TROPICAL PLANT ENCYCLOPEDIA
Trachelium caeruleum
Blue ThroatwortFamily: Campanulaceae
Origin: Mediterranean
USDA Plant Hardiness Zone Map
Trachelium caeruleum remains evergreen in our climate but can be treated more as a semi-hardy deciduous perennial elsewhere, possibly tolerating temperatures as low as 0° F or as a long blooming annual in even colder climates.
Link to this plant:
https://toptropicals.com/catalog/uid/trachelium_caeruleum.htm