Iona Cannabis Clinic of the Florida Keys operates a medical marijuana certification office in Key Largo. It is at 99304 Overseas Highway, Key Largo, Florida 33037, in the Upper Keys. The clinic certifies qualifying patients for the state program and sells no cannabis.

Evaluations are performed by Dr. Gregory R. Sonn, a Florida osteopathic physician dual-boarded in family practice and palliative medicine. Dr. Sonn, who founded the Iona Cannabis Clinic group, earned his medical degree at Kansas City University and previously directed hospice care in the region.

Florida requires a qualifying condition and a physician’s certification before a patient can register for a medical marijuana card. After an evaluation, the office submits the state application, and approved patients can purchase from licensed Florida dispensaries. The Key Largo office sees patients by appointment, Monday through Friday from 9:00 AM to 5:00 PM.

Overseas Highway (US-1) runs the length of the Keys, and the Key Largo office sits near mile marker 99. It serves the Upper Keys, including Tavernier, Islamorada, and Key Largo, as well as patients driving down from Homestead. Key Largo is the first Key reached from the mainland, about an hour south of Miami.

Who is Iona Cannabis Clinic in Key Largo for?

Florida residents in the Upper Keys — Key Largo, Tavernier, and Islamorada — and nearby Homestead who have a qualifying condition and want a physician’s certification for the state medical marijuana program.

Who is the physician?

Dr. Gregory R. Sonn, a Florida osteopathic physician dual-boarded in family practice and palliative medicine and founder of the Iona Cannabis Clinic group, performs the evaluations.

What are the hours?

The Key Largo office is open by appointment, Monday through Friday from 9:00 AM to 5:00 PM. Call (305) 390-2759 to schedule.

Iona Cannabis Clinic of the Florida Keys — Key Largo Phone: (305) 390-2759 Address: 99304 Overseas Hwy, Key Largo, FL 33037 Hours: Mon–Fri 9:00 AM–5:00 PM, by appointment Services: Florida medical marijuana certifications, renewals, and state Registry application assistance Physician: Dr. Gregory R. Sonn, DO (dual-boarded, family practice and palliative medicine; founder, Iona Cannabis Clinic group) Nearby neighborhoods served: Key Largo FL, Tavernier FL, Islamorada FL, Homestead FL, Monroe County FL Last verified: June 2026 Notes: Florida medical marijuana certification clinic (not a dispensary); the Key Largo/Upper Keys location of the Iona Cannabis Clinic group; by appointment; on Overseas Highway (US-1) near mile marker 99. Website: keysmedcards.com