Vitex agnus-castus (Monk's Pepper, Chaste Tree or Chasteberry.)

Botanical Information

FamilyLamiaceae
GenusVitex
Speciesagnus-castus
CategoryWoody
TypeShrub (deciduous)
OriginMediterranean region and Asia.
Pronunciation

Details

USDA Hardiness Zone7-9
USDA Hardiness Ref.
Canadian Hardiness Zone8
Canada Hardiness Ref.
RHS Hardiness ZoneH3-H6
RHS Hardiness Ref.
Temperature (°C)-29
Temperature (°F)-20
Height3-4 m
Spread4-6 m
GrowthFast
Flowering PeriodJune, July, August, September

Description and Growing Information

General DescriptionThe Chaste Tree is a small multi-stemmed deciduous shrub with grey-tan bark. The branches tend to arch slightly over time, creating a full-foliage spread. 'Cannabis sativa-esque' leaves and striking purple flowers make the Chaste Tree a wonderful addition to any urban landscape project.
ID CharacteristicThree prominent features to distinguish the Chaste Tree include the leaflets reminiscent of Cannabis sativa, the long brilliant violet flower spikes, and the round seed capsules which remain through the winter.
LandscapeFrequently used as a specimen, hedge, container, or urban garden plant. Somewhat salt tolerant, so use as a parking lot accent might be worthy.
PropagationPropagation can be accomplished either by direct sowing of seeds or soft wood cuttings. Prepare seeds in freezer for three weeks (stratification), sow when temperatures are between 15°C-21°C. For cuttings, plant in summer.
CultivationPrefers full sun in well-drained soil. Will thrive in acidic to alkaline soils. Tolerant of drought and dry soils. As a half-hardy shrub, it is susceptible to dieback in the winter, but will regrow again from the roots in the spring. It thrives in urban gardens. Annual pruning should be done to encourage proper structural growth. Removing flower stalks before seeds are produced is necessary in order to prevent fewer future blooms.
Notable SpecimensFanshawe College (main campus), London, Ontario, Canada.
HabitatFound along the slightly damp stream edges, despite being drought tolerant.
Bark/Stem DescriptionThe old bark of the Chaste Tree is textured and silvery-tan. New twig growth is green.
Flower/Leaf Bud DescriptionSimilar to the stunning buds of Exochorda x macrantha ‘The Bride’, but longer in form, the light buds are tightly furled, oblong balls that provide a pleasant aesthetic. Colour develops into a slight purple as it nears bloom.
Leaf DescriptionCommonly mistaken for those of the Cannabis sativa plant, the long ovate leaflets are attached by petiolules of five or six to a longer petiole. There is a single lighter green vein running length wise down the middle of the smooth rich green leaves. They are slightly silver underneath, indicating that it is native to a warm climate. The margin of the leaf is entire, unlike the serrate leaves of Cannabis sativa. The leaves are aromatic and stay the same colour into the autumn.
Flower DescriptionThe Chaste Tree is a monoecious plant, meaning it has both male and female flowers on the same plant. The lime coloured calyxes are also attractive with their serrated edges and bell-shape. The lovely spikes of lilac-coloured flowers arrive in late spring through continuing sporadically through early autumn (generally June through September). Delicate white filaments extend from the tubular flowers boasting a purple anther which is very attractive to pollinators, namely honey bees. Other pollinators include butterflies, hummingbirds, and other birds
Fruit DescriptionSmall circular almost black berries develop and turn into brown seed pods that will remain in the winter if not manually pruned off. Seed pods may blow off in the winter with strong winds leaving a mess. In order to keep the plant flowering, flowers must be removed before they go to seed.

Photographs