As states increasingly legalize marijuana use, the pot industry has started plowing more money into shaping federal policies.

In the first six months of 2017, the marijuana industry spent $450,000 on lobbyists, double the amount it did in the same period a year earlier, according to a recent report from the Center for Responsive Politics, which tracks lobbying expenditures. The analysis was based on publicly filed disclosure forms.

While companies in other sectors spent far more, the growth rate of marijuana lobbying was the highest of any industry.

"Whenever you see industry that didn't used to be regulated becoming regulated, you are going to see a lot of people wanting to influence those regulations," said Sarah Bryner, the Center for Responsive Politics' research director.

Much of the increase stems from spending by Scotts Miracle-Gro Co., the Ohio-based garden products company that is making a big bet on legalized pot. Scotts "has emerged as one of the biggest players in the traditional business to publicly establish a foothold in the ancillary wings of the cannabis industry," according to the Cannabist, an industry publication.

Disclosure reports show that Scotts spent $210,000 on lobbying in the first six months of 2017, which is $90,000 more than in all of 2016. The Scotts lobbying money went to two Washington firms: the Podesta Group, co-founded by Hillary Clinton campaign Chairman John Podesta; and BGR Group, whose founding partner is former Republican National Committee Chairman Haley Barbour.

At least 29 states and the District of Columbia have laws allowing some form of marijuana use. Most of those laws require doctors' permission, but eight states have passed laws allowing some forms of recreational use.

Tony Mecia is a senior writer at The Weekly Standard.