Stool this shrub, Caryopteris incana, back to a few buds in April just as growth begins and the reward at this time of year are arching shoots covered in a mass of flower at the leaf axils.
C. incana a native to Temperate Asia (China, Japan, Korea) has aromatic grey leaves. It appreciates a warm sunny corner with the roots delving down into an open well drained soil. Through severe winters a degree of protection will be required from deep cold conditions.
Depending on the shade of blue you favour many cultivars are available. A cultivar with pendulous form has also been commercialised.