Big things are set to happen with the marijuana industry in just eight days, and marijuana stock prices absolutely reflect that fact. In September, a quick screen of the 30 largest and most popular pot stocks by market cap turned up 28 winners and just two marijuana stocks that sank. Those are some pretty good odds.

The reason there's such excitement surrounding marijuana stocks is that Canada is lifting the curtain on a nine-decade ban on recreational pot on Wednesday, Oct. 17. Adults will be free to purchase dried cannabis or cannabis oils in licensed dispensaries or online stores, depending on the province. It's this expectation of a rapid rise in sales and profits that has marijuana stock investors piling into the industry.

A shadow in the shape of a dollar sign atop a pile of cannabis leaves.

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September's top marijuana stocks

Last month, 60% of the aforementioned 30 marijuana stocks rallied by a double-digit percentage. However, five of these pot stocks really stood out, having posted gains of at least 56% to as much as 261% in September. In descending order, here are last's month's best pot stocks.

New Age Beverages Corp.: Up 261.5%

Until recently, New Age Beverages Corp. (NASDAQ:NBEV) wouldn't have been considered a marijuana stock. Then it announced its entrance into the cannabidiol- (CBD-) based beverage market, and everything changed to the tune of a 261.5% monthly gain.

On Oct. 8, 2018, New Age Beverages debuted its new CBD line of beverages at the North American Convenience Store show that was held in Las Vegas. And while CBD beverages are incredibly hot right now, and they could represent an in-demand product as medical marijuana patients in U.S. states look for alternative consumption options, there are a lot of unknowns surrounding this product launch.

Probably the biggest concern is that New Age Beverages' existing product line isn't exactly doing well. Sales of its energy drinks, coconut water, kombucha, and ready-to-drink teas and coffees are expected to collectively decline by 2% in the current quarter and increase by a meager 5% this year. There's simply no guarantee that CBD beverages will be that much of a needle-mover for New Age or that the company's beverages will stand out in what seems to be a rapidly growing and competitive field. 

Long story short, it's a dangerous marijuana stock worth avoiding.

Potted cannabis plants growing under special indoor lighting.

Image source: Getty Images.

Aleafia Health: Up 208.5%

Another under-the-radar business to appear among the best marijuana stocks in September was small-cap medical consultation and growing company Aleafia Health (OTC:ALEAF), which more than tripled after announcing a slew of news.

Perhaps the biggest bump came from Aleafia's announced supply agreement with CannTrust Holdings. Although CannTrust has already been purchasing cannabis from Aleafia Health, this new memorandum of understanding expands that relationship and allows CannTrust to buy up to 15,000 kilograms of weed from the company in 2019. Aleafia noted in its press release that it'll be operating at a fully funded grow capacity of 38,000 kilograms annually by early 2019. 

Aleafia also made waves by partnering with Cronos Group on an insomnia and daytime sleepiness study, as well as catching investors' attention by being added to the Horizons Marijuana Life Sciences ETF last month. As the icing on the cake, it recently applied for listing on the Nasdaq following its incredible ascent.  Of course, the big question will be whether Aleafia can produce enough in the profit department to justify its recent rally, and that remains to be seen.

A jubilant stock trader pumping his fist as he looks at rising stock charts on his computer monitor.

Image source: Getty Images.

Tilray: Up 120.3%

It's probably no surprise that cannabis grower Tilray (NASDAQ:TLRY) makes the list after delivering what might be the wildest ride investors have seen since the dot-com bubble. Despite its volatility, Tilray still finished the month higher by just over 120%.

Why such a huge gain? Part of the answer lies with the company's low float (i.e., the number of currently tradable shares of stock) and the inability of investors to bet against Tilray. The company's stock options are incredibly pricey, and shorting Tilray has been virtually impossible with triple-digit percentage annual borrowing fees from brokerage firms. This has allowed optimists and short-term traders to push this stock significantly higher.

Tilray has also been off to the races on the expectation that it'll find a partner in the pharmaceutical, beverage, or tobacco space. Despite its volatility, Tilray does have established medical marijuana brands, the ability to be a top-tier producer, and international aspirations. Still, its current valuation is a massive stretch and all the more reason for investors to keep their distance.

A potted cannabis plant next to a bottle of wine.

Image source: Getty Images.

HEXO Corp.: Up 60.4%

Formerly known as Hydropothecary, HEXO Corp. (NYSE:HEXO) has been unstoppable since announcing a joint venture with Molson Coors Brewing Co. at the beginning of August. Last month, aside from the ongoing craze surrounding cannabidiol-infused beverages, HEXO rallied following multiple press releases.

For example, HEXO announced the acquisition of an interest in a 2-million-square-foot facility in Belleville, Ontario. It's the company's first venture outside of Quebec, which points to its desire to become a national (and international) weed player. Even more so, this facility will provide for the manufacture of alternative cannabis products, such as vapes, edibles, and nonalcoholic infused beverages. Although no alternatives (save for oils) will be legal come Oct. 17, these high-margin products are expected to become legal sometime next year. 

HEXO also announced that it would be working with Metro Supply Chain Group in Quebec to run a 58,000-square-foot facility that consists of a warehouse and distribution center for adult-use web orders. In other words, HEXO has entrenched itself in Quebec and is quietly becoming a diverse and important cannabis company. 

A tipped-over jar of dried cannabis with a scooper holding a cannabis bud next to it.

Image source: Getty Images.

Green Thumb Industries: Up 56.5%

Last but not least, weed grower and retail-store operator Green Thumb Industries (OTC:GTBIF) had itself a pretty memorable month after reporting its second-quarter operating results in late August.

During the second quarter, the company's sales grew by 291% to $13.6 million, including 25% sales growth from the sequential quarter. More specifically, Green Thumb wound up opening five RISE retail stores during the second quarter, bringing its total number of locations to 13, although it has licenses to open as many as 56 stores in eight key U.S. markets. With the U.S. marijuana industry having a considerably larger peak sales potential than Canada (if legal), there's a lot of excitement surrounding Green Thumb's rapidly expanding branded retail operations. 

Green Thumb has also benefited from recently going public in mid-June. Similar to Tilray, the company is still a few months from hitting the end of its lock-up period, which means its low float has played a role in pushing its share price higher.

For now, investors are probably best off waiting on the sidelines until the company demonstrates its ability to be profitable on a recurring basis.

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.