A Complete Guide to the Most Rewarding Shrub in the Temperate Garden
The hydrangea has had a curious relationship with fashion. For much of the twentieth century it was the shrub of seaside boarding houses and suburban front gardens — admired for its reliability, patronised for its obviousness, planted without much thought and allowed to become shapeless mounds of faded colour that nobody quite got around to removing. Then, somewhere in the 1990s and early 2000s, the design world rediscovered it. Dutch and German garden designers began using mophead hydrangeas in vast, repetitive drifts. Florists discovered the dried head as a structural element of enduring beauty. Breeders released dozens of new varieties of previously obscure species. And the hydrangea found itself, almost overnight, transformed from a slightly embarrassing inheritance into the most sought-after shrub in the garden centre.
Neither the dismissal nor the rehabilitation quite does justice to what the hydrangea actually is: a genus of exceptional breadth and variety, encompassing plants as different as the climbing H. anomala subsp. petiolaris and the lacy-capped serrata cultivars, containing species adapted to everything from full shade to full sun, and offering a flowering season that runs from June to the first hard frosts, with dried heads providing structural interest well into winter. To understand the hydrangea properly is to understand that you have been dealing, all along, with a plant of genuine complexity and remarkable garden usefulness — and that most people have been growing only a small fraction of what is available.
Origins and Exploration
The genus Hydrangea is native primarily to Asia — China, Japan and Korea — with a secondary centre of diversity in North and South America. It was European plant hunters working in Asia in the eighteenth and nineteenth centuries who brought the genus into Western cultivation, and the story of how hydrangeas reached our gardens is inseparable from the broader story of botanical exploration in the Far East.
Hydrangea macrophylla — the species from which all mophead and lacecap garden hydrangeas derive — is native to coastal Japan, where it grows wild on cliff edges and in open scrubland within reach of the sea. It was first described botanically by the Swedish naturalist Carl Peter Thunberg, who visited Japan in the 1770s as part of the Dutch East India Company mission and documented numerous plants previously unknown to European science. The first living plants reached Britain in 1789, arriving via the botanist Joseph Banks — the same Banks who had sailed with Cook on the Endeavour — who obtained them through the East India Company’s network of contacts in China.
The Japanese connection was deepened and complicated by the work of Philipp Franz von Siebold, a German physician and naturalist who spent seven years in Japan from 1823, during which time he assembled the most comprehensive collection of Japanese plants ever brought to Europe. Von Siebold named one of his hydrangea discoveries after his Japanese companion Otaksa, in a gesture of botanical romanticism that the formal naming conventions of science eventually overruled but did not entirely suppress. His introductions included what would eventually be classified as Hydrangea serrata — the mountain hydrangea — and numerous other species and forms.
The North American species — Hydrangea arborescens and H. quercifolia — had their own separate introduction history. H. arborescens is native to the eastern United States, where it grows in woodland margins and along stream banks, and was known to European science from the early eighteenth century. H. quercifolia, the oakleaf hydrangea, was described by the botanist William Bartram during his explorations of the American southeast in the 1770s and introduced to cultivation shortly afterward. Both species found their most appreciative audience not in their homeland but in European gardens, where their particular qualities — woodland tolerance, extraordinary autumn colour in the case of quercifolia, reblooming vigour in the case of arborescens — were recognised and exploited with enthusiasm.
Understanding Hydrangea Types
The genus Hydrangea encompasses several distinct species of garden importance, and the differences between them are significant enough that treating them as a single plant category produces confused and often disappointing results. Each major species group has its own requirements, its own characteristic beauties, and its own appropriate garden context.
Hydrangea macrophylla — mopheads and lacecaps. This is the hydrangea most people picture when they hear the word — the large-flowered shrub of coastal gardens, seaside towns and suburban borders. The species divides naturally into two groups: hortensias, or mopheads, in which all the flowers in a head are large, showy sterile florets that form the familiar dome-shaped or globular flower head; and lacecaps, in which the flat flower head has a ring of large sterile florets around a centre of tiny, fertile flowers. The distinction is not merely aesthetic: lacecaps are generally held by experienced gardeners to be the more refined and garden-worthy of the two forms, their delicate, flat-headed flowers reading as more sophisticated than the blowsy mopheads, though the mophead’s capacity for extended display — the dried heads remaining attractive for months — has its own considerable argument.
