Vitex (Vitex agnus-castus) is a deciduous shrub that bears clusters of purple flowers in the summer. The leaves of the vitex are reminiscent of the marijuana plant (Cannabis sativa), with five leaflets in a palm-shaped arrangement. The leaves have a fragrance similar to that of the herb sage. The purple flower clusters (called panicles) look like those of the butterfly bush (Buddleja spp.) The black fruit contains four seeds that look like peppercorns and are sometimes used to flavor food.
Like most shrubs, vitex is best planted in the spring to give it plenty of time to establish roots before winter dormancy. It is a fast-growing shrub that can shoot up as much as 7 feet in a single season, but most gardeners opt to keep this potentially invasive plant to 10 feet or less in height.
|Botanical Name||Vitex agnus-castus|
|Plant Type||Deciduous shrub|
|Mature Size||8-10 ft. tall; 5-8 ft. spread|
|Sun Exposure||Full sun|
|Soil Type||Loose, well-drained soil|
|Soil pH||Acidic to slightly alkaline (5.6 to 7.5)|
|Flower Color||Violet, blue|
|Hardiness Zones||6 to 9 (USDA)|
|Native Area||Mediterranean, Asia|
Vitex is an easy-to-grow shrub that poses few challenges to a home gardener. If you avoid soil that is too wet or dense, success is nearly guaranteed. The biggest downside to the vitex is that it may grow too aggressively, requiring frequent pruning to keep it in check. It can, in fact, escape a garden and become invasive if it naturalizes in the wild. This is a problem mostly in certain areas of southern U.S. states—call your local garden center or cooperative extension service to seek advice on growing vitex.
It is commonly used in shrub borders, for foundation plantings, and in butterfly gardens—butterflies and other pollinators love the blooms. In southern gardens, this plant is often used as an alternative to lilacs, which don't grow well in very warm climates. It is also a good choice for xeriscape gardens where irrigation water is used sparingly.
This is one of the only species within the Vitex genus that is native to temperate regions; nearly all others are tropical trees and shrubs. In colder climates (zones 5 and 6), this plant sometimes dies back in winter and is grown as a perennial, in much the same way that the butterfly bush is grown in climates with freezing winters.
Vitex agnus-castus is considered to have invasive tendencies in areas such as Texas, where it has been planted extensively for landscaping.
Vitex will grow well in full sun to part shade, though the best flowering occurs in full sun.
Choose a location where the water drains away instead of gathering. This shrub can handle acidic to slightly alkaline soils but it does not like very rich soil, since this can hold too much moisture around the roots. A native to Mediterranean regions, this plant prefers relatively dry soil. Sandy or rocky soils are no problem.
In most regions, you will not need to water a vitex at all once it is established. In fact, you should avoid using organic mulches, since they hold too much water.
Temperature and Humidity
Vitex agnus-castus may be grown in Zones 6 to 9; it is technically hardy down to about -9 degrees Fahrenheit. But in zones 6, it often is grown more as a perennial plant rather than a shrub, since it may die back to the ground each winter, regrowing in spring. It does equally well in the high humidity of the Southeast U.S. as in the arid climate of the Southwest.
A vitex doesn't require much, if any, feeding. At most, a single application of a general-purpose balanced fertilizer every year or two will suffice.
Several cultivars of vitex are widely sold:
- ‘Abbeville Blue’ grows 6 feet tall with a similar spread. It has deep blue flowers on 12- to 18-inch spikes.
- 'Alba' has white flowers. It is a large plant, growing to 15 feet with a 20-foot spread.
- 'Shoal Creek' is a 15-foot-tall plant with purple-blue flowers and leaves that have good resistance to fungal spots.
- 'Blue Puffball' is a great small shrub, growing only 3 feet tall with delicate blue flowers.
- 'Rosa Ann' is a 15-foot plant with heavily scented pink flowers.
Smaller cultivars for potting include Blue Diddley (grows to 6 feet) and Blue Puffball (grows to 3 feet).
Left unpruned, vitex can become a sprawling, vase-shaped shrub that grows to 20 feet tall with a spread equally as wide. It is sometimes trained as a single-trunk small tree.
You can encourage continued production by deadheading spent flowers—a task that can be a little irksome with larger shrubs. Yearly pruning during winter will help keep the shrub in an attractive shape and control its size. Vitex tolerates heavy pruning quite well. You can train a vitex into a small tree with a single trunk by pruning away completing shoots to encourage a central leader.
In colder climates, this plant is often pruned down right to the ground just before winter. Because it flowers on new wood, your vitex will return to a 3- to 5-foot flowering shrub each year, even with this fierce pruning routine.
The easiest way to propagate a vitex plant is by rooting some branch cuttings. As you might expect with such an easy-to-grow plant, Vitex roots quite easily.
- Clip off a 12- to 18-inch branch tip.
- Cut off the flowering end portion.
- Remove the leaves from the bottom half of the cutting.
- Put the cutting into a vase of water, and set it in a location that receives morning sun but afternoon shade.
- Or, you can also root the cuttings by planting them in a container with moist potting soil.
- Over two months or so, the existing leaves will fall off the cuttings, but the other growth nodes will begin to bud and send out green growth.
- When the bottom of the cutting also begins to develop hairlike roots, the cutting can be transplanted into a pot or a garden location.
Potting and Repotting Vitex
Growing a smaller cultivar of vitex in a pot is easy. Smaller cultivars grow only 3 to 6 feet. You can keep the tree in the same pot for a few years before any repotting is necessary. Follow these simple steps:
- Measure the root ball of the tree.
- Choose a container that is at least 8 inches larger in diameter than the root ball.
- Choose a planter with good drainage or poke several holes in the bottom. Line the planter with landscape fabric to prevent dirt from coming out of the holes.
- Use a quality and well-draining potting mix.
- Add about 10 percent of perlite to the mix to help with drainage.
Common Pests & Diseases
Usually, the only problems you see on Vitex agnus-castus are root rots, nematodes, and leaf spots, though these are not common. Problems usually occur when the soil is not dry enough. Aphids, whiteflies, and scales may also attack, but they are usually easily controlled with horticultural soaps and oils.