Vitex agnus-castus Chicagoland Blues - Chaste Tree

Vitex agnus-castus 'Chicagoland Blues' is a variety of hybrid Chaste Tree that is appealing for its modest growth and well suited for small gardens. This broad and bushy shrub has many other advantages: generous summer flowering with long spikes of beautiful deep lavender-blue flowers, very dark stems, aromatic grey-green foliage, good cold resistance, and excellent drought tolerance. The list of its qualities would be incomplete if we did not mention that it does not self-sow, that it tolerates sea spray perfectly, and adapts to salty, sandy, poor, or even limestone soils. Objectively, few plants can rival this wonderful Vitex.

Vitex 'Chicagoland Blues' (also known as Daniel Searle) is an American horticultural creation resulting from the cross-breeding of two botanical species: itex agnus-castus, native to the Mediterranean basin and Asia Minor, and V. rotundifolia, widespread along the Pacific coast. Vitex is often criticised for its excessive growth, disorderly habit, and somewhat weak flowering. All these flaws are corrected with this new compact and very floriferous variety. Vitex belongs to the Verbenaceae family.

'Chicagoland Blues' has a broadly rounded, very dense habit with dark branches that stand gracefully. Once mature, it will measure about 1.5 m (5 ft) in height and 1.8 m (6 ft) in spread. Its flowering takes place in August-September, on the current year's shoots. Long, upright spikes cover the plant, adorned with tiny flowers of a rather dark lavender-blue. These flowers do not produce viable seeds, but they attract many pollinators. The fast-growing stems are strong, flexible and almost black. They develop rounded leaves quite late in spring. Their colour is a dark greenish-grey, matte, and slightly silvery on the underside. The foliage emits a peppery scent when crushed. Vitex has a very deep root system, which allows it to draw moisture when the summer is dry. In very cold regions, the above-ground parts of the shrub will be destroyed, without harmful consequences for the plant, which will regenerate its vegetation in a few months and flower abundantly on its new shoots. The deciduous foliage falls in autumn.

Often found by the sea, sometimes very close to the shore and anchored in the sand between rocks, Vitex agnus-castus withstands drought once it is well established, much like the tamarisks with which it gets along well. Having retained the qualities of this undemanding and robust shrub, the hybrid 'Chicagoland Blues' variety proves more decorative and easier to use in the garden, even when space is limited. Its modest growth allows it to easily integrate into shrub borders. For example, associate it with oleanders (in mild climates), buddleias, or even summer tamarisks. This shrub, with its giant blue lupin-like appearance, is superb surrounded by yellow daylilies, shrubby St. John's worts, or grasses like Miscanthus sinensis 'Yaku jima'. If your climate allows, you can also combine it with a purple-leaved Pittosporum Tom Thumb.