Novice and experienced gardeners alike love spirea bushes (Spiraea) for their eye-catching beauty, fast growth rate, hardiness and ease of care. Spirea shrubs are deciduous shrubs that can be divided into two categories: spring blooming and summer blooming. The spring blooming spirea has a delicate cascading habit with large clusters of white flowers poised on arching branches. The summer blooming spirea bush boasts beautiful pink, white or red flowers atop upright branches. Both varieties are prized for their shape and flowers.