Scotts Miracle-Gro Co. has long sold weed killer. Now, it's hoping to help people grow killer weed.

In an unlikely move for the head of a major company, Scotts Chief Executive Jim Hagedorn said he is exploring targeting medical marijuana as well as other niches to help boost sales at his lawn and garden company.

"I want to target the pot market," Mr. Hagedorn said in an interview. "There's no good reason we haven't."

Sales at Scotts rose 5% last year to $2.9 billion. But the Marysville, Ohio, company relies on sales at three key retailers— Home Depot Inc., Lowe's Cos . and Wal-Mart Stores Inc.—for nearly two-thirds of its revenue. With consumers still cautious about spending, the retailers aren't building new stores as quickly as they used to, making growth for suppliers like Scotts harder to come by. Against that backdrop, Mr. Hagedorn has pushed his regional sales presidents to look for smaller pockets of growth, such as the marijuana market, that together could produce a noticeable bump in sales.

Sixteen states have legalized medical marijuana, the largest being California and Colorado. The market will reach $1.7 billion in sales this year, according to a report by See Change Strategy LLC, an information data services company.