The Hydrangea has 80 or more species of deciduous and evergreen shrubs and climbers. They originated from woodland in East Asia, and North and South America. Bear this in mind when looking at the best place to plant them, as they will grow far better in similar conditions to that of their origin. They are mainly grown for their large, showy flowerheads but many have ornimental flaky, peeling bark, and attractive foliage with good Autumn colour. The flat, domed or conical flowerheads comprise corymbs or panicles of both tiny fertile flowers and larger sterile flowers with showy, petal-like sepals.
Flower colour is affected by the relative availability of aluminium ions in the soil. Acid soils with a pH of less than 5.5 produce blue flowers; soils with a greater pH than this produce pink flowers. In more or less neutral soils, flower colour can be influenced by the addition of blueing compound. White flowers are not affected by pH. Use ericaceous compost when planting Hydrangeas with blue flowers in pots and incorporate it into the soil when preparing a border for plants needing acidic soil; feed them with ericaceous slow release or soluable fertiliser.
Hydrangeas are useful for a range of garden sites. They are excellent as specimen plants or in group plantings; in a shrub border, or in containers. Use the climbers to clothe a shaded wall or fence. The flowerheads may be dried for use in flower arrangements.
They can be fully hardy to frost hardy depending on the variety.
Grow Hydrangeas in moist but well-drained, moderately fertile, humus-rich soil in full sun or partial shade. Provide shelter form cold, drying winds. Some Hydrangeas will become chlorotic in shallow chalk soil.
Prune most species of Hydrangea in late winter or early spring, when dormant, remove misplaced or crossing shoots to maintain permanent healthy framework. When pruning Hydrangea macrophylla, ‘Preziosa and serrata cut back to first bud or pair of buds below each flowerhead . Once established, cut back a third to a quarter of old shoots to base in early or mid- spring. Hydrangea paniculata can be pruned as most species of hydrangea or cut back to permanent framework or, for subshrubs and for drastic renovation, cut back flowered stems to their base. Climbers can be pruned after flowering, or in late winter or early spring. Trim them to fit the available space; carry out renovation pruning as needed.
Cultivars of Hydrangea macrophylla are divided into two groups Lacecaps and “Hortensia” (Mopheads). “Lacecaps” have flattened flowerheads with small fertile flowers in the centre, surrounded by larger sterile flowers. “Hortensias” (Mopheads) have spherical flowerheads of large sterile flowers. Some cultivars of Hydrangea serrata are also desribed as Lacecaps.
Hydrangea macrophylla (Common hydrangea) is a rounded, deciduous shrub with ovate, dark green leaves. In mid and late summer bears flattened corymbs 15-20cms (6-8”) across, of a few pink sterile flowers and numerous blue or pink fertile flowers. Height 2m (6’) spread 2.5m (8’), fully hardy, origin Japan. Try ‘Blue Wave’ syn ‘Mariesii Perfecta’ produces rich blue to mauve or lilac-blue to pink sterile flowers and darker fertile flowers. Height 2m (6’) spread 2.5m (8’). ‘Lanarth White’ has pink to blue fertile flowers surrounded by pure white sterile flowers; height and spread 1.5m (5’). ‘Mariesii’ produces domed flowerheads of numerous pale pink to pale blue sterile flowers. Height and spread 1.2m (4’). ‘Selina’ a compact shrub with deep purple-bronze leaves and pink to red flowers; height 0.9m (3’). ‘Teller Pink’ produces deep pink or violet blue flower heads in mid-late summer, height 0.9-1.5m (3-5’) .
Or try subspecies serrata – compact, erect deciduous shrub, flattened corymbs, 5-10cm (2-4”) across wih a few pink or blue sterile flowers, open from summer to autumn. Height and spread 1-2m (4’), can withstand temeratures down to minus 5 degrees C; origin Japan. Serrata ‘Bluebird’ bears rich blue fertile flowers surroundnded by pale blue sterile flowers over a very long period and the leaves turn red in the autumn. errata ‘Veitchii’ has large flowerheads with white sterile flowers turning pink to red with age and will grow in alkaline soil as it is lime-tolerant. Serrata ‘Preziosa’ an upright, deciduous shrub with small, spherical corymbs of white sterile flowers 10-13cms (4-5”) across turning to rich red, blue or mauve on acid soil, are borne on dark stems in late summer. Height and spread 1.5m (5’).
