LSU AgCenter Horticulturist
If you've admired the stunning display of purple flowers in the landscape in recent weeks, you've witnessed one of Louisiana's finest blooming small trees or large shrubs: the vitex, also known as the chaste tree.
The Oxford Dictionary defines chaste as “without unnecessary ornamentation; simple or restrained.” True to its name, the chaste tree is simple in its ease of care but far from being plain.
The name vitex has its origins in a Roman book titled “Naturalis Historia,” where the author noted that women in Athens kept branches of the tree under their beds during the feast of Ceres, the Roman goddess of agriculture, grain and fertility.
Vitex trees can be found blooming across the state this time of year. These large, deciduous, flowering shrubs are often considered small trees. They put on a stunning show from late spring through summer with their beautiful bluish-purple flowers clustered in tall spikes. These trees bloom every year with minimal effort from the gardener for about a month. In good years, you may get a second bloom in late summer or early fall.
Chaste trees produce showy, 5-to-7-inch spikes of small, lavender-blue flowers from late May through June in Louisiana with a second flush of flowers in July or early August. Other colors are available. There are cultivars with white flowers like Alba and Silver Spire, and Rosea and Galactic Pink have pink flowers.
One of the most favored cultivars is Shoal Creek, a Louisiana Super Plant selection, known for its lighter purple flowers. A couple of dwarf cultivars are Delta Blues and Blue Puffball.
Vitex trees should be planted in full sun for the best blooms, but they also do well in partial shade. They are typically winter hardy in USDA zones 6 to 9. These plants grow to 10 to 15 feet tall by 15 to 20 feet wide. Their growth rate is vigorous in loose, well-drained soil that is a bit on the dry side. In fact, they are very drought-tolerant once established. In wet soils, chaste trees can suffer from dieback and root rot and occasionally get leaf spot, but they have no major pest concerns.
When allowed to grow naturally, vitex will generally form a large, bushy plant about 10 feet tall. If you prefer a more compact form, you can cut the plant back to about 2 to 3 feet from the ground in late winter.
In addition to their beautiful flowers, vitex trees have attractive, star-shaped, aromatic leaves. When you brush against or crush the leaves, they emit a crisp, clean scent similar to sage. The leaves are green-gray on top and gray underneath, growing in a palmate pattern with five to seven lance-shaped leaflets emanating from a single point.
Vitex trees make excellent focal points in the landscape. When in bloom, they not only catch the eye but also attract pollinators. Bees, butterflies and hummingbirds are often seen feeding on the sweet nectar of the trees. Additionally, the seeds attract several small bird species.
Chaste trees are deciduous and may lose their leaves during extended cold snaps. However, they do not remain bare for long, thanks to their fast growth rate. Harder freezes may cause some dieback and damage, but the trees quickly recover.
While vitex is a nonnative species and can be considered invasive due to its seeds colonizing nearby landscape beds, removing the old flower spikes to prevent seeds from forming can help control its spread. The plant can also be easily reproduced by cuttings.
Shoal Creek stands out as an exceptional selection of vitex with superior characteristics. Its 12-inch flower spikes are noticeably larger, with a deeper, more vibrant lavender-blue color. It has exceptionally vigorous growth, quickly filling your landscape with beautiful and aromatic leaf growth and gorgeous flower spikes.
For gardeners who prize plants that require little care but offer a beautiful display, the chaste tree is an excellent choice. Local nurseries and garden centers often carry Louisiana Super Plants, so look for Shoal Creek vitex there. To learn more about the Louisiana Super Plants program and find participating nurseries near you, visit www.lsuagcenter.com/superplants.
Shoal Creek vitex is a Louisiana Super Plant and is a superior selection for the landscape. Photo by Heather Kirk-Ballard/LSU AgCenter
Chaste trees produce showy, 5-to-7-inch spikes of small, lavender-blue flowers from late May through June. Photo by Anna Ribbeck/LSU AgCenter
Chaste trees make a great accent planting for the landscape. Photo by Anna Ribbeck/LSU AgCenter