A Gardening Journal

The Best Season Ever: Fall Foliage of the Oakleaf Hydrangea

Hydrangea-quercifolia-Alice-hand-102710-640 

 

Oakleaf hydrangeas are such generous performers that their lovely panicles of flowers—normally the reason to grow any hydrangea—are just the icing on the cake. Their enormous oak-like foliage is unique even in such a large and diverse genus, and it develops spectacular Fall colors. Notice that the leaves above my hands—the very last that this stem grew before cool Fall weather arrived—are much darker than the leaves below. Apparently, a deep shiny burgundy color is the younger leaves' game; leaves formed earlier in the season turn much brighter hues: pinkish red or (see below) orange or yellow.

 

  

Hydrangea-quercifolia-Alice-Hakonechloa-macra-albo-striata-102710-640

 

 

With such a powerful and almost fluorescent display, it's easy to contrast with almost any other nearby foliage. In the photo above, the colors and texture of the white-striped Japanese forest grass strongly show up the comparative size and warm coloring of the hydrangea foliage.

 

In the picture below, the foliage and flowers one of the adult branches of a variegated adult ivy, Hedera colchica 'Sulphur Heart', shimmer in front of the hydrangea leaves. With Fall's cooler weather, foliage is more likely to stay wet from the rain, enhancing the glossiness of the foliage of both. 

 

Hydrangea-quercifolia-Alice-Hedera-colchica-Sulphur-Heart-102710-640 

 

As befitting such a generous shrub, you have many options to make the show of flowers and foliage of Hydrangea quercifolia even more exciting. 

 

Here's how to grow this extraordinarily showy shrub:

 

Latin name

Hydrangea quercifolia 'Alice'

Common name

'Alice' oakleaf hydrangea

Family

Hydrangeaceae, the Hydrangea family.

What kind of plant is it

Deciduous shrub.

Hardiness

Zones 5 to 9. From painful experience, I can vouch that smaller or newly-planted individuals are not nearly as hardy. See "How to handle it," below, for how to maximize hardiness right from the start.

Habit

Mounding and, after several years, diligently spreading.

Rate of growth

Fast when happy. Speed of growth (and overall size) is affected by siting, culture, and handling. See "Where to use it," both boxes of "How to handle it", and "Quirks and special cases," below.

Size in ten years

Eight to twelve feet tall—or higher—and wide. Even adolescent shrubs become stoloniferous, and after many years of enthusiastic growth can form colonies of indefinite width. 

Texture

Straight-laced folks might call the foliage coarse, but the rest of us think of it as distinctive, bold, and dramatic. When the leaves have fallen for the Winter, the branching of older individuals has its own muscular integrity, with thick stems, sparsely branched, forming a large and spreading mound. A large Hydrangea quercifolia in the dead of Winter is a welcome sight; in comparison, a large Hydrangea paniculata or macrophylla is just a lot of sticks.

Grown for

its foliage: With the exception of Hydrangea aborescens 'Emerald Lace' (whose leaf edges are irregularly lobed), the foliage of Hydrangea quercifolia is unique in this large shrub group in not being roundish with a single point at the end. Instead, the leaves have prominent lobes that are so pointy that they really do echo the leaves of many species of oaks. Quercus = oak; folia = leaves: Oakleaf, indeed.

 

Leaf size is affected by handling and siting. Like some Hydrangea macrophylla hybrids, whose foliage can be so intensely variegated that the appearance of flowers—normally a hydrangea's raison d'être—is usually a distraction, the foliage of Hydrangea quercifolia is so exceptional that the shrub can be grown just for foliage (and stems). See "Quirks and special cases," below.

 

As shown in the pictures above, Fall foliage color is usually spectacular; it, too, can be affected by siting and handling. See "Culture" and "Quirks and special cases," below.

 

 

its stems: The surface of first-year stems is a beautiful fuzzy cinnamon, which is in excellent contrast with the medium green of the foliage. In the second year, the bark lightens noticeably, with the darker fuzz now reduced to a subtly-appealing stipple. Older stems exfoliate, which is more eccentric than attractive. See "Quirks and special cases" for how to prune to enhance the display of bark itself, and the overall architecture of the branching that is revealed in the Winter.

