The Japanese spirea (Spiraea japonica) grows in the mountains of Japan with medium green leaves and pale pink flower clusters that are in bloom from May to August. The cultivar Gold Mound displays light golden yellow leaves, which adds contrasting foliage color to a mixed shrub border or foundation planting. A deciduous shrub, the Gold Mound spirea grows well in U.S. Department of Agriculture plant hardiness zones 4 through 8.
While definitely having Japanese spirea lineage, the Gold Mound cultivar arose in a garden setting. It's a chance seedling resulting from the cross between cultivars Alpina and Goldflame. Historically, the parentage was listed as S. japonica var. alpina and S. x bumalda Goldflame, according to the Missouri Botanical Garden. Horticulturists maintain the unique genetics of Gold Mound through vegetative propagation of cuttings.
The Gold Mound Japanese spirea naturally develops an upright mounded to oval silhouette. Many thin branches emanate from the roots, creating a mature plant of roughly 2 to 3 feet tall and 3 to 4 feet wide. The flowers form on current growth -- the twigs and stems that have grown since the start of spring. Therefore, any trimming or harsh, rejuvenation pruning should be done in late winter so new growth produce flowers by midsummer.
The small, tapering oval leaves of Japanese spirea range from 1 to 3 inches long and display sharply serrated edges. In spring, the emerging leaves of Gold Mound look bright golden yellow and slowly mature to more yellow-gold. American woody plant expert Michael Dirr comments that the golden foliage of Gold Mound tends to stay more yellow even in the hottest days of summer. By contrast, its parent, Goldflame, fades its leaves to more green-yellow when it gets hot. Depending on climate, pink flowers grow in wide, billowy clusters from branch tips in late spring to midsummer. The tiny blossoms attract bees and butterflies. A lightly trimming of the branch tips after the flowers wane often results in another flush of flowers a month later. In autumn, the foliage turns orange-salmon.
Growing Gold Mound Spirea
Gold Mound spirea prospers in any fertile garden soil that is moist but well-drained. Siting it in full sun produces the most compact habit as well as the heaviest production of flowers. In hot summer areas or where irrigation isn't available, partial sun proves better as it prevents leaf scald and reduces the plant's water needs. Pests rarely become worrisome on healthy spirea plants, but leaf spot, fire blight, powdery mildew, root rot, aphids, leaf roller and scale can affect spirea.
- Missouri Botanical Garden: Spiraea Japonica Gold Mound
- "The Random House Book of Shrubs"; Roger Phillips and Martyn Rix; 1989
- "Dirr's Hardy Trees and Shrubs"; Michael A. Dirr; 1997
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