The marijuana industry has had an absolutely game-changing year in 2018. Canada became the first industrialized country in the world to green-light recreational marijuana, and a handful of U.S. states legalized cannabis in some capacity. In other words, the pot industry gained validity like never before.

According to investment bank Cowen & Co., the legal weed market could be worth as much as $75 billion by 2030. That would suggest there's plenty of opportunity for investors to make money over the long run from both direct and ancillary players. Although the legal cannabis market is still exceptionally young and unproven, here -- in no particular order -- are 12 pot-growing stocks you should be watching in 2019.

All buzz surrounds these dozen cannabis growers in the new year

1. Canopy Growth (NYSE:CGC): It's the largest marijuana stock by market cap. The company currently has 4.3 million square feet of licensed production capacity, and anticipates having all 5.6 million square feet licensed by the end of 2019. Though Canopy hasn't offered specific production guidance, about 500,000 kilograms at peak capacity is likely. Canopy Growth has what's arguably the most recognizable cannabis brand in all of Canada (Tweed), and has a top-tier partner in Constellation Brands, which owns 37% of Canopy. Expect Canopy Growth to be active on the acquisition front in 2019 with more than $4 billion in cash and cash equivalents on its balance sheet.

2. Aurora Cannabis (NYSE:ACB): In terms of peak production potential, no company tops Aurora Cannabis. Following four major acquisition closings and/or announcements in 2018, Aurora could be on pace for 700,000 kilograms of peak annual output within two or three years. Aurora does have a penchant for diluting investors with bought-deal offerings, but its production superiority may lead to desirable competitive advantages. Expect 2019 to be the year that Aurora finds a beverage, tobacco, or pharmaceutical partner, and don't be surprised if the company's acquisition binge continues.

3. Aphria (NYSE:APHA): It faced allegations in December that its management team knowingly acquired "worthless" assets in Latin America for approximately 300 million Canadian dollars ($222 million). Aphria has since refuted those claims many times over, leaving an interesting story to play out in the coming months. What we do know is that if management meets its production guidance, Aphria will slot in as the third-largest grower by annual yield at 255,000 kilograms. Roughly 10% of this output will be devoted to high-margin cannabis concentrates, with Aphria's extraction center likely being completed in 2019.

4. The Green Organic Dutchman (NASDAQOTH:TGODF): TGOD, as the company is also known, is an interesting case. Following three capacity-expansion announcements in June, it pushed its peak production potential to 195,000 kilograms. Depending on its peers, this could slot TGOD as Canada's fourth- or fifth-largest annual grower. What's interesting is that it won't even register its first sale until the first half of 2019, making its entrance into the cannabis-growing space particularly late. Roughly 40,000 kilograms of TGOD's production will be devoted to edibles and infused beverages, which could make it an intriguing partner for brand-name beverage and snack companies next year.

5. Tilray (NASDAQ:TLRY): It is the only Canadian-based pot stock to go the initial public offering route via a major U.S. exchange. It offered a blistering return pace through mid-September, shooting from its $17 list price in mid-July to $300 on an intraday basis in September before crashing back to earth. Tilray has close to 3 million square feet in growing capacity that it could develop, which makes it a wild card in terms of peak production. The company also snagged a global distribution deal for a noncombustible, nonsmokable medical cannabis product with Sandoz (a subsidiary of Novartis), and a beverage joint venture with Anheuser-Busch InBev in Canada, within the past two weeks.

6. CannTrust Holdings (NASDAQOTH:CNTTF): As of the end of 2018, CannTrust's massive Niagara Greenhouse project should be complete. When combined with its Vaughan facility, we're talking about roughly 1.1 million square feet of hydroponic grow space (i.e., growing plants in a nutrient-rich water solvent, as opposed to soil), complete with moving containerized benches at Niagara, creating a perpetual harvesting system that should lead to consistent output. With management expecting in excess of 100,000 kilograms at peak annual production, this low-cost producer is worth keeping a close eye on.

7. OrganiGram Holdings (NASDAQOTH:OGRMF): Often overlooked because of its location, OrganiGram is the largest Atlantic-based grower by output. The company anticipates completing the final of three stages of its phase 4 expansion at the Moncton, New Brunswick, facility by October 2019. When fully operational, this three-tiered growing system spanning 490,000 square feet should be capable of 113,000 kilograms of low-cost annual output. This would place OrganiGram within the top 10 of Canada's largest growers, and potentially give the company a chance to boast some of the lowest growing costs throughout the industry.

8. HEXO (NASDAQOTH:HYYDF): This Quebec-based company is another grower that doesn't get a lot of attention now, but it could start turning heads in 2019. At the beginning of August, HEXO signed a joint venture with Molson Coors Brewing to develop cannabis-infused beverages, which aren't even legal yet in Canada. This partnership could put HEXO on the map...assuming the company's peak production estimate of 108,000 kilograms doesn't. With a long-term supply deal for 200,000 aggregate kilograms over five years with Quebec under its belt, HEXO could be among the steadier performers next year.

9. Cronos Group (NASDAQ:CRON): Like Canopy Growth, Cronos Group will have a boatload of cash. That's because Altria recently agreed to take a 45% stake in the company, equating to $1.8 billion. Cronos plans to use this cash to further its branding and marketing, as well as to ramp up its expansion into foreign markets. Logically, Altria and Cronos would also be expected to collaborate on cannabis-based products, which may include vapes, assuming Canada's Parliament legalizes these alternative consumption options in 2019. Cronos will also be looking to complete its joint venture project, Cronos GrowCo, which is capable of producing 70,000 kilograms at peak capacity.

10. Emerald Health Therapeutics (NASDAQOTH:EMHTF): Shareholders hope to see the fruits of Emerald Health Therapeutics' projects begin to pay off in 2019. Having partnered with Village Farms International, the two are working on Pure Sunfarms -- a 1.1-million-square-foot retrofit of existing vegetable-growing facilities to grow cannabis. Emerald Health and Village Farms aim to produce at least 75,000 kilograms. When adding in Emerald Health's purchase of Agro Biotech and the development of its Metro Vancouver facility, it has a shot at surpassing 100,000 kilograms in peak production.

11. The Supreme Cannabis Company (NASDAQOTH:SPRWF): Absolutely the sprite of the bunch, Supreme Cannabis is worth a look because of the premium-quality pot coming out of its 7ACRES facility. Despite only 342,000 square feet of growing space, Supreme Cannabis has visions of generating 50,000 kilograms of weed per year. It also happens to be one of the cheapest pot stocks on the basis of its forward price-to-earnings ratio. It'll be interesting to see if this relative small-fry can find a brand-name partner in 2019.

12. Auxly Cannabis Group (NASDAQOTH:CBWTF): Last, but certainly not least, is Auxly Cannabis Group, a company known best for its royalty interests in grow farms. Recently, though, Auxly has begun acquiring small and midsized grow facilities, giving it more direct skin in the game. Since Auxly's royalty interests have low but fixed costs, entering the grow side of the industry should allow the company to further push down its expenses, more than just the royalty side of the business would have allowed. With production and partner deliveries expected to really ramp up in 2019, Auxly is eventually angling for 170,000 kilograms in peak annual sales.

In sum, there's a lot of green to keep track of in this high-growth industry.