Gretna, FL has a population of 1,457 and is the 12,866th largest city in the United States. The population density is 190 per sq mi which is 35% lower than the Florida average and 110% higher than the national average. The median age in Gretna is 35 which is approximately 16% lower than the Florida average of 42. In Gretna, 47% of the population over 15 years of age are married, 80% speak English and 16% speak Spanish. 70% of Gretna residents were born in Florida, 12% were born out of state, 6% were born outside of the United States and 11% were foreign born.