Spiraea

From a garden standpoint there are two very distinct groups of spiraea, one which makes rounded or shuttlecock-shaped bushes from a compact stool, the other which makes a thicket of erect stems spreading ever wider by suckers. The latter, though excellent in semi-wild places where there is plenty of room, can be a nuisance in small gardens or more formal situations where they must be constantly kept in place by chopping through their tough stolons in winter. All these suckering spiraeas produce their flowers in fluffy bottle-brush spikes in late summer, and the least overpowering and most beautiful of them is Spiraea billiardii triumphans (also known as S. menziesii triumphans), 6 to 8 ft., with rose-pink flowers, but it is not suitable for markedly alkaline chalk or limestone soils.

Spiraea

In the other group there are numerous fine garden shrubs. Spiraea arguta, popularly known as bridal wreath, crowds its thin, twiggy stems with snowy bloom in April and May. It is 5 to 6 ft. high. S. thunbergii is similar, 3 to 4 ft. high, and a week or so earlier. S. bumalda grows 3 ft. high and has flattish heads of rose-pink flowers (crimson in variety Anthony Waterer) all summer. S. prunifolia is 5 or 6 ft. high with arching stems loaded with double white flowers in April and May. S. vanhouttei is similar in habit but has clusters of single flowers in June. S. veitchii is a larger shrub, 8 to 9 ft. high, with white flowers all along the arching stems in June—July. There are many more.

S. x cinerea ‘Grefsheim’ is a compact, bushy shrub up to 1.2 in tall, which flowers profusely in April-May. It has lanceolate, sea-green leaves covered with silky hair on the underside, and pure white flowers; prune immediately after flowering. S. japonica is a broad, upright shrub which flowers from June-August. It has short-stemmed, lanceolate to oval, dark green leaves and pinkish-red clusters of flowers. There are many cultivars, including ‘Albiflora’, up to 50 cm tall, bright green leaves, flowers profusely with terminal clusters of white flowers; ‘Little Princess’, a creeping shrub, 40-60 cm tall, fresh green leaves, flowers profusely with rose-pink blooms; prune back to just above the ground in spring.

English: Spiraea × arguta (S. × multiflora × S...

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S. nipponica, is a vigorous, compact, bushy shrub, 1-2 m tall, which flowers in June. It has reddish-brown stems, oval, dark green leaves which are bluish-green with pale brown veins on the underside, and rounded, white or sometimes pale pink clusters of flowers; ‘June Bride’ is up to 1 m tall and broad, with arching stems and small, white clusters of flowers; also suitable for lime-rich soil.

S. x vanbouttei, bridal wreath, is a vigorous, broad shrub, 1.5-1.8 m tall, which flowers in May-June. It has arching, reddish-brown shoots, rough, oval, dark green, sometimes three-lobed leaves, 2-4 cm long, bluish-green on the underside, and abundant spherical clusters of numerous pure white flowers; after flowering, prune back hard. Grow in groups or as a hedge, in a sunny or slightly shady spot, in fertile soil. Propagate from summer and winter cuttings, and by layering.

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