About 90 different species belong to the plant genus Spiraea. These are shrubs that throw off leaves. The genus Spiraea belongs to the large Rosaceae family and is native to the temperate climate zones of the northern hemisphere. There are about 70 species in China alone. There are a number of attractive flowering shrubs among them, which are also hardy in our latitudes and versatile in the garden.
Appearance and growth
spirea or Spiraea grows densely branched and compact, depending on the species tightly upright or funnel-shaped with overhanging twigs. The varieties of the Japanese spar (Spiraea japonica) grow as hemispherical dwarf shrubs that grow to only about 50 to 100 centimeters in height. Other species such as the bridal pier (Spiraea x arguta) or the magnificent pier (Spiraea x vanhouttei) can reach a height of two metres, and pier shrubs are found early in the year. The leaves of the spirea are simple and mostly short stalked. They sit alternately at the branches and are often sawed, toothed or also lobed at the edge. In addition to the pure green-leaved spar, there are also varieties with yellow-green foliage such as ‘Golden Princess’, some also have a beautiful autumn colour.
spirea or Spiraea’s flowering is luxuriant because the inflorescences are very densely distributed over the whole of last year’s shoot. The flowers stand in panicles, umbrella panicles or umbels on the shoots. The small, round individual flowers have five sepals and five petals and are mostly white, rarely pink. They carry 15 to 60 stamens. Depending on the species, it blooms in spring from April or in summer from June. Small bellows fruits develop, which are frequently twisted. The name of the plant also refers to this. Spiere comes from Greek: “speira” means “winch, winding”.
Location and soil
Sparns like a sunny to slightly shady location with moist, permeable and nutrient-rich soil. Important to know: The sunnier the location, the more luxuriant the flower. The plants do not tolerate too much lime in the soil and dryness well.
The robust spar shrubs can be planted all year round as container goods, although – as with many other ornamental shrubs – autumn is considered the best planting season. Pick out a planting hole that is at least twice the size of the root ball and loosen the sole in the planting hole slightly. In heavy soils, a thin layer of gravel at the bottom of the planting hole improves water permeability. After planting, press the soil down well and water it thoroughly. A mulch layer ensures that the moisture does not evaporate so quickly.
They are easy to care for at a suitable location. They should be watered regularly in the first year after planting. Mulching the planting areas also helps to maintain moisture in the soil.
Summer bloomers such as the Japanese spirea are cut back strongly in early spring. This promotes vigorous new shoots and lush flowering in summer. In spring, flowering spar shrubs such as the bridal spar should be thinned out every two to three years after flowering. This means that all older shoots, but not more than one third of all shoots, are cut off at the base so that the plant tapers regularly.
Wintering or winter protection
spirea or Spiraea is winter hardy in our latitudes and does not need any extra winter protection.
spirea trees can be used in many different ways in the garden and, due to their compact growth, are also well suited for smaller gardens. The higher, shrub-like spires are well suited for free-growing flower hedges. The low, spherical spar shrubs can be planted in small groups in conjunction with ornamental grasses and shrubs or as low hedges. They can also be used over large areas as ground cover or as permanent planting for tubs. If you want to use flowering twigs for the vase, you should cut them already fully flowered.
Important species and varieties
spirea or Spiraea are among the most widespread ornamental shrubs in our gardens – no wonder, since they are undemanding, robust and blooming in abundance. The genus Spiraea can be roughly divided into two groups: the early flowering species, which already show their flowering splendour in April/May, and the summer flowering species, which flower from June to September. Spring flowers include, for example, the bridal spar (Spiraea x arguta), the ash-grey spar shrub (Spiraea x cinerea) and the magnificent spar (Spiraea x vanhouttei). Later in the year, the Japanese spar shrub (Spiraea japonica) and the ‘Anthony Waterer’ variety (Spiraea x bumalda), which is particularly popular among gardeners, bloom. This variety, also known as red summer pier, is a hybrid of Spiraea albiflora and Spiraea japonica and has ruby red flowers during the summer months. With a growth height of only 60 to 80 centimeters, it is well suited for low flower hedges. The flowers are also strongly approached by insects.
spirea or Spiraea can be well propagated in spring by cuttings. One uses for this about 15 centimeters long, half timbered shoots. Also the propagation by lowering is possible. In autumn, you can also multiply your spar shrub with wood.
Diseases and pests
The robust spar shrubs are insensitive to diseases and pests.