While botanists classify azaleas and rhododendrons in the same botanical genus, gardeners make a distinction between them in both their culture and usage. Rhododendrons are usually considered more difficult to grow than azaleas, but that long believed convention may be misguided. Len Miller is pushing the envelope and evaluating up to 100 rhododendron cultivars in his garden. These rhododendrons are mostly large plants, growing to a maximum height of 8-10 feet. The leaves are 4-6 inches long with large flowers borne in terminal clusters that usually appear a week or two later than most azaleas.
Flower colors range from purple to red, pink and white.
Hundreds of selections and hybrids have been made of rhododendrons, and in recent years they ve been shipped in large numbers from Oregon nurserymen to garden centers throughout the country. The suitability of many of these selections to our Southern climate is uncertain, so do some homework before buying, or buy a single plant for a trial in your own garden. Preparing the soil for rhododendron plantings requires the addition of lots of organic matter on top of the existing soil. Len Miller prepared his beds by hauling in a 2-foot layer of chipped limbs a year in advance of planting and allowing this to compost down. After six months of composting, he tilled the chipped limbs to speed the composting process.