Too Legit to Quit? Medical Marijuana Dispensaries are Filling Storefronts and Making It Safer for Patients with Legitimate Needs. But Cities are Challenging the Propriety of Health Care's Latest Strain

On a sunny Saturday in January, 72 people paid $250 each to hear Dana May--aka "Professor Marijuana"--divulge the secrets of successful cannabis cultivation. The self-proclaimed best grower on the planet, May tells the group he can produce in 43 days what typically takes four to five months, from start to finish, seed to weed. He has three rules, and the first of which--and possibly most important--is the KISS principle: Keep It Simple, Stupid.