What major geographical advantage does agriculture in the Coastal South have over most other regions of North America

The region is largely frost-free so many frost intolerant crops can be grown.

Explanation:

The Coastal South in North America consists of cities like Florida, Texas, and North Carolina. This region is known for the exceptional agriculture that occurs there. The nature of their soil is not the cause of this, rather it has a lot more to do with their climatic conditions which range from the time of the last frost in spring to the beginning of the next frost in fall. So, this allows for about nine months of intensive agriculture.

Frost is ice which is mostly seen on the surface of the soil. It is quite difficult for many plants to survive the harsh condition imposed by frost. So the lengthy number of days and months without frost in the Coastal South gives it a great advantage over compared to many other regions in North America.