After lengthy negotiations with Lionsgate, Showtime has closed a deal for an eighth season of comedy Weeds. Production on the 13-episode eighth season will start next year for a 2012 launch. Weeds, created by Jenji Kohan, is the longest-running series on Showtime and the most watched comedy. It stars Mary-Louise Parker as a suburban widow-turned- full-fledged marijuana queenpin. Justin Kirk, Hunter Parrish, Alexander Gould and Kevin Nealon co-star.