Chastetree is a non-native shrub or tree which does best in hot weather. In cooler climates, it can be severely pruned to the ground and will usually regrow. It can suffer winter dieback or will die to the ground in USDA Zones 5 and 6; however, the roots often survive and push up several feet of new growth the following year. Pruning can be done in early spring as flowering occurs on new wood. Due to this trait, dieback will not affect flowering. Prune faded flowers to promote continuous flowering. Flowering will be more spectacular if the plant is heavily pruned after blooming.
This tree is resistant to damage by deer and is moderately salt tolerant. It has good drought tolerance once established. It freely reseeds and can become weedy.
In warmer climates, it can be trained to grow as a small, single trunk tree or a large shrub. Although typically grown as a 10-15 foot shrub, in tree form it can reach heights of up to 20 feet. This long-lived specimen’s rapid growth rate can add up to 24 inches per year in height.
Some smaller cultivars like ‘Blue Diddley’ and ‘Blue Puffball’ can be grown as 3 to 6 foot shrubs; other cultivars such as ‘Cooke’s Blue’, ‘Cooke’s Pink’, or ‘Cooke’s Purple’ can grow as tall as 25 to 30 feet with the same spread. There are also many cultivars of various sizes in between.
This plant has the potential to become invasive, especially in southern areas of the country. Its dry fruit can be a litter issue.