 

 

its flowers: Along with those of Hydrangea paniculata, the panicles of flowers of Hydrangea quercifolia are unique among hydrangeas in being pointed instead of rounded. The coloring and life cycle of the flowers of both species is similar: They emerge creamy white, age over many weeks to deeper shades of pink and purple and, by Fall, dry in place to parchment brown. See "How to handle it: Another option—or two!" for ways to affect quantity and size of the flower clusters.  

 

 

its tolerance of shade: Provided it isn't drought-stressed, Hydrangea quercifolia will grow in full sun. But the shrub is larger in shade, with dramatically larger foliage, too. Its tolerance of deep and even "problem" shade is so impressive that the shrub is near the top of the very short list for use in sites too dark, even, for hostas or rhododendrons.

Flowering season

Early Summer: Late June into July, and persisting through Summer and Fall, with dried-in-place remnants enduring even through Winter. The creamy white flowers progress to pinkish purple and then to brown. The larger florets are the sterile ones; they are so numerous at the outer surface of the panicle that they nearly hide the smaller fertile florets at the interior. Fertile oakleaf hydrangea florets are mostly inaccessible to butterflies, but are favorites with bees.

Color combinations

The combination of cinnamon-colored new stems with the bold medium-green leaves is so satisfying that the shrub can be grown, by intention or as a result of Winter dieback, without flowers. See "Quirks and special cases," below. 

 

Flowers emerge creamy-white, which coordinates beautifully with the cinnamon and green of the stems and leaves. The preferred palette for neighbors of an oakleaf hydrangea that is only in leaf, or has just begun to flower, would be orange, burgundy, ebony, cream, and green. But by early Summer, the creamy flowers begin maturing to dusty pink and purple. Orange is no longer compatible, but burgundy, ebony, cream, and green still are. In Fall, the pink-purple flowers change to parchment brown, and the green foliage turns pink, red, orange, yellow and burgundy. Anything goes!

 

See "Plant partners" for color harmonies that work all season long, plus others that call out to the shrub's seasonally-changing palettes. 

Partner plants

Because Hydrangea quercifolia is best with a bit of shade—or even a lot—its partner plants need to welcome shade, too. Most oakleafs are grown with the expectation of flowers, so companions with coloring from July to frost other than the neutrals of green and cream will need to be pink-friendly in Summer and Fall, not just shade-loving. In addition to the usual pink shade-loving annuals (impatiens, begonias, and caladiums) you could choose among hardy plants such as pink-flowered forms of Anemone japonica or any of the cultivars of Astilbe chinensis, which are in bloom a month and more later than the May-and-June flowers of the Arendsii hybrids.

 

Shade-tolerant plants with burgundy foliage into late Summer include fancy-leaved begonias, dark-leaved colocasias, and some cultivars of Ligularia, such as 'Brit Marie Crawford'. If you are growing Hydrangea quercifolia as a foliage plant (see "Quirks and special cases," below), bring plants that celebrate copper and orange near the hydrangea's cinnamon-barked new stems. There are endless cultivars of daylily to consider for the sunny side of the hydrangea, with orange-friendly flowers from early June nearly to September. If you are ambitious enough to grow orchids, they would welcome the same dappled shade as the hydrangea. Why not grow a couple of Summer-bloomers whose flowers echo the shrub's cinnamon stems? And then there's the cinnamon fern, itself, Osmundastrum cinnamomeum: Its stiffly-upright fertile fronds are just the right hue, and the plant craves as much shade as the hydrangea. 

 

The real message of the suggestion of cinnamon fern is that striking partnerships with Hydrangea quercifolia are easy when their basis is mostly about form, texture, and scale. Even ferns without showy dark fertile fronds are terrific companions for oakleafs: The contrast of leaves that are ferny with those that are nearly tropical in size is fool-proof. Similarly, shade-tolerant ornamental grasses are winners, especially if they are variegated in white, not yellow. I paired my oakleaf with the white-variegated Hakonechloa macro 'Albo-striata'. You could try Carex morrowii 'Ice Dance' as well as the grassy-leaved perennial Liriope muscari 'Variegata'.

