Chaste Tree

The chaste tree (Vitex agnus-castus) is a large shrub or small tree with fragrant leaves and long spikes of purple-blue flowers that bees and butterflies love. It is also known as vitex, chasteberry, monk’s pepper, and Abraham’s balm, and it has been grown in gardens and used in traditional herbal medicine for thousands of years.

Scientific Classification & Quick Facts

Common name	Chaste tree
Scientific name	Vitex agnus-castus
Kingdom	Plantae
Phylum	Tracheophyta
Class	Magnoliopsida
Order	Lamiales
Family	Lamiaceae
Genus	Vitex
Conservation status	Data Deficient
Type	Deciduous shrub or small tree
Habitat	Full sun and well-drained soil
Native range	Mediterranean region, southern Europe and central Asia
Colours	White, pink-lilac to dark blue flowers
Flowering season	June to September
Height	8 to 20 feet
Special feature	Attracts bees and butterflies; sage-scented leaves

Where Does the Chaste Tree Come From?

The chaste tree is native to the Mediterranean region and parts of western and central Asia. It belongs to a large genus, Vitex, whose members mostly grow in tropical and subtropical places. The chaste tree is one of the few kinds that can grow in cooler, temperate climates.

It has been grown in North American gardens since the late 1600s. In the warm southern United States it became so at home that it now grows wild in some areas. Many gardeners there plant it as a summer-flowering substitute for lilac, which does not like hot summers.

What Does It Look Like?

The leaves are shaped like an open hand. Each leaf is split into five to seven narrow leaflets, a pattern called palmate. When you crush a leaf it gives off a strong scent a bit like sage.

In warm climates the chaste tree usually grows 10 to 20 feet (3 to 6 m) tall and about as wide. It often has several trunks and grows into a vase shape that spreads out with age. In colder places it stays shrub-sized.

From early summer to early fall, it produces upright spikes of tiny, sweet-smelling flowers at the ends of its branches. The spikes can be 4 to 12 inches long. Most are lavender to blue-violet, but there are also white and pink varieties, so the colors can look a lot like lilac.

Photo by: H. Zell

After the flowers fade, the plant forms small, hard, dark fruits about the size of a peppercorn. That is where the name “monk’s pepper” comes from.

A Friend to Pollinators

Chaste trees are covered in bees and butterflies when in bloom, and beekeepers value them as a source of nectar for honey. Their summer display of fragrant spikes looks similar to lavender and arrives when many other shrubs have finished flowering.

Growing a Chaste Tree at Home

Sun and Soil

Plant your chaste tree in full sun. It will survive light shade but flowers much less. It needs well-drained soil and does not like wet feet, so avoid low spots where water collects. It handles sandy, rocky, acidic, or alkaline soils, but very rich, soggy soil can lead to root rot.

Climate

The chaste tree loves heat. It is generally hardy in USDA zones 6 or 7 through 9. In colder areas it may die back to the ground in winter, but it usually sprouts again from the roots in spring and still flowers the same year, because it blooms on new growth. Plant it in spring after the danger of frost has passed.

Watering

Water young plants regularly during their first season. Once established, the chaste tree is quite drought tolerant and usually only needs water during long dry spells. A gravel or stone mulch helps the soil dry out between rains.

Pruning and Care

Prune in late winter or early spring, before new growth starts. You can train it as a small tree with one trunk or let it grow as a multi-stemmed shrub. Cutting off faded flower spikes before seeds form often encourages a second round of flowers later in the summer.

Chaste trees usually need little fertilizer. A light feeding in spring is plenty; too much makes lots of leaves and fewer flowers.

Pests and Problems

This is a tough, low-maintenance plant. Root rot in poorly drained soil and leaf spots are the most common problems. Occasionally scale insects, whiteflies, or aphids show up, but they rarely do serious harm.

Harvesting the Berries

The berries ripen in fall, turning dark purple to nearly black. To collect them, rub the ripe clusters gently so the berries fall off the stems, then dry them in a warm, airy spot.

Traditional Uses

The chaste tree has a long history in herbal medicine. Ancient Greek and Roman writers, including Hippocrates, Theophrastus, Dioscorides, and Pliny the Elder, mentioned it. The Latin name agnus-castus means “chaste lamb,” and according to legend, monks in the Middle Ages chewed the seeds, which is another reason it is called monk’s pepper.

Today, chasteberry supplements are traditionally used by some women for monthly cycle problems such as PMS. Scientists think it may affect certain hormones, and some studies suggest it can help with PMS symptoms, but more research is needed.

Chasteberry is not right for everyone. It can interact with hormone medicines and birth control, and it is not recommended during pregnancy or breastfeeding. Reported side effects are usually mild, such as upset stomach, headache, itching, or acne. Anyone thinking of taking it should talk to a doctor first.

Chaste tree FAQs