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Japanese spiraeas offer late spring pizzazz
By Norman Winter
Central Mississippi Research & Extension Center
Most people think of all spiraeas as the old-fashioned white bridal wreath spiraea, but across the South today, there is another group dazzling spectators called the Japanese spiraeas.
There has been a lot of taxonomic shifting going on in the last few years. Some of the heated arguments have probably taken place over the Spiraea japonica and Spiraea x bumalda and their hybrids, including the most famous variety called Anthony Waterer. There are now 40-45 varieties providing ample opportunity to add some pizzazz to late spring and early summer landscapes, even if no one knows the botanical names.
Whereas the bridal wreath variety has arching stems, the Japanese spiraeas are erect and multi-stemmed, usually 3-4 feet tall. They are deciduous shrubs that produce flat-topped clusters of pink flowers displayed at the top of wiry branches. In the most common forms, the pink color is a mix of light and dark pink, giving a most unique appearance. They bloom most heavily in late spring, then off and on through the summer.
Japanese spiraeas will grow in a variety of soils, including those that are alkaline, but they prefer moist, fertile locations. If you have tight, heavy, compacted clay, add 3-4 inches of organic matter like compost, peat or humus to loosen it.
Dig the planting hole two to three times as wide as the rootball, but no deeper. Widely dug holes open the door to the fastest root expansion and bed establishment.
Moisture is critical the first year, so water deeply when required. Feed four weeks after transplanting with a slow-released, balanced fertilizer like an 8-8-8 or 12-6-6 at 1 pound per 100 square feet of bed space.
Full sun promotes the best blooming, but partial shade seems to work, as well.
From the standpoint of cold hardiness, the Japanese spiraea has a wide range of adaptability from zones 4-8. This means most of the country will treasure the hot pink flowers.
They can be used as small hedges, low screens or foundation shrubs. To make an interesting tropical combination, use them with Bengal Tiger cannas, which provide a real contrast in texture. The lime green of the cannas makes the pink even hotter.
Recently, I came across an exquisite garden where spiraeas were partnered with adjacent Pink Knockout shrub roses. In the foreground of the bed were Homestead Purple verbenas, and a purple clematis was growing on a small trellis behind for a cottage-style garden.
By all means, use them around sitting areas for a splash of color. There are several selections like Limemound, Goldflame and Gold Mound that have lime green to chartreuse gold foliage that makes for a stunning partnership with the hot pink blossoms.
While taxonomists might argue about which goes where, know that the Japanese spiraea is another member of the rose family that offers a lot for the landscape. With so many varieties to choose from, you are sure to find some that will suit your taste -- and the sooner, the better.
Released: May 15, 2008
Contact: Norman Winter, (601) 857-2284
Editor's Note: Ideal publication dates of Southern Gardening columns are within one month of their release. Editors should examine older columns carefully for any information that could be time sensitive.