The most significant botanical difference lies in their flowering habits. Traditional azalea varieties, such as the Southern Indica hybrids or Kurume hybrids, are primarily spring-blooming. They set their flower buds in the late summer and early autumn of the previous year. This means they produce one spectacular, but brief, floral display each spring. In contrast, Encore Azaleas are a hybrid group that blooms on both old and new wood. They initiate their first flush of flowers from spring-blooming buds and then continue to produce new vegetative growth that sets buds and flowers repeatedly throughout the summer and into the autumn. This unique reblooming characteristic is a result of their complex hybrid ancestry, which includes traditional evergreen azaleas and the rare Taiwanese summer-blooming azalea (Rhododendron oldhamii).
From a morphological perspective, there are subtle differences in their form. Traditional azaleas exhibit a wide range of growth habits, from low-spreading types like the Kurumes to large, upright growers like some Southern Indica varieties. Their growth is often more erratic and may require more pruning to maintain a shapely form. Encore Azaleas have been selectively bred for a more uniform, dense, and well-branched growth habit. They tend to be more compact and rounded, filling out nicely without becoming overly leggy. This controlled structure supports their repeated blooming by consistently producing the new stems necessary for flower bud formation.
The foliage of these plants also presents a point of distinction. Many traditional deciduous azaleas drop their leaves in the fall, while evergreen traditional varieties like the Southern Indicas hold their leaves year-round. The leaves of traditional types can sometimes appear pale green or even chlorotic in high pH soils and may not provide significant winter interest. Encore Azaleas are evergreen and are noted for their superior foliage. The leaves are generally darker green, thicker, and more leathery (a trait inherited from R. oldhamii), which offers better resistance to sun scald and environmental stress. Furthermore, many Encore varieties exhibit beautiful burgundy or bronze leaf color in the winter, adding multi-seasonal appeal to the garden beyond their flowers.
A key botanical advantage of Encore Azaleas is their increased adaptability to sunlight. Traditional azalea varieties are notoriously shade-loving, often requiring protection from intense afternoon sun to prevent leaf burn and stress. The genetic influence of Rhododendron oldhamii in Encore Azaleas grants them a significantly higher tolerance for sun exposure. While they still benefit from some afternoon shade in the hottest climates, they can thrive in full sun with adequate moisture, a condition that would typically damage many traditional varieties. This sun tolerance directly fuels their ability to photosynthesize more efficiently, providing the energy required for the demanding process of repeated blooming.
