The fragrant, light purple blooms of the chaste tree (Vitex agnus-castus) are a beautiful accent in the summer landscape. This fast-growing, tough plant does well in xeric gardens, but it’s also excellent in wildlife-friendly gardens because it attracts butterflies and hummingbirds. Blooms on newer cultivars have scented pink, lilac, or white flower spikes 8 to 12 inches long, and have more fragrance and color than the species. The chaste tree, which has aromatic gray-green foliage, can be pruned to form a tall shrub or small tree.
Common name: Chaste tree, monk’s pepper, sage tree, Mexican lavender
Botanical name: Vitex agnus-castus
Plant type: Deciduous shrub
Height: 6 to 25 feet tall
Zones: 6 to 9
Family: Verbenaceae (Vervain)
- Sun: Full sun
- Soil: Loose, well-drained soil
- Moisture: High drought tolerance once established
- Mulch: Add a thin layer of organic mulch to deter weeds and retain moisture until plants are established.
- Fertilizer: Apply a general-purpose fertilizer in spring before new growth appears.
- Pruning: To improve their shape, trim shrubs’ stems before flower buds form in spring. To renovate old and misshapen shrubs, cut down all stems to within two or three buds of the base in late winter or early spring. To keep shrub smaller (4 to 7 feet tall), cut stems to the base every year in late winter.
- ‘Colonial Blue’ has blue flowers and grows 3 to 15 feet tall. Zones 6 to 8.
- ‘Montrose Purple’ has 8- to 12-inch, lavender-blue spikes and grows 10 to 15 feet tall. Zones 6 to 9.
- ‘Salinas Pink’ has light pink spikes 8 to 12 inches long. Grows 6 to 25 feet tall. Zones 6 to 9.
- ‘Shoal Creek’ has small, fragrant lilac-colored flowers. Grows 4 to 15 feet tall. Zones 6 to 9.
- ‘Silver Spire’ has white flowers and grows 6 to 25 feet tall. Hardy in Zones 6 to 9.
- Use in a shrub border or as a single specimen.
- Leaves and flowers can be messy, so keep away from patios or walkways.
- Prune spent spikes after the first flowering to encourage additional flowering the same season. Remove seed pods as soon as the petals drop and before they harden—the second set of blooms will appear faster if you don’t delay removing them.
- In excellent soils and with no pruning, the chaste tree will grow 25 feet tall. Pruned to the ground every season (treated like a perennial), it will reach 4 to 7 feet tall.
- In southern climates where lilacs don’t do well, use the chaste tree as a substitute.
- If planted where soil is too wet, root rot can develop.
- Leaf spots and scale sometimes occur.
- Take semi-ripe cuttings in summer.
- Layer lower limbs in summer.
All in the family
- Beautyberry (Callicarpa spp.), Caryopteris, shrub verbena (Lantana spp.), Verbena bonariensis, and rose vervain (V. Canadensis) are some of the better-known plants in the Verbenaceae family.
Text by Mary Pestel, photo courtesy of Monrovia Growers, www.monrovia.com.