I found the following article posted on the Ag Extension website from Lee County, NC concerning some cold-hardy citrus planted there several years ago:
http://lee.ces.ncsu.edu/index.php?page=news&ci=LAWN+79
I recently contacted the Ag Extension office in Lee County to see how the test plot had fared in the three years since the article was published. Here's the reply I received from NC State's Horticultural Science Professor Dr. Dennis Werner through the Lee County Ag Extension Director Susan Condlin:
I do have a very small Citrus planting at the Sandhills Research Station. It is not a formal trial planting, but an experimental planting of a hybrid population derived from a cross of pummelo (grapefruit relative) and Poncirus (a cold hardy citrus species). The work is being done in conjunction with the University of Florida, as they are interested in trying to develop a cold hardy grapefruit variety. Basically, they send seeds up here from their crosses, I germinate them, grow them at the Sandhills, and see what lives after our cold winters. At this time, I only have 5 surviving plants at the research station, from an initial population of around 200 plants, a reflection of the losses due to cold injury and the small nature of the study.
-Tim
