Organic Dutchman: Up 545%

Projected sales growth of 545% for The Green Organic Dutchman (OTC:TGOD.F) probably sounds impressive, but it comes with a couple of caveats. For one, the company has been late to the game in developing its cultivation farms and getting product to market. That means it's building off of very little in fiscal 2019 sales.

The other consideration here is that TGOD, as the company is also known, was the first major Canadian grower to announce production cuts this past October. Having previously touted its peak annual production capacity as 219,000 kilos, TGOD is now forecasting 2020 production of only 20,000 kilos to 22,000 kilos. Just the Ancaster facility, and a mere four grow rooms at its flagship Valleyfield property, will be used for production this year. This will certainly limit TGOD's sales potential, but should help push the company toward its goal of generating positive operating cash flow.

4. Harvest Health & Recreation: Up 459%

According to Wall Street's sales estimates, the fastest-growing U.S. pot stock in 2020 should be multistate operator (MSO) Harvest Health & Recreation (OTC:HRVSF). Wall Street expects sales to skyrocket from around $118 million to $661 million.

Though Harvest Health isn't a very well-known MSO, relative to some of its peers, it's poised to be a major player, assuming all of its acquisitions come to fruition. It's pretty much in a dead heat with Curaleaf Holdings for most retail store licenses on a pro forma basis, and has approximately 210 licenses, inclusive of cultivation farms and processing facilities. As Harvest Health opens up a number of retail locations this year, and benefits from the ongoing state-level legalization effort, especially in Arizona, it should deliver substantial year-over-year sales growth.

A green highway sign that reads, Welcome to California, with a white cannabis leaf on the right-hand side.

Image source: Getty Images.

5. Cresco Labs: Up 312%

Speaking of fast-growing U.S. MSOs, Cresco Labs (OTC:CRLBF) should see its full-year sales rocket from $132 million to about $545 million, year-over-year. Like Harvest Health, Cresco Labs is going to benefit from opening a number of new retail locations, including in Illinois, which commenced adult-use cannabis sales on Jan. 1.

However, Cresco should also see a sales uptick if and when its all-stock acquisition of Origin House closes. Origin House is one of only a small handful of companies to hold a cannabis distribution license in California, the largest weed market in the world by sales. If the deal closes, Cresco Labs would not only be privy to Origin House's steady stream of revenue, but would also gain access to over 500 dispensaries in the Golden State. Being able to place its products in these dispensaries is what'll help Cresco's sales soar.

6. Cronos Group: Up 214%

Arguably the most popular company with investors on this entire list of fast-growing pot stocks is Cronos Group (NASDAQ:CRON), which should see sales more than triple to approximately $87 million in 2020.

Similar to other Canadian growers, Cronos' sales growth is projected to be so robust because it's building off of a year of modest sales. Though the company has been saving some of its dried cannabis for derivatives, Cronos has been especially slow to expand production compared to a number of its peers. With substantially less in the way output relative to similarly sized growers, Cronos' sales haven't been much to write home about. The launch of derivatives in Canada, and the expected completion of a joint-venture grow farm this year, should help boost Cronos Group's top line.

A vial of cannabinoid-rich liquid lying atop cannabis flowers.

Image source: Getty Images.

7. The Valens Company: Up 213%

Last, but certainly not least, extraction-services provider Valens Company (OTC: VLNCF) will see its sales catapult by an estimated 213% to $131 million in the current year.

Valens is benefiting from its central role in the derivatives launch. You see, Valens processes hemp and cannabis biomass, thereby supplying resins, distillates, concentrates, and targeted cannabinoids to its clients. These high-margin extracts are what go into edibles, topicals, and infused beverages. Considering that Valens has signed a number of two-year extraction agreements with brand-name Canadian growers, and is working toward an eventual processing capacity of 1 million kilos per year, it's not the least bit surprising that it makes a list of the industry's fastest-growing companies.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.