The Bamboo Farm and Coastal Gardens (BFCG) is a 50-acre extension education center is a top place to visit.

there is also a nice Bonsai Nursery

Hester and Zipperer is a old Savannah Nursery
http://hesterandzipperer.blogspot.com/

The Savannah Garden Exposition is a grand spring event:
http://www.savannahgardenexpo.com/

for daylily:
http://www.joinergardens.com/

Gene's Nursery for Camelias
http://www.camelliashop.com/

Here is a link that might be useful: Bamboo Farm and Coastal Gardens