Colorado lets adults 21 and older buy, hold, and use recreational cannabis, but the state pairs that right with firm limits. Adults may carry up to 1 ounce of flower or up to 8 grams of concentrate, may grow a small number of plants at home, and may only buy from licensed stores. Public use, driving under the influence, and carrying cannabis across state lines remain illegal.
Colorado cannabis limits at a glance
- Minimum age: 21 for recreational, 18 for medical with a valid state card.
- Public possession cap: 1 ounce of flower or 8 grams of concentrate.
- Retail purchase cap: 1 ounce flower equivalent per person per transaction.
- Home grow: 6 plants per adult, 12 plants per household.
- Public consumption: illegal on sidewalks, in parks, in vehicles, and in most businesses.
How to buy cannabis legally in Colorado
- Confirm you are 21 or older and carry a valid government photo ID. Patients aged 18 to 20 need a Colorado medical card.
- Pick a store that displays a current Marijuana Enforcement Division license at the entrance.
- Stay inside the single-transaction cap: 1 ounce of flower, 8 grams of concentrate, or a mix that equals 1 ounce.
- Pay with cash or the store's approved method. Card payments vary by shop because cannabis remains federally illegal.
- Leave with the product in a sealed, child-resistant package and keep it sealed until you reach a private address.
Possession and home grow rules
The 1 ounce public limit counts flower and its equivalent together, so a buyer cannot stack an ounce of bud with a full gram of shatter in public. At home, adults 21 and older may keep more than the public carry limit only if it was grown on site and stays on private property. Home grows must sit in an enclosed, locked space and stay out of public view. Medical patients with an extended plant count need a doctor's recommendation and state registration before exceeding the standard household cap.
Where cannabis use is not allowed
Smoking or vaping in public is a petty offense and can draw a fine. That covers parks, trails, sidewalks, ski lifts, and inside a parked car on a public street. Landlords and employers may ban use on their property, and several cities and counties prohibit retail sales outright, so check local rules before you travel. A small number of licensed hospitality businesses allow on-site consumption, but they are the exception.
Driving and moving cannabis
Driving with a THC blood level of 5 nanograms per milliliter or higher can support a driving-while-impaired charge. Keep all cannabis in a closed, sealed container in the trunk or a locked glove box, never in reach of the driver or in an open package. Open containers in the passenger area are prohibited even if the driver has not used any.
Medical cannabis differences
A valid Colorado medical card raises the daily purchase limit to 2 ounces and allows patients as young as 18 to buy without a recreational age requirement. Patients register with the state, pay a fee, and list a recommending physician. Caregivers may grow for patients, and the plant count rules follow the patient's registration.
Federal law and crossing state lines
Cannabis stays illegal under federal law. Do not carry it onto a plane, mail it, or take it into another state, including one that has its own legal market. Federal land such as national parks and forests follows federal rules, so possession there is a federal offense even inside Colorado.