Some examples of Hortensia (Mopheads) are ‘Pia’ which is a compact plant, producing bright red flowers with white centres. Height 60cm (24”), spread 1m (3’). ‘Bouquet Rose’ has pink to mauve flowers borne in large flower-heads on slender, arching stems; height and spread 1m (3’). ‘Ayesha’ has unusual lilac-like flowers with small, cupped pale pink to pale blue sepals. Height 1.5m (5’) spread 2m (6’). ‘Hamburg’ is a vigourous shrub, bearing large flowerheads of dark pink to dark blue with toothed sepals. The rose pink variety is happy in alkaline soil (Hamburg purple rose prefers acidic soil); height 1.5m (5’).
Hydrangea arborescens (Sevenbark) a rounded, deciduous shrub with long stalked, ovate green leaves, paler underneath. Domed or lateened corymbs, dull white mainly fertile flowers in summer. Can grow up to 2.5m (8’) tall and wide, origin East USA; fully hardy. ‘Annabelle’ has large spherical flower heads, can grow up to 20cm (8”) across comprising of mainly sterile creamy white flowers. ‘Grandiflora’ has smaller flowerheads than ‘Annabelle’ but larger sterile flowers.
Hydrangea paniculata is a vigorous, spreading to upright , deciduous shrub with large conical panicles, 7-20cm (3-8”) tall of creamy white fertile flowers and large, pinkish white sterile flowers borne in late summer, early autumn. (To obtain larger flowerheads on cultivars, cut back previous season’s shoots to within a few buds of the woody framework in spring.) Height 3-7m (10-22’), spread 2.5m (8’), origin Russia, China and Japan; fully hardy. ‘Kyushu’ is an erect shrub with glossy leaves, flowers and growth as above. ‘Pink Diamond’ has broad, open panicles, that can grow up to 30cm (12”) tall, of fertile and sterile flowers, creamy white at first, becoming deep pink with red reverse to the petals as they age. ‘Unique’ is similar to ‘Grandiflora’ but more vigorous, with large sterile flowers in flowerheads 20cm (8”). Height 2.5m– 4m (8’-13’) and spread 1.5m-2.5m (5’- 8’). ‘Limelight’ has very dense flowerheads that are white, flushed lime-green and then turn pink as the season progresses, height 1.65m (5.5’). ‘Vanille Fraise’ has fluffy, loose pyramid-shaped flower panicles, creamy white turning shades of pink as they age, flowers July-October, height 2.25m (4’).
Try Hydrangea quercifolia (Oak-leaved hydrangea) a deciduous mound-forming shrub with deeply lobed leaves, that can grow up to 20cm (8”) long, turning bronze-purple in autumn. From mid-summer to autumn, bears conical panicles, that can grow up to 25cm (10”) tall, of white fertile flowers and sterile flowers, the sterile flowers become pink-tinged with age. Height 2m (6’), spread 2.5m (8’), origin S.E. USA, fully hardy. ‘Snow Queen’ has profuse, large sterile flowers in dense, upright flowerheads.
Or plant Hydrangea Aspera an upright deciduous shrub, with narrow, ovate dark green leaves, can grow up to 25cm (10”) across, downy beneath. From late summer to autumn, bears flattened corymbs, that can grow up to 25cm (10”) across, of blue to purple fertile flowers, surrounded by white sometimes pink- to mauve-tinged sterile flowers. Can grow up to 3m (10’) tall and wide, origin East Asia; fully hardy. Subspecies sargentiana an upright, deciduous shrub with stout, bristly shoots and large ovate, very bristly, dark green leaves that can grow up to 25cm (10”) long. Flattened corymbs that can grow up to 23cm (9”) across, of blue to purple fertile flowers, surrounded by white sterile flowers, sometimes tinged purple, are produces from late summer to autumn. Height 3m (10’) or more, spread 2.2m -2.5m (7-8’), origin China, fully hardy. Villosa is a spreading to erect, deciduous shrub or small tree with narrow, velvety dark green leaves 9-24cm (3.5 -10”) long. In late sumer, bears flattened corymbs, 15cm (6”) across (often more), of blue-purple or rich blue fertile flowers and lilac-white or rose-lilac sterile flowers. Height and spread 1-4m – (4-12’), origin Tibet, China; fully hardy.
Give them a go they are spectacular!!