Vitex trifolia "Purpurea" is a native of Southeast Asia and Australia. It is known by common names including Arabian lilac or chastetree. Whether you use this shrub as a foundation shrub, a single specimen or group several together as a hedge, the fuzzy, lavender-tinged foliage and purple flower clusters are breathtaking. The fragrant flowers attract butterflies and bees. Arabian lilac is an evergreen broadleaf shrub; it drops old leaves in the spring when the new season's leaves emerge, so it adds texture and interest to your landscaping all year. Pruning invigorates this shrub. Arabian lilac blooms on new wood, so prune it in the winter or early spring before new growth begins.
Things You'll Need
Hedge clippers, optional
Shape the shrub to the desired form with hand pruners. Allow wandering branches to cascade, if desired, but clip some of the tips to encourage new growth. Remove old wood that bore blossoms the previous summer to make room for new growth, which produces new blossoms.
Prune any broken or damaged branches whenever they are noticed. Open the center of the shrub to allow light to penetrate, encouraging denser new growth and more flowers throughout the plant.
Prune short foundation shrubs heavily to limit upward growth. You can train Arabian lilac as a low-growing shrub to cover large areas or slopes by selecting branches to train as lateral cascading or spreading limbs.
Clip the shrubs into a flat or rounded hedge shape with hedge clippers or hand pruners, removing old wood. Clipping the tips of hedge branches encourages dense blossom set.
Prune out some inner branches at the base to promote new growth for a thicker hedge. Use hand pruners to reach interior branches.
Clip an Arabian lilac hedge in mid-summer for a burst of flowers from late summer until frost.
Train a young Arabian lilac shrub as an upright tree. Select a central upright branch to use as a trunk, and prune away branches that are close to the ground. Stake the upright, if necessary, to coax it into shape.
Allow branches to develop near the top of the central upright, pruning the tips to encourage new growth. Keep lower lateral branches trimmed off to maintain a trunk-like appearance.
Maintain the tree form during annual pruning. Encourage blossoms and foliage by pruning back the upper lateral branches to the shape you desire.
The cut stems and crushed leaves of Arabian lilac exude a pleasant, spicy scent. Use clippings in wreaths or bouquets for fragrance, or add crushed leaves to dried potpourri.
Clean pruners with rubbing alcohol before and after use to prevent spreading disease among plants. Termites are sometimes attracted to Arabian lilac. Gather dead branches and plant litter and dispose of them.