Adult-use, or recreational marijuana, is legal in Michigan as of November 2018. Proposal 1 made Michigan the first state in the Midwest to legalize the possession and use of recreational marijuana for adults (age 21 years or older).In Michigan, adults may grow up to 12 marijuana plants at their own residence for their personal use. Individuals: Individuals anywhere in Michigan may now use marihuana for individual recreational purposes, as long as they comply with the Act. Michigan became the 10th U.S state to legalize recreational use of cannabis in 2018.