Call him Grow Montana ... because the NFL Hall of Famer is investing HEAVILY in the weed business.
62-year-old Joe Montana is one of the major investors of a company called Caliva -- a major legal marijuana operation out of San Jose, CA.
The company not only grows weed -- it also sells everything from joints to vape pens and even marijuana beverages.
Montana started a venture fund back in 2015 -- and when Caliva was seeking investors for a $75 million round of funding, Montana's company joined in.
Caliva CEO Dennis O'Malley issued a statement saying the company plans on opening retail stores in major cities in 2019.
He added, "What we’re trying to do is be the #1 brand in California ... We believe this is where global brands are made."
As for why Montana decided to invest -- O'Malley says Joe believes the company will "make a serious impact on opioids use or addiction."