Delta Blues Vitex ShrubsDelta Blues Vitex Shrubs for Sale Online Delta Blues Vitex (Vitex agnus castus Delta Blues) is a fast growing, large flowering shrub or flowering tree that produces prolific lavender blue flower spikes. The bright blue flowers make a striking contrast to the bright green foliage and their fragrance is irresistible to hummingbirds, butterflies, and pollinators. It has a rounded growth habit, prefers sunlight, and works well as a border planting.