Scientific: Vitex agnus-castus
Common: lilac chaste tree, chasteberry, Monk's pepper tree
Family: Verbenaceae
Origin: Southern Europe, naturalized in the southeastern United States and seed will germinate readily in irrigated Phoenix landscapes.

Pronounciation: VI-tex AG-nus CAS-tus

Hardiness zones:
Sunset 4-24
USDA 6-11

Landscape Use: Lilac chaste tree makes a nice large background shrub, to small multiple trunk shade tree for residential and commercial landscapes; use for mesic or oasis landscape design themes, unique summer flowing accent tree or shrub.

Form & Character: Winter deciduous habit, upright, arching and spreading.

Growth Habit: Moderately fast to 20 feet with equal spread. Growth rate and floral display related to moisture availability.

Foliage/texture: Slightly pubescent, dull green, classically palmately compound leaf, 5 to 7 lanceolate leaflets to 6 inches long; medium texture in summer.

Flowers & fruits: Terminal plumes/spikes of white to violet blue (most common)flower plumes to 3 inches long, attract bees; fruits are small brown seed capsules on stalks, unsightly, persistent through the winter months.

Seasonal color: Lilac chaste tree produces copious and intense plumes of blue flowers in early summer (that would be late May to June in Phoenix). During late winter, lilac chaste tree leaves turn a golden yellow color, though the intensity of fall color varies from year-to-year in Phoenix.

Temperature: Lilac chaste tree needs summer heat for best flowering, and because of this it's no surprise that it flowers like crazy in Phoenix in May.

Light: Full sun

Soil: Tolerant of alkaline soil.

Watering: Apply regular, deep. but infrequent water from April to October. Little to no supplemental water is needed during the rest of the year. Like bougainvillea, more water = faster growth, but fewer flowers.

Pruning: Vitex can be trained many different ways ranging from elevating the canopy base into a small tree to heading it back severely to any desired height. Best to prune while dormant from December to early March.

Propagation: Seed

Disease and pests: Aphids, scale, and white flies

Additional comments: In Phoenix, lilac chaste tree is a great large shrub or small multiple trunk tree for an early summer (May-June) floral display. Some clients may not like this plant because it is deciduous (sticks and seeds during winter!). Vitex has a long history of medicinal value. Herbal use for treatment of amenorrhea.

There are many outstanding cultivars including: