Possession limits in Massachusetts only differ for public possession. MMJ patients may purchase up to 10 ounces at a time, so they can possess up to 10 ounces in public where an adult user can only possess one ounce. (The amount of cannabis concentrate on their person must not be over five grams at a given time.)

At home, registered qualifying patients in Massachusetts may possess up to a 60 day supply of cannabis, which the Commission determined to be 10 ounces. This happens to also be the same amount of cannabis that an adult-use cannabis consumer can possess at home.

In both cases, patients and adult users can possess the cannabis they cultivate at home in addition to what they purchase.

The distinction between how much cannabis can be grown by adult-use consumers vs. recreational consumers is also rather muddled. The regulations state that registered medical cannabis patients may grow enough marijuana to yield their 60-day supply, or 10 ounces; but adult-users can grow up to 6 plants, or up to 12 plants if two adult-users live in the house.

Since Massachusetts residents are also allowed to possess "up to 10 ounces of marijuana and any marijuana produced by marijuana plants cultivated on the premises," the actual possession limit for what you can possess at home is basically the same for patients and adult-users, or 10 ounces of purchased cannabis plus whatever they legally grew themselves.