Snowmound Spiraea
Spiraea nipponica (spy-REE-ah nip-PON-ih-kuh)
Spiraea nipponica, or Snowmound Spiraea, is a drought-tolerant, flowering, deciduous shrub growing rapidly to its full size. For most Spiraea species, the height can range from 5 to 8 feet high and an equal spread; however, Snowmound tends to be a bit smaller with a 2 to 4 foot height. When young it is a slender, slightly arching, shrub, but becomes denser and mounded with age. It grows well in average, medium moisture, well-drained soils in full sun to bring out the best blossoms. However, it will also thrive with light afternoon shade if sited in a place with hot summer climates. It tolerates a wide range of soils, including clay. To extend the flowering and improve the overall appearance of the plant, you should remove faded flower clusters as soon as practicle (light shearing is an option). Keep in mind that Spiraea flower on new wood, so you should prune in late winter or early spring if needed. The plant blooms in late spring, which is later than other white-flowered spiraeas, and produces a frothy shower of clustered, small, white flowers that cover the limbs like a mound of snow. The blue-green leaves are shaped as narrow triangles with an acute angle toward the base. They tend to be narrower than S. x vanhouttei and grow larger than typically advertised for 'Snowmound', making it a good filler plant, as a mass planting, a bank cover, or in front of a shrub border. Flowers and leaves all appear on the same side of the arching branches. Flowers are attractive to butterflies. The plant is seldom damaged by deer. Insects, Diseases, and other Plant Problems: No serious insect or disease problems. Susceptible to many of the diseases and insects that attack other members of the rose family, including leaf spots, fireblight, powdery mildew, rots, aphids, leaf roller and scale.
Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 56 attributes.