Article written by Dr. Gary Knox, North Florida Research & Extension Center – Quincy, FL.
In the times before re-blooming azaleas like Encore®, Bloom-A-Thon® and others, Satsuki azaleas were valued for late flowering that extended the azalea “bloom season”. Even with modern re-blooming azaleas, Satsuki azaleas still are appreciated as refined evergreen shrubs for the sophisticated garden or discerning plant collector.
“Satsuki” means “Fifth Month” in Japanese, corresponding to their flowering time in much of Japan. These azaleas were developed hundreds of years ago from their native Rhododendron indicum and R. eriocarpum. The Japanese selected cultivars more for their form and foliage than for flowering. These beloved plants were used in gardens as sheared boxwood-like hedges or pruned into rounded mounds that might resemble rocks or boulders in classical Japanese gardens. Their size and form also made them well adapted for training as bonsai. Most of the Satsuki azaleas in America were introduced in the 1930s by USDA.
Satsuki azaleas are small evergreen shrubs that flower in April and May in north Florida, long after most older type azaleas have finished. Satsuki azaleas also are known for producing large, mostly single flowers up to 5 inches in diameter in colors of white, pink, red, reddish orange and purple. Often the flowers will include stripes, edging, blotches, spots or flecks of contrasting colors (Sometimes all on the same plant!) with more than 20 different color patterns recorded.
Satsuki azaleas have an elegant subtle charm, quite unlike the flashy, over-the-top, heavy blooming all-at-once Southern Indica azaleas like ‘Formosa’ and ‘George L. Taber’. Typically, Satsuki azaleas display a few large blooms at a time, allowing one to better appreciate their size and color patterns as contrasted against their fine-textured, dark green leaves. To make up for a less boisterous display, Satsuki azaleas flower over a longer timeframe, averaging about 8 weeks, with some flowering an amazing 14 weeks. In another contrast, most Satsuki azaleas grow smaller in size, in my experience reaching about 3 feet tall and wide in a five-year timeframe. The rounded to lance-shaped leaves of Satsuki azaleas also are demure, ranging in length from just ½ inch to no more than 2 inches.
Satsuki azaleas enjoy the same conditions as most other azaleas: light shade and moist, rich, well-drained soil. Mulch regularly to maintain organic matter and help hold moisture. Fertilize lightly and keep the roots evenly moist. Minimal to no pruning is required. Satsuki azaleas also are well adapted to container culture. Their small size and fine textured leaves make these a favorite for bonsai enthusiasts since their small leaves, branching habit and mounded form naturally make them look like miniature mature “trees”.
Sources and Cultivars
Look for Satsuki azaleas in spring at garden centers or year-round at online nurseries. There are hundreds of cultivars but some popular types to look for include:
Gumpo Pink – 3-in. diameter light pink flowers with purplish pink dots and occasional white blotches
Gumpo White – 3-in. diameter white flowers with occasional pink flakes and light green blotches
Gyokushin – 3-in. diameter flowers are predominantly white but with light to dark pink dots and blotches
Higasa – flowers are 4 to 5 inches in diameter and are purplish pink with purple blotches
Shugetsu – also called ‘Autumn Moon’, 3-in. diameter flowers are white with a broad, bright purplish-red border
Tama No Hada – flowers are 4 to 5 inches in diameter and are white to pink with deep pink stripes; usually flowers in fall as well as spring
Wakaebisu – 2.5-in. diameter flowers are “double” (hose-in-hose) and are salmon pink with deep pink dots and blotches; this also flowers in fall as well as spring
Chappell, M. G.M. Weaver, B. Jernigan, and M. McCorkle. 2018. Container trial of 150 azalea (Rhododendron spp.) cultivars to assess insect tolerance and bloom characteristics in a production environment. HortScience 53(9-S): S465.
Galle, Fred C. Azaleas. 1985. Timber Press, Portland, Oregon. 486 pp.