Chastetree (Vitex agnus-castus) is an 8-10 foot deciduous shrub or 12-15 foot tall small tree (hardiness zone 6-b thru 8). Branching habit is dense and vase-shaped (upright). It blooms over most of the summer, from June thru late August. Its 12-18 inch long blue-violet flower spikes exude a slight herbal fragrance.
‘Shoal Creek’ is a leading cultivar. Cold hardiness appears better than most, although this has yet to be proven. The finger-like compound leaves are covered with pubescent hairs. Summer foliage color is grey-green, with a faint bluish cast more visible in May and June. Its disease resistant foliage and butterfly magnetism rates this vitex in a class on its own. Foliage is highly deer resistant.
Stem die-back may occur in a cold winter, but this fast grower recovers rapidly. Since flowering occurs on new growth, prune off all dead, injured and crowded branches before the start of May. Vitex prefers full sun, but will tolerate part sun. Plant in a loose, well-drained soil and keep adequately watered during the first year. Afterwards, vitex possesses very good drought tolerance.