Spirea Size: How Big Do Spirea Bushes Get?
The final size of a spirea bush is determined by its specific variety, its growing conditions, and ongoing care, ensuring it fits your space.
Spirea shrubs are a popular choice in landscaping for their resilience, attractive foliage, and plentiful clusters of flowers. These deciduous shrubs are hardy and adaptable, making them suitable for a wide range of garden designs. The considerable diversity within the spirea family means their mature size can differ significantly, a trait that adds to their versatility in landscape planning.
Common Spirea Varieties by Size
Dwarf and Low-Growing Varieties
For smaller spaces, container planting, or low borders, several compact spirea varieties are ideal. The ‘Little Princess’ spirea is a popular choice, reaching a height of 2 to 3 feet and spreading 4 to 5 feet wide, forming a dense mound of light green foliage with pink flower clusters in late spring. Another small cultivar is the Double Play Candy Corn spirea, which stays between 18 and 24 inches tall with a spread of 18 to 30 inches, notable for its colorful foliage that changes from red to yellow. ‘Goldmound’ is also a common dwarf type, growing 2 to 3 feet tall and spreading 3 to 4 feet, valued for its vibrant golden foliage.
Medium-Sized Varieties
Medium-sized spireas fit well as foundation plantings or in mixed shrub borders. The ‘Goldflame’ cultivar grows to a height of 3 to 4 feet with a spread of 4 to 5 feet, recognized for the bronze tinge of its new spring growth. ‘Anthony Waterer’, a variety of Spiraea x bumalda, reaches a similar size and is prized for its rosy-pink summer flowers. For those seeking a graceful, arching form, ‘Snowmound’ grows to about 3 to 4 feet tall and wide, covered in white flowers in the spring.
Large Varieties
When a more substantial shrub is needed for privacy screens or as a focal point, larger spirea varieties are suitable. The Vanhoutte, or Bridal Wreath spirea (Spiraea x vanhouttei), is a large variety known for its vase-like shape and cascading branches covered in white spring blossoms. It can reach a mature size of 5 to 8 feet tall and 6 to 8 feet wide. The ‘Renaissance’ spirea is a more disease-resistant version of the Bridal Wreath, growing to a similar height of 5 to 7 feet.
Factors Affecting Spirea Growth
While a spirea’s genetic makeup determines its potential size, environmental conditions influence if it reaches that potential. Sunlight is a primary factor; spireas in full sun tend to have denser foliage, more flowers, and a stronger structure. Shrubs grown in partial shade may become leggier and more sparse as they stretch for light, which can affect their overall form.
The quality of the soil and availability of water also play a part in a spirea’s development. These shrubs perform best in well-drained soil, as overly wet conditions can lead to root rot while poor, compacted soil can restrict root development. Consistent moisture is important when the shrub is young and establishing its root system. Once established, many spirea varieties are drought-tolerant, but prolonged dry spells can still hinder growth.
Controlling Size with Pruning
Pruning is the most direct method for managing a spirea’s size. The timing of this task depends on the shrub’s blooming habit. For spring-blooming varieties like the Bridal Wreath spirea, it is best to prune them immediately after their flowering cycle is complete. This approach allows the plant the rest of the growing season to develop new wood, which is where the following year’s flower buds will form.
Summer-blooming varieties, such as Spiraea japonica and its cultivars like ‘Goldmound’ and ‘Little Princess’, flower on new growth from the current season. These types should be pruned in late winter or early spring while they are still dormant. This timing encourages the plant to produce vigorous new stems, which will carry that summer’s blooms.