Spiraea, often called “Piela” by home gardeners, is a popular and adaptable flowering shrub. It enhances landscapes with its graceful appearance and abundant blooms, offering attractive foliage and a profusion of flowers. Its widespread appeal comes from its relatively easy care and ability to thrive in various garden settings, making it a favored choice for both novice and experienced gardeners.
Understanding Spiraea
Spiraea shrubs are deciduous, shedding their leaves in the fall. They typically range from 1 to 8 feet tall and up to 6 feet wide, depending on the species. The foliage consists of simple, oval-shaped leaves arranged alternately along the stems. Many varieties feature green leaves, while some display chartreuse, gold, or blue-green hues, with some cultivars providing a showy fall display of red, orange, or purple.
The flowers of Spiraea are small and appear in dense clusters. These blooms can be white, pink, red, or mauve, creating a soft, lacy effect. Spiraea varieties are categorized by their bloom time: spring-blooming (May to June) or summer-blooming (July to August). These shrubs are valued for their hardiness, attracting butterflies and other pollinators, and their adaptability to various soil types and urban pollution.
Planting and Basic Care
Spiraea thrives best in full sun, requiring at least six hours of direct sunlight daily for optimal flowering and vibrant foliage color. While spring-blooming varieties can tolerate some partial shade, summer bloomers generally perform better with more sun. These shrubs grow well in average, well-draining soil, but do not tolerate soggy conditions, so good drainage is important.
When planting, dig a hole twice as wide as the root ball and just as deep, ensuring the top is at or slightly above soil level. After planting, water thoroughly to settle the soil. Newly planted Spiraea benefits from consistent watering until established. Established plants are generally drought-tolerant and only need watering when the soil becomes dry. Spiraea shrubs are not heavy feeders; a yearly application of a balanced, slow-release granular fertilizer in early spring is sufficient for optimal growth and bloom production.
Pruning Spiraea
Pruning is important for maintaining Spiraea’s shape, promoting health, and encouraging abundant flowering. The timing depends on whether the Spiraea is a spring-blooming or summer-blooming variety. Spring-blooming Spiraea, such as ‘Bridal Wreath’, produce flowers on old wood. Prune them immediately after their bloom period in late spring or early summer. This allows the plant to produce new growth that will develop flower buds for the following spring.
Summer-blooming Spiraea, including Japanese Spiraea cultivars, flower on new wood. Prune these varieties in late winter or early spring before new growth emerges. This encourages vigorous new shoots that will bear the season’s flowers. Techniques include deadheading spent blooms to encourage rebloom, thinning old or dead branches to improve air circulation, and rejuvenation pruning for overgrown shrubs, which involves cutting the entire plant back significantly in late winter or early spring.
Popular Spiraea Varieties
Many popular Spiraea varieties offer diverse characteristics, suitable for various garden designs. ‘Goldflame’ is a Japanese Spiraea cultivar known for its vibrant foliage, which emerges with red and orange tones in spring, transitioning to a pineapple gold in summer. It produces purple-red flowers from late spring to early summer. ‘Anthony Waterer’ is another Japanese Spiraea cultivar, featuring bluish-green foliage and deep rosy-pink flowers that bloom from late spring into mid-summer. This variety maintains a compact, mounded form.
‘Bridal Wreath’ Spiraea is a classic spring-blooming variety, celebrated for its graceful, arching branches covered in cascades of small white flowers in late April to May. This larger shrub can reach 5 to 8 feet in height and spread. ‘Little Princess’ Spiraea is a compact, dwarf Japanese Spiraea cultivar, typically growing 1 to 2 feet tall and 2 to 3 feet wide. It features mint-green leaves and clusters of pale pink flowers that bloom from late spring through summer, with foliage turning reddish in autumn.