Chaste Tree is an old-fashioned Southern favorite, but this improved cultivar produces larger, longer-lasting, more fragrant blue flower panicles than many of its predecessors. Savvy gardeners plant Shoal Creek toward the rear of the perennial border, where it provides the perfect backdrop to summer-flowering daylilies, coneflowers and other mid-size plants. In the heat of the summer, the refreshing cool blue flowers and aromatic gray-green foliage soothe the spirit as well as the senses. Where you grow Chaste Tree will depend on your location as it's typically a tall herbaceous perennial (3-5' tall) in the North (Zones 5 and 6), but is a large shrub (10-15' tall) or sometimes even a small tree in Southern gardens (Zones 7-9). It tolerates heat and humidity better than many plants, and by blooming late in the season when other flowers have faded, it provides color when we need it the most. Vitex agnus-castus 'Shoal Creek'