Spirea
01 June 2005

What have spiraea, apples, hawthorn, firethorn and roses all got in common? Amazingly they are all part of the Rocaceae family.

In the middle of the last century these versatile, deciduous shrubs were to be seen growing in every garden. They were easy to propagate from cuttings, untroubled by pests or disease and as hardy as hawthorn.

Best known was the Bridal wreath, Spiraea arguta. It forms a large, 7-8 ft high shrub and, during May, covers its arched branches in pure white flowers.

The variety S.japonica ‘Anthony Waterer’ was also popular with its deep pink flowers and green leaves that were sometimes edged white. I never appreciated this plant and its demise is not regretted.

Spiraeas love a sunny spot in the garden preferring a well drained soil. Annual spring feeding with a balanced fertilizer and a mulch of well rotted, farmyard manure in autumn will result in a good show of flowers.

Most species flower on growths made the previous year and should be pruned in early summer removing those stems that flowered. Older plants can be thinned out removing a quarter of the oldest branches as close to ground level as possible. Spiraea douglasii flowers on the new growths and should be pruned in spring and fed with a balanced fertilizer to encourage growth.

With the onset of the multi coloured foliage varieties and dwarf shrubs spiraeas once again featured in garden designs. Their popularity has gone from strength to strength and no garden should be without at least one variety.

A personal favourite is Spiraea japonica ‘Gold Flame’. Its young, emerging leaves are bronze-red turning sulphur-yellow and then a light green. The dark pink flowers are less conspicuous. ‘Golden Princess’ is similar but by early summer its foliage is bright yellow.

The variety ‘Little Princess’ is low growing forming a 2 ft high, dense mound of mid-green leaves with rose-pink flowers in summer. Even lower growing is S. j. ‘Nana’ with dark pink flowers, 18 inches high with a similar spread.

For something totally different grow the attractive S. j. ‘Shirobana’.Its party trick is to produce all white and all dark pink flowers at the same time on the same plant.

The spiraea twins are S. x vanhouttei and S. thunbergii. Both grow to 5-6 ft in height with arching sprays of white flowers in early summer. The latter may flower a few days before vanhouttei that has darker green foliage. The double white, spring flowering S. prunifolia has the added advantage of good autumn colour in shades of yellow, orange and red.

Be careful with S. douglasii. The attractive deep pink flowers appear in mid-summer but it has an unfortunate habit of suckering. That’s fine if you want to give rooted pieces to friends but left alone it makes a big clump.

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