You can read about our interest in Southgate rhododendrons over here. The brief story is rhododendrons at lower elevations are not protected from the various problems that bedevil gardeners in the deep South who wish to grow rhododendrons successfully. (See the admittedly presumptuously titled 'Your Rhododendron Has Died. An Explanation' for more information as to the reasons behind the problems.)
In our third year of testing, so far the Southgate rhododendrons have done swell both in the pot and in the ground. The attached photo is one of this year's blooms. Each shrub is absolutely packed with flowers. Southgate rhododendrons thus far are highly recommended.