(Credit: Pixabay)

As planting season approaches, gardeners everywhere are contemplating ways to improve their landscapes. Spirea is a remarkably versatile, low-maintenance shrub prized for its graceful, arching, or compact forms, providing stunning, multi-season interest with vibrant foliage and delicate flowers. Once considered a bit common, spirea has been improved in recent years and now includes cultivars that offer dramatic spring, summer, or fall color. In short, it has become a workhorse shrub in modern landscapes.

Bridal wreath spirea is the shrub most people associate with the genus Spirea and gets its common name from the small clusters of white flowers spaced on gracefully arching branches. (Credit: Pixabay)

The genus name Spirea originates from the Greek word speira, or "wreath," which makes reference to the orientation of the shrub's delicate flowers. With nearly 100 species, this hardy genus of plants boasts a wide range of colorful foliage ranging from blue to yellow, red to orange, and nearly everything in between. Although native to Japan, China, and Korea, they have become American heartland landscape plants.

Common species and hybrids of this long-time garden favorites include:

• Japanese spirea (Spiraea japonica) is known for its wide flower and foliage color range, and its low-growing and mounding form.
  
  

  Along with its attractive flowers, Japanese spirea is noted for its colorful foliage. Pictured is the cultivar ‘Goldmound’. (Credit: North Carolina State University)

  
  
• Bumalda spirea (Spiraea x bumalda) is similar to Japanese spirea but is a cross between S. albiflora and S. japonica. Flower color ranges from white to deep pink.
• Birchleaf spirea (Spiraea betulifolia) is known for its larger, blue-green, birch-like leaves and stunning fall color.
  
  

  Birchleaf spirea displays spectacular fall leaf color. (Credit: National Garden Bureau)

  
  
• Korean spirea (Spiraea fritschiana) is native to forests, slopes, and rocky areas and, like most spirea, attractive to butterflies. It is noted for its dark green foliage and large, white flower clusters that appear in late spring.
• Vanhoutte spirea, or bridal wreath, (Spiraea x vanhouttei) has been a landscape favorite for many years. It is known for its vase-shaped habit, flowing, arching branches, and cascading showy spring blooms.

Although the preceding species and hybrids still are widely planted, new cultivars are available that add versatility to this useful shrub in home landscapes and gardens. The following represent a few notable examples:

• Tor Birchleaf – 'Tor' produces a compact mound of dark, gray-green, birch-like leaves that sport tiny white flowers in late spring. Like most birchleaf types, it boasts amazing fall color. Height: 3-4'. Width: 3-4'.
• Glow Girl® Birchleaf – A great plant for those who need easy, adaptable color for colder climates, it produces striking lemon-lime foliage. Height: 3-4'. Width: 3-4'.
• Rainbow Fizz™ – Aptly named, this new spirea adds a burst of color to the landscape with candy-like buds that emerge red and open to pink. Height: 3-4'. Width: 3-4'.
• Double Play Candy Corn® –The Double Play® series of spirea are continuous bloomers. 'Candy Corn' makes a great landscape statement with its brilliant foliage that emerges bright red, turns pineapple yellow, and finishes with orange tones. It produces red blooms all summer long. Other Double Play® cultivars include 'Big Bang' and 'Doozie.' Height: 2-3'. Width: 2-3'.
  
  

  With its vibrant foliage and attractive flowers, Double Play Candy Corn® is an example of a spirea cultivar that blooms continuously throughout the growing season. (Credit: Proven Winners)

  
  
• Pink Sparkler™ – This new birchleaf selection produces pink flowers in early summer and then again in autumn. The result is a late show of color after most deciduous shrubs have stopped blooming. Height: 3-4'. Width: 3-4'.
• Superstar® – This new spirea offers three-season appeal thanks to its stunning, scarlet red new growth in spring, its pink blossoms from May to August, and its excellent bronze fall color. Height: 2-3'. Width: 3-4'.

• Firegold® – Spirea 'Firegold' bears brilliant lemon-lime foliage. Otherwise, it resembles the old-fashioned bridal wreath spirea, and arches gracefully while producing lovely white blooms in spring. Height: 4-6'. Spread: 5-7'.
• Little Spark® – This new, compact spirea produces orangish new growth that turns yellow. The yellow leaves are held throughout the summer, even in full sun. Height: 18-24". Width: 18-30".
• Renaissance bridal wreath – While more disease-resistant foliage than other bridal wreath cultivars, 'Renaissance' still produces classic white blooms that cover the plant. It is a selection from Spirea x vanhouttei. Height: 5-7'. Width: 6-8'.
• Goldflame – A selection from Spirea japonica, 'Goldflame' bears bronze-tinged new growth in spring. It produces dark pink flowers on plants with a compact, neat growth habit. Height 3-4'. Spread 4-5'.
• Dolchica – Unique in flower color for a spirea, 'Dolchia' produces graceful dark mounds of purplish flower clusters on purple-red foliage that matures in summer to green. Height 3'. Spread 4'.
• Little Princess – A petite selection from Spirea japonica, 'Little Princess' bears showy flat-topped clusters of bright pink flowers in early summer. Height 2'. Spread 3'.
• Snowmound – 'Snowmound' lives up to its name. It produces an abundance of snow-white flowers on graceful, spreading branches. Height 3-5'. Spread 3-5'.

Even the most compact varieties of spirea establish themselves rapidly, making them ideal choices for quick fill-in plantings, massing, hedges, and foundations.

Spireas are deciduous shrubs and drop their leaves each fall. Cold hardy from USDA Hardiness Zones 4–8, they can tolerate winter temperatures as low as -15 to -30 degrees Fahrenheit. Best grown in full sun, plants located in shadier spots tend to become lanky and do not bloom well. Although they prefer good, well-drained soil, spireas tolerate poor soil, pollution, drought, heat, the afore-mentioned cold temperatures. Once established, they are one of the lowest maintenance, easy-to-grow shrubs available to gardeners. Normally, minimal supplemental watering is needed except during very dry weather. Mulching with shredded bark or wood chips will help retain moisture.

Species in the genus Spirea are renowned for their ability to withstand both cold and hot temperatures, and for being easy to care for. Pictured is the cultivar ‘Anthony Waterer’. (Credit: North Carolina State University)

Routine pruning can be done to plants that grow larger than desired. Since spireas bloom on "old wood" (previous year's growth), it is best to prune after flowering. In addition to heading back, spireas should be thinned from the center to improve air circulation. Unlike some landscape plants, spireas can be pruned hard (reduced by two-thirds) to rejuvenate older, overgrown plants.

In general, spireas are not favored as a food source for wildlife such as deer and rabbits. However, their beautiful blooms attract an abundant show of butterflies, bees, and other pollinators bringing added interest to the landscape.

Acknowledgement: Adapted from an article by the National Garden Bureau.