Hydrangea serrata — mountain hydrangea. The serrata species and its cultivars are closely related to macrophylla but smaller, more compact and hardier, with flowers of greater delicacy. They are native to mountain woodland in Japan and Korea and have an innate quality of refinement that places them in a different aesthetic category from the coastal macrophyllas. Serrata cultivars — ‘Bluebird’, ‘Tiara’, ‘Miranda’ — are among the most beautiful shrubs in the genus and deserve considerably wider planting than they currently receive.
Hydrangea paniculata — panicle hydrangea. Distinct from both macrophylla and serrata in flower form — its flowers are borne in large, elongated cone-shaped panicles rather than flat or dome-shaped heads — H. paniculata is native to China, Japan and Russia and is the hardiest of the large-flowered species. It blooms on the current year’s growth, which means that hard pruning in spring produces the largest flowers and that late frosts — the bane of macrophylla growers — pose no threat to the season’s display. It is also the most tolerant of full sun and alkaline soil, making it useful where other hydrangeas struggle.
Hydrangea arborescens — smooth hydrangea. Native to eastern North America, this species is grown primarily in its cultivated forms, most notably ‘Annabelle’ — a variety that has achieved something approaching iconic status in modern garden design for its enormous, pure white spherical flower heads, produced from July to September on a neat, reliably hardy shrub. Like paniculata, it flowers on the current year’s growth and can be cut back hard each spring. It is among the most shade-tolerant of the genus and one of the most reliably garden-useful.
Hydrangea quercifolia — oakleaf hydrangea. Named for its deeply lobed, oak-shaped leaves, this North American species is grown as much for its foliage and autumn colour as for its flowers. The leaves turn spectacular shades of bronze, crimson and burgundy in autumn and persist late into the season; the flower heads, produced in June and July, are conical and white, fading to pink and then to a warm parchment-brown that is beautiful when dried. It requires more warmth than some of the other species to perform at its best and is most reliable in southern and eastern England.
Hydrangea anomala subsp. petiolaris — climbing hydrangea. Quite distinct from all the shrubby species, this self-clinging climber is one of the most valuable of all plants for north- and east-facing walls. It attaches itself by aerial roots, requires no tying in once established, and produces flattened, lacecap-like white flowers in June over a long season. Slow to establish — it can spend its first two or three years apparently doing very little — it eventually covers large areas of wall or fence and creates a spectacle of great beauty. Patience is the one non-negotiable requirement.
The Colour Question
The colour behaviour of hydrangeas is one of the most misunderstood aspects of the genus, and addressing it clearly prevents a great deal of disappointment.
Macrophylla and serrata hydrangeas are unique among garden plants in that their flower colour — whether pink or blue — is determined not by genetics alone but by soil chemistry. Specifically, it is determined by the availability of aluminium ions in the soil, which in turn depends on soil pH. In acid soils, where aluminium is freely available for uptake by the plant, flowers are blue. In alkaline soils, where aluminium availability is restricted, flowers are pink. In neutral soils, the flowers are often a muddy intermediate — mauve or indeterminate purple — that satisfies neither preference.
White-flowered varieties of macrophylla and serrata are not affected by soil pH — their white colouration is fixed by genetics and does not change regardless of soil conditions.
This has immediate practical implications. A blue hydrangea purchased from a nursery in an ericaceous compost will turn pink when planted in alkaline or neutral garden soil, often to the bewilderment and disappointment of its new owner. Conversely, a pink hydrangea will blue up over time in acid soil. For gardeners with neutral or alkaline soil who want blue flowers, aluminium sulphate can be applied to the soil to lower pH and increase aluminium availability — proprietary hydrangea colourants are essentially aluminium sulphate in a convenient form — but maintaining blue flowers long-term in alkaline soil is a constant battle. The more honest advice is to accept the flowers in whatever colour your soil produces, or to grow plants in containers where the compost pH can be controlled precisely.
