If you missed the boat on the recent gold and silver rally, fear not. Dennis Gartman says there's a different commodity that could give your portfolio a major boost in the coming weeks.

"Take a look at what's happening to cotton," the editor and publisher of "The Gartman Letter" said on Tuesday on CNBC's "Futures Now." "It's a market that nobody has been paying attention to and has been totally left off of everybody's radar."

Cotton futures are up nearly 19 percent in the last three months and are trading at levels not seen since June 2014. Those gains over the last few months are double what we have seen in gold and oil, which are both up roughly 7 percent in the same period. Year to date, cotton is up nearly 12 percent.

Gartman, whose first job out of graduate school was serving as an economist for Cotton Inc., says that the commodity has wrongfully received a somnolent reception in today's market. He added that in the past two weeks, the planted acreage for cotton was 10 million acres, which is far above the usual amount. From here, Gartman believes that news should have set up for a "very bearish report, and yet the market took that very well," as the data has been largely discounted by the market.

"Something is developing technically in the cotton market. Cotton is trading within a very small range between 68 cents and a low of 60 cents," explained Gartman. "Suddenly, cotton is breaking out to the upside. The term structures are starting to move and the contangos are beginning to narrow. Markets that don't go down on bearish news aren't going down anymore."

To Gartman's point, cotton has made a significant week-to-date surge of 7 percent, on pace for its best weekly performance since 2012.

"Any time you have a chance to buy any weakness in the next two or three days, take a look at it," Gartman urged. "Be a buyer on any one- or two-cent declines."