I receive a few phone calls every year from people who want me to identify “that tree with purple blooms, looks like a lilac.” That beauty, my friends, is Vitex agnus-castus, commonly called “Chaste tree.” Vitex can be described as a large deciduous shrub or a small tree. Cold-hardy from zone 7b to 11, Vitex tolerates any type of soil and is very drought tolerant once established. They will not survive boggy soils, so err on the side of less irrigation rather than more.
Vitex blooms smell sweet and their five-fingered leaves (resemble marijuana) have a pleasant sage-like fragrance too. The odor means that deer usually leave it alone.
Vitex forms a multi-stemmed tree but can be pruned to a single trunk if the gardener is so inclined. The lavender blooms appear at the ends of branches and point upward, making them look like a cousin to Clethra. Our region is becoming saturated with Crape Myrtles. I love the Crapes, but wish that more people would plant Vitex because of its benefit to pollinators. Butterflies and bees flock to the blooms. They are frequently planted near beehives to increase honey production. There is no fall color to mention, but the loose, rounded crowns have a special charm. They are quick growers, reaching a mature height of 25 feet. Plants thrive in heat, in full sun or part shade. I think they look best as an under story tree, in the partial shade cast by larger trees. A neighboring town used them in the central median plantings along a major highway, which confirms their hardy nature.
The Vitex in the Mary Snoddy garden is at least fifty years old, maybe more. It is starting to show the effects of old age, with a few branches dying here and there. When it reaches the end of its life, I plan to replace it with another specimen of the same type. ‘Shoal Creek’ has the typical lavender bloom, but ‘Alba’ is white and ‘Rosea’ has pink flowers. Several blue cultivars are available, and so are dwarf forms.
I was surprised to read that Vitex is considered invasive in certain areas of the Carolinas and several southwestern states. I have not seen that in my own garden, nor have I seen them proliferate in ungroomed areas.
If Vitex has a drawback, it is that the limbs tend to droop with age. While graceful, this creates difficulty in lawnmowing nearby. The thin bark is easily damaged by string trimmers. Surround them with a ground cover to eliminate the need to prune low-hanging limbs. A grass-like ground cover like Mondo Grass (Ophiopogon) tolerates shade cast by the tree and has the added advantage of absorbing the fine leaves shed in fall. No raking – Yay!