I am frequently asked if there is any citrus plant that can be grown outdoors year-round in Atlanta.
Unfortunately, there is none. Freezing temperatures doom them in winter.
Further south, gardeners tell tales of certain citrus that “has grown in Mama’s garden for years. And it makes the best fruit juice you ever tasted!”
Dr. Mark Reiger decided to put these anecdotal tales to the test and perform a multi-year study of several different citrus plants grown outdoors.
He chose Savannah, GA as a spot not as cold as north Georgia, but colder than citrus country in Florida.
There are still no citrus that can survive outdoors in Atlanta. However, there are certain mandarin, satsuma, citrangequat and orangequat cultivars that might be suitable for south Georgia.
If you want to try, these folks offer a lot of information and selection.