Hi sara. I am that member. I have family in Virginia Beach so I'm very familiar with the area.

Rhododendrons seem to be sold by nurseries from roughly your area, up to Maine on the US east coast. But what buyers should ask themselves (before buying any permanent planting material in a nursery) is: do I see these in local gardens? The fact is you just don't in SE Virginia. Imagine a line from DC down to a little west of Charlotte, NC. South and east of that line you just aren't going to encounter many traditional elepidote rhododendrons like the ones you listed. There might be a smattering them in collector's gardens and arboreta. For example I was at the Raulston Arboretum in Raleigh this spring. In spite of a zeal to collect many, many rare and common Asian BLEs (broadleaved evergreens) there were only a couple mature Rhododendrons of commerce (i.e., not Azaleas) in their lathe house. They looked healthy - at least one of them was a Taiwanese species, R. formosanum IIRC. OTOH, there are neighborhoods in the Main Line suburbs of Philadelphia where every 3rd house will have a large 10' Ironclad or Dexter rhodie!

The better Taiwanese species to impart root rot resistance is R. hyperythrum. The Southern Living 'Southgates' are patented versions of hybrids between various Ironclads and that species. This is based on pioneering work of John Thornton in Louisiana. Here is his original article discussing his work: https://scholar.lib.vt.edu/ejournals/JARS/v44n2/v44n2-thornton.htm

Amazingly he was still alive and sending seedlings to Rarefind as recently as about 10 years ago, but I think his work is now being carried on by others. (In the interest of fairness I want to mention that a woman named Sandra McDonald was trying to create similar hybrids in Norfolk, VA, but I don't think any of them ever made it to market. Thornton might have just had a head start. She is somewhat better known for her azalea crosses.)

So, basically, like Gardengal alluded to, if you want a rhodie to survive in SE Virginia, get either 'Charles Loomis', another one of the other older non-patented hyperythrum hybrids like 'Opal Thornton', or the newer, patented Southgates. You are more likely to find the latter. However it seems to me like maybe the Southgates haven't really taken off. It could just be that nurseries are too lazy to order what they should. Honestly I think from DC to anywhere south, nurseries have no business selling traditional varieties because they just aren't going to last. And remember, even the Southgates have to be planted on well-drained soil, with afternoon shade but some morning sun to help them bloom. Make sure to aggressively open up and splay the roots of a container grown plant to make sure you don't create the 'bathtub' effect by just plopping it in a hole. Fall planting would be better in your climate.

And this whole thread is eerily timely because I'm sending a bunch of cuttings of 'Charles Loomis' to David Parks, owner of Camellia Forest near Raleigh, to root. So they should be for sale there in a few years. But call around, you can probably find at least one decent nursery in SE VA or eastern NC selling the Southgates. Good luck!