Tips for Growing Spiraea
Common name: none
These popular, quick-growing deciduous shrubs fall into two groups – the spring and the summer. They are particularly noted for their free-flowering habit.
Popular species and varieties
The best known form for spring flowering is the bridal wreath (Spiraea ‘Arguta’). The slender arching branches are completely covered with clusters of pure white in mid-spring, and the shrub will grow to around 2m (6ft). It is no stranger to our gardens having been grown for well over a hundred years. Also flowering in spring, and noted for its plentiful blooms, is Spiraea ‘Grefsheim’ (AGM).
The summer-flowering group is dominated by varieties of Spiraea japonica. Probably the best known is ‘Anthony Waterer’ (AGM), which grows to 1m (3ft). The foliage is tinged with pink and cream, and it carries pink flowers for several weeks from early summer ‘Goldflame’ (AGM), with rose-red flowers, is another good choice. The leaves, when young, are a reddish-orange, changing to gold and eventually green. ‘Fire Light’ is worth searching for — its young, bright orange-red foliage changes to orange-yellow and eventually pale green, before taking on a fiery red in the autumn, Finally, the dwarf ‘Gold Mound’ (AGM) grows to just 30cm (12in), with small heads of pink flowers from mid-summer.
Soil type Most fertile, well-drained soils are suitable.
Planting Spiraea is happy in full sun or lightly shaded positions. Plant wheneverconditions are suitable from early autumn to late winter.
Pruning Those that flower in the spring only require old and weak growth to be cut out after flowering has finished. The summer-blooming group should be cut back in early spring to within 7-10cm (3-4in) of the ground.
Propagation Take semi-ripe cuttings in summer, or hardwood cuttings with a heel in autumn.
Pests and diseases One pest that can strip foliage is the larvae of sawflies. These can be controlled by using a contact insecticide as soon as they are seen.