Hydrangea paniculata, arborescens and quercifolia are not affected by soil pH in this way. Their flowers are white, cream or greenish-white when they open, fading through pink to parchment and bronze as they age — a process driven by the chemistry of the flowers themselves rather than by soil conditions.
The ageing process in hydrangea flowers is one of the genus’s most appealing characteristics. Very few garden plants produce a display that improves and becomes more complex as it ages. Hydrangea paniculata ‘Limelight’ opens a fresh acid-green in late summer, turns white, then blushes through pink to a warm antique rose by October. ‘Annabelle’ opens green-white and passes through pure white to a beautiful parchment-beige that dries perfectly on the plant. The mopheads of macrophylla turn from their fresh summer colour — blue, pink or white — to antique shades of burgundy, blue-green and warm copper by autumn. These are flowers that earn their keep across four or five months in a way that most flowering shrubs do not.
The Essential Varieties: Hydrangea macrophylla
‘Annabelle’ — a clarification is necessary here: the famous ‘Annabelle’ is in fact a variety of Hydrangea arborescens, not macrophylla, though it is so often discussed alongside macrophylla cultivars that the confusion is forgivable. It is addressed fully in its proper section below.
‘Nikko Blue’ is the classic large mophead in pure, saturated blue — one of the most reliably blue-flowering macrophyllas in acid soil and one of the best mopheads for the traditional seaside garden effect.
‘Endless Summer’ was the first of the remontant mophead hydrangeas — a breeding breakthrough that addressed the frustrating susceptibility of macrophylla to late-frost damage by producing a plant that flowers on both old and new wood, meaning a single frost event that destroys the old wood buds does not eliminate the whole season’s display. It has since been followed by numerous other remontant varieties, and for gardens in frost-prone inland positions, the remontant types are now the sensible default.
‘Ayesha’ is one of the most unusual of all macrophylla cultivars — its sterile florets are concave and cup-shaped rather than flat, resembling small lilac florets more than typical hydrangea flowers, giving the whole head a distinctive, slightly waxy character. The fragrance — unusual in the genus — is light but genuine. Pink in alkaline soil, lilac-blue in acid.
‘Mariesii Perfecta’ (also sold as ‘Blue Wave’) is among the finest lacecap hydrangeas — vigorous, with large heads of blue fertile flowers surrounded by a ring of clear blue sterile florets. One of the best lacecaps for sustained garden effect.
‘Lanarth White’ is a white lacecap of great elegance — flat heads of pure white sterile florets around a centre of white and cream. One of the most refined of all macrophylla cultivars.
‘Geoffrey Chadbund’ is a red-flowered lacecap — a colour unusual in the lacecap form — with flat heads of brick-red sterile florets. It maintains its red colouring reliably in most soil conditions, making it useful where colour stability matters.
‘Zorro’ is a black-stemmed lacecap — the contrast between the very dark, near-black stems and the blue-pink lacecap flowers is striking and unlike anything else the genus offers.
The Essential Varieties: Hydrangea serrata
‘Bluebird’ is perhaps the finest serrata lacecap — compact, with flat heads of blue fertile flowers surrounded by a ring of pale blue-white sterile florets. The heads are smaller and more refined than macrophylla lacecaps, and the whole plant has an elegance appropriate to its mountain origins.
‘Tiara’ produces heads with a double ring of sterile florets around the fertile centre — an unusual and beautiful flower form that makes this variety stand out even in a genus not short of visual interest.
‘Miyama-yae-Murasaki’ (also sold as ‘Fuji Waterfall’ or under various alternative names) bears loose, double-flowered sterile florets of a delicate white-tinged pink in pendulous clusters — an exquisite variety that looks quite unlike any other hydrangea in the garden.
‘Grayswood’ is distinguished as much by its leaf colour — the leaves take on rich autumn tints of red and burgundy — as by its white-turning-crimson lacecap flowers. One of the most garden-worthy of all autumn-colouring shrubs.