 

Shade-tolerant conifers are another way to bring contrasting narrow (as well as dark) foliage near the hydrangea. The needles of plum yews, Cephalotaxus harringtonia, are noticeably longer than those of true yews, which are all forms of Taxus. Just as helpfully, cultivars of plum yews are available in upright, prostrate, and mounding forms that all contrast well with the broad mounding profile of the hydrangea.  

Where to use it in your garden

Hydrangea quercifolia is peerless in the semi- or full-shade conditions it prefers. The foliage is larger than ever, and the shrub's looser habit displays the flower clusters to perfection. The shade can be provided by buildings just as well as by trees, making oakleaf hydrangeas particularly valuable in city gardens, where the shade can be dense as well as long-lasting. Because even "dwarf" oakleafs can be four feet tall and wide, and full-sized forms ten or twelve feet high and wide, the challenge for city gardens is giving this shrub the space it needs. Handily, pruning—whether to increase production of flowers or to exclude them entirely in favor of even more exciting foliage—also reduces overall size. See "How to handle it: Another option—or two," below, as well as "Quirks and special cases."

Culture

Rich soil with enough moisture that the shrub doesn't become drought-stressed. This combination is easiest to achieve when the shrub receives some degree of shade. Morning sun with afternoon shade works well, as does dappled or even fairly dense shade all day. 

 

Hydrangea quercifolia is unusual in not preferring more sun at the colder and more northerly portions of its hardiness range. From Maine to Florida, then, this shrub is happiest in shade. 

How to handle it: The Basics

In Zone 7 and warmer, Hydrangea quercifolia can be planted any time, Fall to Spring, that the soil is workable; in Zones 6 and 5, plant only in Spring. After planting, ensure sufficient water for establishment.

 

Shrubs bought at nurseries (as opposed to derived from divisions of established colonies) will likely have been brought into leaf ahead of schedule, either from being overwintered in a barely-above-freezing hoop house or, intentionally, to enhance their "curb appeal" at the beginning of the Spring selling season. They'll be at risk if planted in the garden too early without receiving overnight protection from the season's last malevolent frost. So it's a good trade-off to protect an oakleaf from a frost or two, thereby giving its roots a few weeks longer in Spring to establish.

 

Mulch heavily the first Fall; at any age and size, oakleafs in their first year of establishment are more likely to suffer some Winter die-back, or even death. Fortunately, even if the first Winter is horrendous, oakleafs that have been mulched thickly will usually be able to send up new stems from the base.

 

As with all hydrangeas but H. paniculata (which is so hardy it can be pruned even in the dead of Winter), wait until Spring to cut off Winter dieback from oakleafs. You don't have to wait until you see the green of the new leaves themselves; even the swelling of the leaf buds is proof enough. The new activity makes it easy to identify stems or step tips that lack it. Those are the dead ones, and can be pruned away with confidence.

 

Plants established where dieback isn't the norm need little if any pruning as long as they have enough roo; they can flourish on their own for years.

If size control is needed, consider the pruning strategies that also enhance production of flowers or foliage: See "How to handle it: Another option—or two," below, as well as "Quirks and special cases."

 

The flowers dry in place, and panicles can last through the Winter. The shrub doesn't care one way or another, but removing the panicles' skeletal remains in Spring is a nice gesture, leaving the stage clear for the shrub's exciting new foliage.

How to handle it: Another option—or two?

The flowers of oakleaf hydrangeas are thrilling, and it's understandable to want as many of them as possible. As is the case for most forms of hydrangea other than Hydrangea arborescens and Hydrangea paniculata, the buds for the flowers of Hydrangea quercifolia are formed in late Summer and Fall, and need to survive the Winter in order to mature to flowers next Spring and Summer. To maximize the number of panicles, then, you need both to maximize the number of stem tips, and to do what you can to ensure that they don't get killed in the coming Winter. 

