Last year I received a gift shrub from a dear friend. The tag said “Blue Mist Spirea.” There was no Latin name included. When I did a little research online to learn the plant’s sun and water requirements, I was astonished to learn that it was NOT a Spirea. Not even close. Instead, this gray-leaf beauty with clusters of tiny powder-blue blooms is a Caryopteris. So why call a Caryopteris a Spirea? Beats me. They are not even in the same family. I can only guess that there was some confusion in the plant breeder’s greenhouse and once the patent was received or the plant tags were printed, it was too hard or expensive to make the correction.
Many garden centers will offer “Blue Mist Spirea,” but you may also find ‘Longwood Blue,’ ‘Beyond Midnight,’ ‘Dark Knight’ and ‘Grand Bleu.’ The ‘Worchester Gold’ cultivar has some yellow to its foliage, but it is not as golden as the name might lead one to believe. It tends to turn more green where summers are hot.
Plant Caryopteris in full sun, in well-drained, lean soil. Too rich a soil produces soft growth that is weak and floppy. It is heat and drought tolerant. The blooms attract numerous butterflies and bees, so site them away from busy pathways and entrances. The shrub naturally forms a nice mounded shape with a fine texture. It is deciduous, losing every leaf when hard freezes arrive. The branches should be pruned hard (down to 12 inches or less) in early spring because blooms occur only on new growth. Pruning will also keep the plant dense and compact. Resist the temptation to trim until spring arrives and new growth starts to show. If you prune in autumn or early winter, the plant may not live through cold weather. Wet soil in winter may also cause plant death.
Caryopteris are easy to grow from cuttings, but many times the plant self-propagates by growing roots wherever a branch touches soil. These rooted branches can be separated from the mother in spring and transplanted to new locations. Caryopteris look pretty when paired with gray-leafed Artemesia such as ‘Powis Castle’ or contrast nicely with burgundy foliage. It also looks fabulous planted next to orange Zinnias.
Caryopteris foliage has a distinctive odor that deer don’t like. Some people describe it as smelling like bell pepper. I don’t agree, but cannot find another comparison that is more accurate. Deer do not browse it and insects do not bother it. This small scale (36 inches or less) shrub is trouble free and should be planted more often. It is hardy in Zones 6-9.