In California, there is no express limit on the amount of medical marijuana a patient can possess.
However, there may be legal implications should a patient possess an amount indicative of selling or trafficking.
Leafwell recommends you speak with an attorney if you may have a need to possess medical marijuana in a quantity greater than an amount reasonable for personal, daily consumption.
The generally accepted, non-official limit for medical marijuana patients is 8 ounces on their person, or up to 60 grams of cannabis concentrate (1 oz. being equivalent to 8 grams).