These are the laws you need to know to safely, legally and responsibly use marijuana:

If you're under 21, it's illegal.

In order to buy, have, or use retail marijuana in Colorado, you must have a valid ID proving you’re 21 or older. It’s a felony to give or share marijuana with someone younger than 21 years old. This includes family members and friends.

Marijuana use by non-U.S. citizens is a felony.

Although marijuana is legal in Colorado, if you’re not a U.S. citizen you can get in serious trouble with the federal government. Permanent legal residents and those with immigrant status should know how the law affects them. This video has the information that you need to know.

It's illegal to use in public.

Using marijuana in any form (smoking, eating, or vaping) isn’t allowed in public places. That includes ski resorts, sporting and music venues, state and national parks, campsites, playgrounds, sidewalks and roads, dispensaries, bars, restaurants, and outdoor or rooftop cafes. Keep in mind that property owners, landlords, and rental companies can ban people from using or having marijuana on their premises. Make sure you check the rules before you use.

Federal land is off-limits.

Marijuana is legal in Colorado, but it’s not legal federally. That means if you’re on federal lands, such as a national park or a national forest in Colorado, you can’t use marijuana or have it in your possession.

Marijuana cannot leave the state.

It’s illegal to take or mail marijuana out of state. Carrying marijuana is also banned at all Colorado airports, so leave your marijuana at home when packing for the airport. And if you’re visiting, make sure you have properly thrown away any marijuana before you arrive at the airport.

Driving high can lead to a DUI.

Driving under the influence of marijuana is illegal and could lead to a DUI charge. Under Colorado marijuana driving laws, you can’t drive if you have five nanograms or more of THC in your system. If you’re smoking, wait six hours before driving. If you’re eating or drinking a product with THC, wait eight hours.

1 ounce is the limit.

Adults over the age of 21 can purchase and have up to one ounce of marijuana on them at a time.

Marijuana must be kept sealed in your car.

If you have marijuana in your car, make sure it’s sealed and unused. It’s illegal to open and use any marijuana in a vehicle. That goes for both the passenger and the driver.

Where to buy marijuana in Colorado.

Licensed retail locations are the only legal place to buy marijuana in Colorado. It’s illegal for anyone to sell marijuana without a state and local marijuana business license. It’s also illegal to buy marijuana from anyone who doesn’t have a license to sell it.

If you choose to grow, know the Colorado weed laws.

Coloradans can grow marijuana for personal use. A Colorado resident over the age of 21 can grow up to six plants, with as many as three plants flowering at one time. You must grow plants in an enclosed, locked location. All residences are limited to a maximum of 12 plants, unless you are a registered medical marijuana caregiver. Be sure to check your local laws for specific details.

Only medical patients can buy medical marijuana.

Patients with qualifying debilitating medical conditions can receive a medical marijuana card for legal access to medical marijuana. Cards are available to Colorado residents and are only valid in Colorado. See Colorado medical marijuana license information.