Vanhoutte spirea (Spiraea x vanhouttei), often called bridal wreath spirea, is a popular, hardy, deciduous shrub known for its arching branches that cascade with clusters of white flowers in late spring. Reaching 5-10 feet in height and width, it thrives in full sun, adapts to various soils, and is excellent for borders, screens, or hedges. 
Key Characteristics
Size and Growth Rate: Vanhoutte spirea is a large, fast-to-moderate growing shrub, generally reaching 6-8 feet tall, with some specimens growing up to 10 feet in height and 12 feet in spread.
Appearance: It features a vase-shaped, fountain-like habit with arching branches. The foliage consists of small, bluish-green, serrated leaves that may develop purplish hues in the fall.
Flowers: In April or May, the branches are covered in small (1/3 inch), white, umbel-like flower clusters.
Meaning: The genus name, Spiraea, comes from the Greek word speira, meaning wreath, referring to the showy, arching flower clusters. 
Care and Cultivation
Light: Full sun is best for optimal flowering, though it can tolerate partial shade.
Soil and Moisture: It is highly adaptable to various soil types (clay, sand, loam) and is drought-tolerant once established, though it prefers well-drained, moist soil.
Pruning: Prune immediately after flowering in spring to maintain shape and encourage blooming on new growth for the next season.
Hardiness: It is very hardy, generally in Zones 3-8.