The Essential Varieties: Hydrangea paniculata
‘Limelight’ is the variety that transformed garden designers’ understanding of what H. paniculata could contribute to the modern border. Its enormous, elongated flower panicles open in a fresh acid-lime green in late July, turn white in August, and flush pink and then burgundy-rose as autumn develops — a four-month colour performance of exceptional range. It is vigorous, hardy, reliable and now widely considered the most garden-worthy of all hydrangeas by many experienced practitioners.
‘Grandiflora’ (PeeGee hydrangea) is the traditional large-panicled form — enormous white panicles that can reach 35cm in length on mature, hard-pruned plants. The original large-flowered paniculata and still one of the most dramatic.
‘Phantom’ produces the largest flower heads of any paniculata — pure white, slightly more rounded in form than ‘Grandiflora’, of extraordinary size on pruned plants. For maximum impact on a single specimen, this is the variety to choose.
‘Vanille Fraise’ is perhaps the most colourful of the paniculate hydrangeas, with flowers that open white and develop vivid strawberry-red flushing on the lower portions of the panicle as the season progresses, creating an attractive two-tone effect.
‘Little Lime’ is a compact form of ‘Limelight’ — reaching 1 to 1.2 metres rather than the full 1.8 to 2 metres of the parent — that has made the variety accessible to smaller gardens and containers. It is one of the most useful new introductions of recent years.
‘Quick Fire’ is the earliest-flowering paniculata, beginning its display in mid-July — three to four weeks earlier than most other varieties — giving a noticeably extended season.
The Essential Varieties: Hydrangea arborescens
‘Annabelle’ remains the benchmark of the species and one of the most widely planted shrubs in contemporary garden design. Its enormous spherical flower heads — 25 to 30cm across on a well-grown plant — are produced in extraordinary quantity from July to September, opening a fresh green before turning pure white and finally fading to a warm parchment-beige. It is completely hardy, tolerates shade, flowers reliably every year regardless of winter temperatures, and produces its finest display when cut back hard to 30cm in late winter. It does have one acknowledged weakness: the flower heads are so heavy that they weigh the stems down in rain, causing the plant to collapse forward. This is partly managed by hard pruning — which produces shorter, sturdier stems — and partly by accepting that Annabelle after heavy rain requires gentle staking until it dries.
‘Incrediball’ is a relatively recent introduction bred to address Annabelle’s stem weakness — it produces heads at least as large but on sturdier stems with stronger wood, and it stands up considerably better in wet weather. Now widely considered the superior garden plant to Annabelle for most situations.
‘Hayes Starburst’ bears double-flowered white heads of particular delicacy — each individual sterile floret is fully double, giving the whole head a lacy, frothy quality different from the rounded heads of Annabelle and Incrediball.
The Essential Varieties: Hydrangea quercifolia
‘Snow Queen’ is the most widely planted oakleaf hydrangea — large, elongated white panicles above the deeply lobed foliage, with outstanding autumn colour in shades of crimson, bronze and burgundy. Reliable in a sheltered position in southern England.
‘Snowflake’ bears double-flowered panicles — each floret doubled — of remarkable persistence, remaining attractive on the plant into late autumn before transitioning to the characteristic parchment tones of dried oakleaf flowers.
‘Ruby Slippers’ is a more compact form with flowers that turn a particularly deep pink-red before fading, combined with reliable autumn leaf colour. One of the best for smaller gardens where the species size is a concern.
In the Garden: How to Use Them
The hydrangea’s range of species, sizes and flowering periods makes it one of the most versatile of all garden shrubs, but this versatility is wasted if all varieties are treated identically. Matching the right species and variety to the right garden context is the key to getting the best from the genus.
