Exciting Flowering For Landscapes
by Doug Caldwell, Ph.D.
Commercial Landscape Horticulture Extension Agent
University of Florida Collier County Extension Service
The Clerodendrum genus is made up of about 400 species, and includes evergreen shrubs, trees, and a few vines from tropical areas around the world. Formerly in the vervain family (Verbenaceae), they have recently been moved to the mint family (Lamiaceae). An important fall-winter seasonal gap is filled by many species in this group because of their late-season burst of blooms.
Blue Butterfly (C. ugandense)
Some of the common clerodendrum species include the lovely blue butterfly (C. ugandense); the viney bleeding heart (C. thomsoniae), the spectacular ‘Winter Starburst’ (C. quadriloculare), and 2 new white-flowering types, nodding clerodendrum (C. wallichii) and ‘Musical Note’ (C. incisum macrosiphon). Two fairly common red-orange species are the horizontally-tiered pagoda flower (C. paniculatum) and the Java glorybower (C. speciosissimum).
‘Musical Note’ clerodendrum is a winner from several standpoints. At just 3 to 4 feet tall and 4 to 5 feet wide, it is a short shrub that does not need shearing. I saw a hedge of this under-used species in a strip mall where the prevailing “shearing madness” kept them shaped into little “boxes” with no flowers to enjoy. This repeat bloomer produces flowers almost monthly, if left unsheared. As with many of the clerodendrum species, the flower has outrageously long stamens that add to the delicate appearance and interest as they extend outward about 1.5 inches beyond the flower petals. The unique flower buds have a soprano-range shaped, eighth-note appearance. If sooty mold develops, look for aphid infestations on the new growth.
The nodding clerodendrum is an upright (not bushy), charming shrub that grows to about 7 feet and has attractive, dark-green, glossy leaves, 4 to 9 inches long. The flowers are held in dangling, 10- to 18-inch panicles that appear in cascades of white in early November. Unfortunately, this is not a repeat bloomer, but the attractive foliage makes it interesting year round. Keep it out of windy locations and avoid putting it where it will get direct, late-afternoon sun.
‘Winter Starburst’ is a multipurpose plant from the Philippines. In his book, The Tropical Look, Robert Riffle states, “It is arguably the most beautiful species in the genus.” It forms a nice small tree (to 15 feet tall and 8 feet wide), with dark-green, foot-long leaves that have striking dark reddish-purple undersides. The spectacular, 12-inch flower heads are like firework bursts of white-pink that explode around Christmas through January. The display hangs in there for about 6 to 8 weeks. This species should be used with caution. I planted 2 small plants and within 4 years I had an unplanned hedge engulfing the back of my house! This plant suckers readily, and I was too enthralled with it to rip the suckers out.
Java Glorybower (C. speciosissimum)
Clerodendrum Chinese (C. chinese) (invasive)
Clerodendrums are listed as zone 10b-11 plants, and are not recommended for north Florida’s zone 8. In central Florida’s zone 9, they can be damaged or killed by cold temperatures, but will often survive, unscathed, from year to year, especially if provided some cold protection, such as planting in a higher area of the landscape, under canopy, or by water or buildings.
Pagoda flower, Java glorybower, and ‘Winter Starburst will spread invasively. Bleeding heart will “twine” into nearby trees and shrubs. Two other clerodendrum species, C. bungei (cashmere bouquet) and C. chinense (stickbush) have attractive flowers, but are so aggressively invasive that they are not recommended.
Plant in well-drained, fertile soil in partial shade. Mulching will help keep soil moist and cool. Clerodendrums are not salt tolerant. Propagation is by cuttings, air layering, or seed.
Musical Note (C. incisum macrosiphon)
Winter Starburst: Clerodendrum Quadriloculare