In Montana, you can have up to 1 ounce of flower a day and up to 5 ounces a month with a valid medical marijuana card. An ounce of flower is equal to 800 mg of THC in infused products or 8 grams of THC in concentrate.
Patients who need more than 5 ounces a month can submit a petition (approved by their provider) to increase their purchase limit to 8 ounces a month.
Patients can also grow up to 4 mature plants and 4 seedlings for personal use. If there are two or more medical marijuana patients in the same residence, the maximum allowed is 8 mature plants and 8 seedlings.
Montana residents 21 and older can possess up to 1 ounce of marijuana and grow up to 2 mature plants and 2 seedlings for personal use.