Under Prop. 215, patients are entitled to whatever amount of marijuana is necessary for their personal medical use. However, patients can be arrested if they exceed reasonable amounts and they can be cited or fined for exceeding local laws. Under MMRSA, which took effect Jan. 1, 2016, qualified patients can cultivate up to 100 square feet for personal medical use, and primary caregivers with five or fewer patients are allowed up to 500 square feet. Exemption under this section does not prevent a local government from further restricting or banning the cultivation of medical cannabis.
https://www.canorml.org/medical-marijuana/patients-guide-to-california-law
https://www.canorml.org/news/A_SUMMARY_OF_THE_MEDICAL_MARIJUANA_REGULATION_AND_SAFETY_ACT
Although new laws have allowed whatever is justifiable medically, traditionally the limit has been 8 ounces and we recommend that you keep things within this range. Law enforcement can always chose to scrutinize you if they feel as though you are not in compliance.
ryan