Shade planting is where H. anomala petiolaris and H. arborescens are unrivalled. The climbing hydrangea will cover a north-facing wall that defeats most plants, producing its white lacecap flowers in June with a generosity that justifies the two or three years of establishment patience it demands. ‘Annabelle’ and ‘Incrediball’ perform better in shade than almost any other large-flowered shrub, making them invaluable in the north-facing border or beneath the canopy of trees. H. macrophylla also tolerates more shade than most, and its flower colours are often richer and more lasting in dappled shade than in full sun.
The modern naturalistic border has adopted H. paniculata as one of its structural elements, using varieties like ‘Limelight’ as large, flowering specimens that provide scale and late-season colour among ornamental grasses, Echinacea, Rudbeckia and Persicaria. The paniculata’s self-supporting stems, reliable flowering and four-month head season make it the most useful of all hydrangeas for mixed border planting, and its ability to be pruned to whatever size suits the space gives it a flexibility other large shrubs lack.
The woodland garden is the natural home of H. serrata — the mountain hydrangeas look entirely right among ferns, hostas, Trillium and the lighter-canopied woodland perennials, their refined flowers and relatively modest scale appropriate to the considered understatement of a well-made shade garden.
Container growing suits H. macrophylla particularly well and solves the pH problem elegantly — in a pot of appropriate ericaceous compost, the soil chemistry can be controlled precisely and maintained with annual repotting and correct watering. Containers of mophead hydrangeas are among the most effective seasonal plantings for a shaded terrace or courtyard where summer colour is otherwise difficult to achieve.
Hedging with H. paniculata — specifically the varieties of intermediate size such as ‘Limelight’ or ‘Phantom’, pruned annually to maintain shape — is a relatively recent practice that has produced some of the most impressive garden effects in contemporary British planting. A formal hedge of ‘Limelight’ in full August flower, the enormous lime-green panicles aligned in a continuous wall of colour, is an extraordinarily dramatic sight.
The dried flower garden should be built largely around hydrangeas, as the genus provides the finest dried heads of any flowering shrub. H. paniculata, H. arborescens and H. quercifolia all dry beautifully on the plant if left uncut into autumn and winter. H. macrophylla mopheads can be dried indoors — cut when the flowers have begun to develop their antique autumn colouring, place in a small amount of water and allow to dry slowly. The result, in deep burgundy, slate-blue and warm copper, is among the most beautiful dried flower material available.
Cultivation
Soil. Most hydrangeas are tolerant of a wide range of soil types, provided the ground is reasonably moisture-retentive and well-supplied with organic matter. H. macrophylla and H. serrata are not drought-tolerant — their large leaves transpire heavily and they wilt rapidly in dry spells — and they perform best in soils that retain moisture through summer. H. paniculata is more tolerant of dry conditions and alkaline soil than the macrophylla relatives. H. arborescens is the most tolerant of all, performing satisfactorily in almost any reasonable soil. H. quercifolia requires good drainage and is less tolerant of heavy, wet clay than the other species.
Sun and shade. H. macrophylla, H. serrata and H. arborescens all prefer dappled shade or morning sun with afternoon shade — in full sun, the flowers bleach rapidly and the plants wilt during hot spells. H. paniculata is the exception, preferring and tolerating full sun better than any other species; it flowers most freely and colours most richly in a sunny position. H. anomala petiolaris, as a self-clinging climber, succeeds in almost any aspect including north-facing, though it flowers most freely in lighter conditions.
Watering. H. macrophylla and serrata must be watered during dry spells until thoroughly established and will require occasional watering in drought conditions even as mature plants. Wilting leaves in the morning — as opposed to the afternoon wilting that even well-watered plants show in heat — indicate that the plant genuinely needs water. Mulching around the root zone in spring significantly reduces water requirements.
Pruning: the critical distinction. This is where the greatest confusion arises, and it is important because the wrong pruning approach on the wrong species can eliminate an entire season’s flowering.
H. macrophylla and H. serrata flower on the previous year’s wood — the buds that carry the current summer’s flowers were formed during the previous summer on existing stems. Cutting these plants back hard in winter or early spring removes all the flowering wood and produces a season of foliage but no flowers. The correct approach is light pruning only — removing dead wood, cutting back any frost-damaged stem tips to the first live pair of buds, and removing a few of the oldest stems at the base every two or three years to encourage renewal. The golden rule: if you are unsure what to prune, prune as little as possible.
