In this Thursday, April 12, 2018, photo, a worker walks into a greenhouse growing cannabis plants at Glass House Farms in Carpinteria, Calif. Greenhouses that once produced flowers are seen as ideal for growing marijuana. In a climate like Carpinteria's, they heat and cool easily and inexpensively, and the plants thrive. It takes only about three months to grow cannabis in pots of shredded coconut husks, so farmers can get multiple harvests each year. (AP Photo/Jae C. Hong)