 

Established oakleafs flower well on their own, but to increase the number of stems that will produce the terminal flower buds, cut a few of the oldest branches out entirely each year. Their removal creates gaps in the shrub's foliage canopy, so that more sun can reach into the base, from where new stems will arise. With the additional light, they'll grow all the more enthusiastically.

 

Do this pruning as those branches' flowers are just starting to change from cream to pink. This timing lets you enjoy the current year's flower display, and also gives the new shoots that your pruning will encourage all possible time to mature to the point of producing terminal flower buds that Fall. If you find that your growing season isn't long enough for those flower buds to form, grit your teeth and, in the future, prune out those branches earlier in the season, even if it means before they have flowered. In other words, forego this year's crop of flowers for the even better display that these branches' removal will make possible next year.

 

As a further temptation to prune, remember that the flower clusters at the tips of stems that have never flowered—young stems, in other words—tend to be larger than those on stems that have already flowered. These latter will be at the tips of side stems that branches begin forming in their second and subsequent years. Side-branch clusters are numerous, but they tend to be smaller.

 

Resist pruning Hydrangea quercifolia later in the season, which will only encourage growth of stems that won't mature enough to form flower buds, and may not even be mature enough to survive Winter. If your oakleaf's flowers have already matured to pink, it's probably too late to prune. Similarly, any pruning you do in Winter or Spring is likely to remove stems that have terminal flower buds, which will diminish the show in late Spring and early Summer.  

 

Pruning Hydrangea quercifolia to maximize flower production, then, normally takes place in a brief window, from as soon as you can bear it when the flowers are at their peak, to when those flowers have just started to develop their pink hues. It's only a few weeks, so be ready.

 

If you're gardening where Winter damage to stem tips—and therefore next season's flowers—is common, there isn't much you can do to protect such a large bush, overall. Plus, the branches of Hydrangea quercifolia don't lend themselves to being espaliered against a wall as well as, say, those of Magnolia grandiflora, which are long but flexible, and whose leaves and flowers are produced just as well from side branches as from branch tips.

 

You could, however, take advantage of this hydrangea's stoloniferous tendency. Plant one or even several of the shrubs right against a sheltering wall; west or south-facing would be the most protective. Mulch heavily to increase your chances of establishing the bushes, even though they may have significant tip or stem dieback over the Winter. If you're lucky, you'll be able to keep the hydrangeas alive until they are old enough to send out their stolons. In time, while growth that originates too far out from the wall might be killed back, growth from stolons that are nearest the wall will thrive. In effect, you'll have a hydrangea hedge growing right at the base of the wall. If you fasten a series of horizontal wires, spaced a foot apart, up the lower portion of the wall, you could lead young stems between the wires and the wall, holding them even closer to it. Real hydrangea maniacs could then fasten a sheet of wind-baffle fabric over the entire wall of now-conveniently-flatter growth, to increase the likelihood that the branches and their terminal buds will both get through the Winter.

 

More realistic ways to enhance the Winter hardiness of the terminal buds is to take advantage of the shrub's preference for shady and woodsy habitat. Are you blessed with a large specimen of American holly that has exposed the lower portion of its trunk over the years? Plant oakleafs beneath it. The tree's dense canopy will deflect cold wind and air falling down to the ground from higher elevations. If you plant other evergreens to the north and east of the Ilex opaca, they'll deflect similar cold blasts arriving at ground-level.

 

Hardiness is often a matter of degree, in all senses. The difference between failure and success is a matter of the synergy between your gardening prowess and your property's quirky micro-climate opportunities. 

Quirks or special cases

Remember, both the common and Latin names of this shrub are oakleaf hydrangea and not, say, "the only other hydrangea besides a PG whose fantastic flowers are arranged in pointed panicles, not mounded ones." Indeed, oakleaf foliage is unique among hydrangeas and, even, among plants overall. (Alas, there's no oak—Quercus hydrangeafolia, say—that can return the compliment. If there were, you could underplant it with, of course, Hydrangea quercifolia, creating a planting of unparalleled self-referential purity.)

 

Happily, you can grow Hydrangea quercifolia so as to make its already exceptional foliage even better. And, unlike the narrow window of pruning that helps maximize flower production, the pruning to maximize foliage can happen any time over weeks and even months.

