HCMG Plant of the Month: Vitex Agnus–Castus
By Becky Lowicki, Master Gardener
Everything, everywhere, all at once!
With the inundation of pollen season, buds of greenery peeking out from everywhere, and so much to do to tidy after winter, the feeling of everything needing attention instantly is apropos for any garden on the cusp of spring!
From sprucing to planning to planting, it’s hard to know where to begin as there seems to be endless tasks as well as excitement to get ahead of the Houston heat that will be upon us before you know it.
Texas Superstar© Status
An outstanding, Texas Superstar©, Vitex agnus–castus, also known as Texas Liliac Vitex or Mexican Lavender, is one option providing both a showy and colorful addition as a proven hardy survivor of the Houston heat with ongoing visual appeal throughout the blooming season.
A native of China and India, it has been naturalized throughout some U.S. regions, with records dating to its cultivation in the U.S. since 1670.
The detail of the bark gives a minimalist look similar to that of crepe myrtle with bountiful lavender blooms that attract pollinators galore at the height of its blooming profusion.
Historically, Vitex agnus-castus belonged to the official medicinal plants of antiquity and was mentioned in the works of Hippocrates, where use of the plant for injuries and inflammation, among other remedies was noted.
Versatile and adaptable in both acidic and alkaline soils, Vitex grows best when planted in full sun, tolerates partial sun and prefers a location that drains well as it thrives in hot and dry environments.
Favored by the Texas Department of Transportation for its toughness, Vitex, with its indigo blooms, is often spotted along highway medians where it is a top performer. A popular pollinator, the butterfly-attracting plant is also known to be deer-resistant.
While older cultivars had small spikes of flowers which were pale lilac, mauve, off-white or light pink with smaller, nonde- script flowers, improved varieties such as “Montrose Purple,” “LeCompte,” and “Shoal Creek” – all of which are marketed as Texas Lilac Vitex – boast fragrant, larger, long-lasting cut flowers amidst long spikes reaching 8 to 12 inches.
Care
Vitex has a very rapid growth rate and will become a small tree quickly reaching heights of 10 to 15 feet tall and up to 15 feet wide if not pruned judiciously. Flowering is also more spectacular if the plant is pruned annually every winter to keep the plant manageable.
With a bloom time of May until frost, many aromatic black or dark-brown seeds are produced after petals have dropped, which may result in a reduction of additional bloom spikes or produce a seedling population that will not have the same characteristics as the original plant and become a nuisance.
To address any potential bloom reduction, simply cut off or deadhead the spent bloom spikes promptly after flowering so that the shrub will bloom again. Depending on weather and cultural conditions, plants will bloom repeatedly within six weeks of seed pod/stalk removal.
To stimulate rapid re-blooming and larger flower spikes, three pounds of a slow-release formulation of lawn fertilizer (19- 5-9) per 100 square feet is recommended around each plant after spent blooms have been removed. The sooner the seed pods are removed before they harden, the faster the plant will begin the re-blooming process.
From butterflies to blooms, as a drought-tolerant, pest-resistant plant, Texas Lilac Vitex offers both beauty and beneficial attributes across any home landscape.
Source: Harris County Master Gardeners Urban Dirt Newsletter (April 2023 Edition)
About Urban Dirt
Each month, Harris County Master Gardeners publishes an informative, resourceful newsletter entitled "Urban Dirt". This article was derived from the April 2023 edition. To read the April 2023 edition of this newsletter, click the button below.
