Purple smoke bush is often used as a garden specimen due to the purple-pink plumes and the purple leaves on some cultivars. It is highly drought tolerant. Common Names: Purple smoke bush, smokebush, smoketree, purple smoke tree. Zones 4-9. Size & Shape: Purple smoke bush grows to a size of 12-15' tall and wide. It is irregular to rounded. Exposure: Grow purple smoke bush in full sun.