Many marijuana stocks performed miserably in the first half of 2020. There were multiple factors at play behind the generally dismal returns, with the COVID-19 pandemic weighing on shares of quite a few companies in the cannabis industry.

However, there were still some marijuana stocks that delivered strong returns. Here are three winners from the first half of the year that are still great picks to buy now.

Cannabis leaf in a shopping cart on top of a pile of cash

Image source: Getty Images.

1. GrowGeneration

GrowGeneration (NASDAQ:GRWG) ranked as the best marijuana stock in the first half of 2020 with a gain of 67%. Its shares were pulled down during the overall stock market crash that began in February. But GrowGeneration's performance was so impressive that the stock didn't stay down for long.

The company operates a chain of specialty hydroponic and organic garden centers in 10 states as well as an online superstore. GrowGeneration delivered record-high revenue in the first quarter of $33 million, up 152% year over year. It also achieved record adjusted EBITDA of $2.7 million. 

It definitely helped that GrowGeneration's stores were designated as essential businesses. Most of its stores are in states where recreational marijuana is legal with other stores in states that have legalized medical cannabis. The company benefited as a larger number of consumers who were stuck at home with shelter-in-place orders grew their own cannabis at home.

The hydroponics market in the U.S. could top $30 billion by 2025. GrowGeneration should be able to capture a significant chunk of that market as it launches new stores and continues to roll out private-label products.

2. Scotts Miracle-Gro

Scotts Miracle-Gro (NYSE:SMG) stock soared nearly 27% during the first six months of the year. The company profited from two trends.

First, Scotts' Hawthorne subsidiary benefited from the same factors that helped GrowGeneration. Hawthorne is a leading supplier of hydroponics products for the cannabis industry. The unit generated sales of $230 million in its fiscal Q2, which ended on March 28, 2020. That result reflected year-over-year growth of 60%. 

Second, Scotts' core consumer lawn and garden business flourished. Many Americans seem to have developed green thumbs during the COVID-19 lockdowns. Scotts Miracle-Gro reported U.S. consumer segment revenue of $1.1 billion in fiscal Q2, up 11% year over year. In early May, the company posted its best seven-day period for consumer purchases ever.

Scotts Miracle-Gro's Hawthorne subsidiary should have strong growth prospects as marijuana legalization spreads to more states. The company's consumer lawn and garden business is also poised to deliver solid growth with the launches of organic product lines.

3. GW Pharmaceuticals

Shares of GW Pharmaceuticals (NASDAQ:GWPH) jumped 17% in the first half of 2020. The cannabis-focused biotech had nothing but good news.

GW announced impressive Q1 results in May. The company posted revenue of $120.6 million, more than triple its revenue total in the prior-year period. Those sales were mainly generated by CBD drug Epidiolex in treating Dravet syndrome and Lennox-Gastaut syndrome, two rare forms of epilepsy.

Epidiolex seems likely to keep its momentum going as European sales of the drug rise. U.S. sales could also be boosted thanks to the U.S. Drug Enforcement Administration (DEA) removing Epidiolex from the list of drugs subject to the Controlled Substances Act. This descheduling means that prescriptions for Epidiolex will be valid for a year and can be easily transferred from one pharmacy to another. Physicians will also no longer have to comply with state prescription drug monitoring programs with prescriptions of Epidiolex.

GW Pharmaceuticals could have another major catalyst on the way. The company hopes to win FDA approval this month for Epidiolex in treating tuberous sclerosis complex (TSX), a genetic disease that causes benign tumors to grow on organs.