August was a dismal month for most marijuana stocks. More than half a dozen pot stocks with market caps greater than $200 million plunged 20% or more during the last month. Several others fell by double-digit percentages.

But there were a few exceptions to the August carnage. Three marijuana stocks performed really well last month: 22nd Century Group (NYSEMKT:XXII), Aphria (NYSE:APHA), and The Green Organic Dutchman (OTC:TGODF). Here's what drove these pot stocks higher and whether or not they're good picks to buy now.

The summer is almost over, and we can officially call it a bad one for marijuana stocks. Since June, Horizons Medical Marijuana Life Sciences ETF, which tracks the entire sector, has shed 23% of its value, with no end in sight.

Driven by rising losses and increasing regulatory drama, weed stocks are beginning to lose their lustre and fall out of favour with investors. Although revenue growth in the industry remains sky high, profits for the most part are nowhere in sight, and many are beginning to wonder if they’ll ever become a reality.

If you still own weed stocks and aren’t sure whether to hold or sell, the following are three of the sector’s worst performers that it would be wise to get out of quickly.

Ontario government defends updated list, saying vetting will include police checks.

As cannabis sales in Alberta top the country, a Calgary professor says online sales could pose new challenges for countering fraudulent IDs and securing consumer data.

Currently, only Alberta Gaming, Liquor and Cannabis is permitted to sell cannabis online in Alberta.

But as the private sector plans to enter the market, verifying a customer’s identity online becomes a lot more difficult, said Thomas Keenan, a professor focused on data and cyber security in the University of Calgary’s School of Architecture, Planning and Landscape.

Following a C$250 million boost, Canadian firm Sundial Growers has splashed out one of the U.K’s largest horticultural operations to supply the booming European CBD market.

August wasn't a great month for most marijuana stocks. For that matter, neither was May, June, or July. Ups and downs come with the territory with investing in marijuana stocks, though.

Over the long run, the marijuana industry is expected to show a lot of promise. Various Wall Street forecasts suggest that worldwide legal weed sales can grow from $10.9 billion in 2018 to anywhere between $50 billion and $200 billion in about a decade's time. That's growth that Wall Street and investors would be foolish (with a small "f") to overlook.

While cannabis edibles are a hot topic in Canada these days, there are supposed to be strict regulations in place to dissuade youngsters from trying them. But those rules don’t necessarily apply south of the border.

Having legalized cannabis for recreational purposes last year, the final piece of the puzzle is the delicate area of THC edibles, gummies in particular. While such edibles will officially become legal in Canada on October 17th, they cannot be “appealing to young persons.” The finer details of the regulations are yet to be announced by Health Canada.

While recreational cannabis has been legal in Canada for over six months, black market weed sales are still significant in the country.

In the first half of 2019, Statistics Canada reported in August that 42 percent of cannabis consumers bought the drug from illegal sources, up from 38 percent in the first three months of 2019.

That is a significant number of cannabis users turning to the black market, despite legal purchasing options available.