H. paniculata and H. arborescens, by contrast, flower on the current year’s growth — buds formed in spring on new stems carry the season’s flowers. They can be cut back hard in late winter or early spring — to 30cm from the ground for arborescens, or to a low framework of permanent branches for paniculata — and will produce vigorous new growth carrying large flowers by summer. This hard pruning produces the largest individual flower heads; lighter pruning produces more numerous but smaller heads on taller plants.
H. quercifolia flowers on old wood and should be treated like macrophylla — minimal pruning, restricted to removing dead wood and the oldest stems.
H. anomala petiolaris requires almost no pruning; simply remove dead or damaged stems and, occasionally, stems that are growing away from the wall.
Frost protection. H. macrophylla and serrata are the most vulnerable to late spring frosts, which can kill the newly emerging flower buds and eliminate the season’s display. In frost-prone gardens, a layer of horticultural fleece over established plants in late April and May during forecast frost nights provides effective protection. The remontant varieties, which flower on both old and new wood, are significantly more resilient in this respect.
The Drying and Pressing Tradition
The dried hydrangea head is among the most significant contributions the genus makes to the indoor decorative arts, and the tradition of drying and pressing hydrangea flowers for winter arrangements is centuries old in Japan, where the art form has a name — shiori — and a long history.
For home drying, cut paniculata and arborescens heads in September or October, when the flowers have developed their autumn colouring and the petals feel slightly papery to the touch. Place in a vase with a small amount of water and leave in a cool, dry, well-ventilated room — the flowers will dry naturally over two to three weeks without losing their colour or form. Macrophylla mopheads are best dried hanging upside down in a warm, dry place.
Dried hydrangea heads retain their colour and form for up to two years if kept out of direct sunlight and away from high humidity. They are among the most versatile elements in dried flower arrangement, combining with grasses, seed heads, dried alliums and the papery flowers of Honesty (Lunaria) in compositions of considerable sophistication.
Why the Hydrangea Deserves Its New Reputation
The hydrangea’s rehabilitation from suburban cliché to sophisticated garden plant is not merely a fashion cycle — it reflects a genuine reassessment of what the genus can do when it is understood rather than merely planted.
A well-chosen paniculata in the right border position provides four months of changing colour from July to November, requires minimal maintenance, tolerates conditions that defeat most flowering shrubs, and produces dried heads of winter beauty that extend its garden contribution to a full twelve months. A climbing H. petiolaris transforms a north-facing wall over ten years into a cascade of summer white. A serrata cultivar in woodland dapple produces flowers of a refinement that the most celebrated flowering shrubs rarely match. An ‘Annabelle’ or ‘Incrediball’ in the shaded border provides summer spectacle where little else will perform.
These are not the achievements of a plant that happened to be available at the right moment of fashion. They are the achievements of a genus that was always exceptional and simply had to wait for gardeners to notice.
Key macrophylla varieties: ‘Endless Summer’, ‘Nikko Blue’, ‘Ayesha’, ‘Mariesii Perfecta’, ‘Lanarth White’, ‘Zorro’, ‘Geoffrey Chadbund’.
Key serrata varieties: ‘Bluebird’, ‘Tiara’, ‘Grayswood’, ‘Miyama-yae-Murasaki’.
Key paniculata varieties: ‘Limelight’, ‘Phantom’, ‘Vanille Fraise’, ‘Little Lime’, ‘Quick Fire’, ‘Grandiflora’.
Key arborescens varieties: ‘Annabelle’, ‘Incrediball’, ‘Hayes Starburst’.
Key quercifolia varieties: ‘Snow Queen’, ‘Snowflake’, ‘Ruby Slippers’.
For sourcing, contact: Hillier Nurseries (hillier.co.uk), Burncoose Nurseries (burncoose.co.uk), or consult the RHS Plant Finder at rhsplantfinder.rhs.org.uk.
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