In 2010, Jake George saw a market waiting to be served and staked everything on a startup: He and his wife, Lydia, sold most of their assets, downsized to a smaller apartment in Issaquah, Wash., and came up with $10,000 to fund GreenLink Collective.

The gamble paid off. Sales have doubled each year, Mr. George says, and the couple has opened a second branch.

A classic story, except for what Mr. George sells: marijuana.

It’s legal in less than half the country and still illegal under federal law. It comes with cultural baggage and controversial associations. But a growing number of entrepreneurs like Mr. George are trying to turn cannabis into big business.

Read more: Entrepreneurs Seek Profits From Pot | Wall Street Journal