Spiraea thunbergii

Thunberg Spirea

Rosaceae

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Habitat

  • native to Japan and China
  • zone 4

Habit and Form

  • a deciduous vase-shaped shrub
  • 3' to 5' tall with an equal width
  • dense shrub with numerous branches
  • predominately branches from the base
  • medium growth rate
  • fine texture

Summer Foliage

  • alternate leaf arrangement
  • thin, linear leaves
  • 1" to 1.5" long and only 0.25" wide
  • fine serrated leaf margins
  • extremely short petiole
  • pale green leaf color

Autumn Foliage

  • yellow-orange fall color
  • leafs hold late
  • somewhat showy

Flowers

  • white
  • 0.33" diameter, 3 to 5 flowered umbel
  • flowers in spring, before leafs out
  • first spirea to bloom

Fruit

  • brown follicle
  • hold through winter
  • not ornamentally significant

Bark

  • stems are extremely fine and slender
  • zigzag pattern
  • light brown in color
  • downy to glabrous

Culture

  • full sun to light shade
  • prefers well-drained soil
  • transplant from container for best results
  • soil tolerant
  • does not like wet sites
  • requires pruning to keep in good condition

Landscape Use

  • for early flowers
  • group or mass plantings
  • for border
  • for foundation plant
  • for leaf color
  • for open airy growth habit

Liabilities

  • suckers
  • fireblight
  • leaf spot
  • powdery mildew
  • unkept appearance if not pruned

ID Features

  • white flowers before leaf out in Spring
  • brown follicles that is held through winter
  • zigzag stem pattern
  • buds held at 45 degree angle from stems
  • willow-like leaves, serrated
  • alternate leaf arrangement
  • loosely spreading habit

Propagation

  • by softwood cuttings
  • by seed

Cultivars/Varieties

Spiraea x arguta - The "Garland Spirea", this is a hybrid with S. multiflora that appears similar in most respects to S. thunbergii. It may grow larger and bloom slightly later. 'Compacta' forms a compact mound 5' tall and 3' wide that is covered with white blooms in early spring. 'Graciosa' may be a form with an improved show of white flowers in early spring.

Cultivars of S. thunbergii include:

'Fujino Pink' - This selection is similar to the species in all respects save the flowers, which show light pink coloring.

'Mt. Fuji' - A new variegated form, this rather attractive 4' tall shrub offers white striped narrow leaves and typical white spring blooms. Some of the leaves are also twisted and curled, for added interest to this fine-textured shrub.

'Ogon' (Mellow Yellow®) - This plant is becoming more popular for its wispy branches that are covered with small yellow leaves in spring. The coloring seems to dull to green during the summer. It flowers like the species.

'Yat Sabusa' - A cultivar with double white flowers, this form is rarely seen and appears identical to the species in other respects.

© Copyright Mark H. Brand, 1997-2015.

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Citation and Acknowledgements: University of Connecticut Plant Database, http://hort.uconn.edu/plants, Mark H. Brand, Department of Plant Science and Landscape Architecture, Storrs, CT 06269-4067 USA.