Thunberg spirea is one of the earliest blooming shrubs in the Spiraea genus. The small white flowers appear before the leaves on arching branches in April.

The genus Spiraea consists of small to medium sized flowering shrubs with a fine-textured twiggy mounding habit. The small simple leaves are generally lance-shaped and held close to the branch. Spring to early summer abundant blooms tend to be in white or pink tones, depending on the species and/or cultivar. While individual flowers are quite small, they occur in clusters of inflorescence that can be very showy.

Spireas are best used in groupings in a shrub or mixed border, where they are valued as tough, reliable and easy-care performers in northern climates. The Chicago Botanic Garden's collection includes nearly 100 varieties and 3,000 plants.