Vitex negundo aka Chinese Chastetree

Vitex negundo, or chaste tree, belongs to the mint family. Its native range spans eastern Africa and the western Indian Ocean. It also reaches from Iran to Japan and the Marianas. This deciduous shrub can form a small tree with several trunks. Wild plants grow in rough ground and on mountain slopes. Useful Tropical Plants reports its conservation status as Least Concern.

Garden plants reach 10–15 feet [3–4.6 metres] in warm climates. Their spread reaches 6–10 feet [1.8–3 metres]. Some plants grow taller, reaching about 26 feet [8 metres]. Cold winters can limit growth to 3–5 feet [0.9–1.5 metres]. Loose branches form an open, vase-like crown. The bark has red-brown tones. Slender twigs have four sides and grow in opposite pairs. The gray-green leaves also grow in opposite pairs. Each palmate leaf has three to seven narrow leaflets. Thick, woolly hairs cover their lower sides.

Small, scented flowers open on new shoots during summer. Missouri Botanical Garden gives the bloom season as July to August. The blooms range from blue-purple to lilac and lavender. They form loose panicles at the ends of shoots. Each tubular flower has lobes of unequal length. Fine hairs cover its floral parts. Butterflies visit the flowers, and insects pollinate them. The fleshy fruit is a round or egg-shaped drupe. It turns purple or black as it ripens.

Give this plant full sun and loose soil that drains well. It prefers moist soil and grows in sand or loam. It accepts acid, neutral, and alkaline soils. Sources list USDA zones 6–9, but zone 6 brings winter risk. Severe cold can kill the stems down to ground level. A sheltered site helps in colder gardens. Gardeners can cut stems back in early spring. Removing spent flowers can help extend the bloom season. Serious pest and disease troubles are uncommon. Leaf spot and root rot can affect stressed plants.

The foliage and summer flowers suit borders, hedges, and butterfly gardens. Young stems supply material for baskets and woven work. People also use the plant to help hold slopes. Its leaves have traditional uses for repelling insects. Several plant parts have a history of medicinal use. Seeds serve as a pepper-like spice. Washed, ground seeds have served as flour during food shortages. People make tea from the roots and leaves. PFAF and Useful Tropical Plants report no known hazards. That does not establish safety for every use.