Two Portland companies will face off against a viewer-picked wild card in the final episode of a Maine-produced reality TV show based loosely on “Shark Tank” next month.

Garbage to Garden, a curbside composting service, and Chimani, a developer of mobile apps for outdoors enthusiasts, earned finalist spots on “Greenlight Maine” at a pitch-off at Husson University in Westbrook last weekend. They were among a dozen innovators who pitched their big ideas to a panel of six judges.

Tyler Frank launched Garbage to Garden in 2012 out of his East End apartment. It has grown from 17 participating households to serving seven towns, including 1 in 7 curbside households in Portland. Chimani’s founders, Kerry Gallivan and Shaun Meredith, have created a portfolio of destination guide apps for national parks and other outdoor areas, including Acadia National Park.

Viewers will select the third finalist from the 26 original competitors for the championship pitch-off, which will be held at 6 p.m. on June 24 at Merrill Auditorium in Portland, by visiting the show’s website, www.greenlightmaine.com. The champion of the pitch-off, which will be broadcast live, will win a cash prize of $100,000. Tickets for the final pitch-off will go on sale soon.

The half-hour show, created by Portland Media Group and organizers of Maine Startup and Create Week, airs on Saturday nights after “Bill Green’s Maine” on WCSH-TV in Portland and WLBZ-TV in Bangor.

“Greenlight Maine” is also soliciting three- to five-minute video pitches for its second season. Pitches are due by Sunday, May 15. Submission information is available at the show’s website.