 

The simplest option doesn't involve pruning at all: Site the shrub in shade, not sun. The lower light intensity stimulates production of leaves that can be nearly twice as large.

 

Gardeners who are more interventionist will be happy to know that pruning can have even greater effects on foliage. If your oakleaf is vigorous already, you could cut all stems down to just a few inches anytime from late Winter into early Spring. (Wait until your oakleaf is firmly established before subjecting it to such a surprise attack.) Yes, this also cuts off all the stems whose terminal buds would, otherwise, develop into flowers but, if the goal really is fantastic oakleaf foliage, who cares about them? The new stems will also have longer lengths of the attractive cinnamon-colored stem between pairs of those larger-than-ever leaves. Although pruning this way precludes flowers, but maximizes the performance of foliage and stems, for me, at least, the trade-off is more than equal.

 

Gradualists could choose, instead, to cut down to nubs each Spring just two or three of the shrub's oldest branches. This leaves in places branches old enough to produce flowers, while also ensuring a fresh supply of the first-year stems whose leaves are the boldest.

 

Yet another option is to coppice all stems, but only every other year. The first year, the oakleaf will produce exclusively new stems with the largest-possible leaves. The second year, those stems' leaves will be "just" the normal size, but the stems will produce panicles of flowers at their tips.

 

Still another tactic would be to coppice—incrementally or completely—in mid-Summer, not early Spring, when the flowers begin to transition from cream to pink. This is the hardest (and, therefore, most impressive) option, in that you'd be massacring the bush, seemingly, when its performance is at its best. You can't dally in doing such Summer coppicing, because the new growth needs all possible time to mature sufficiently to survive the Winter. If you're prompt as well as brave, and your growing season is long enough, you'll have your cake and eat it, too: There will be enough time for the new stems to mature to Winter-hardiness and even to produce the dormant terminal buds for next season's flowers, and you'll have had a Summer-into-Fall display of large-leaved young growth.

 

Whichever strategy you chose to help your oakleaf produce the most exciting warm-weather foliage, you'll also be helping it produce the most colorful Fall foliage, too. First-year stems do not develop terminal panicles of flowers; instead, the leaves at their tips  turn a strikingly deep shade of burgundy. They are highlighted beautifully by the raspberry, orange, pink, and red tones of the leaves farther down. Just as helpfully, by removing some or all of the very oldest (and, therefore, also the tallest) branches, your pruning will enhance the look of the shrub all Winter, by keeping the bush somewhat more compact, and composed more specifically of younger stems and their "young stem" bark.

 

Gardeners in Zone 5 can be especially grateful for any of these foliage-celebrating techniques, because their oakleafs may incur enough tip dieback in a normal Winter that flower clusters are few anyway. Hydrangea paniculata 'Grandiflora' and Hydrangea arborescens are both hardy even into the still-more-severe cold of Zone 3, let alone Zone 5, and there are all kinds of cultivars of each to explore. Let them carry the torch of hydrangeas grown for flowers. 

Downsides

Established oakleafs are reliably hardy even in the stern climate of Zone 5, where the lowest Winter temperature can be a numbing -20 degrees Fahrenheit. Plus, deciduous shrubs are, in general, even easier to establish when planted in Fall. Despite both truisms, Hydrangea quercifolia can fail when planted in Fall in Zones 6 and 5, even when planting in sizes (say, five-gallon pots) that would be expected to be large enough to have reached maximum hardiness. Hah! Colder than Zone 7, it is safest to plant oakleafs only in Spring. See "How to handle it," above.

 

The glorious Fall foliage certainly takes its time to fully release. Even after repeated frosts, the youngest leaves persist. Alas, they've lost most of their color, and droop in seeming exhaustion at the tips of the branches.  

Variants

Many! Hydrangea quercifolia is blessed with a number of features worth tracking: Flowers: density, size, doubling, speed of coloring from white to pink, depth and endurance of pink, and panicle size and position vis à vis the foliage. Overall shrub size: huge, medium, dwarf, even more dwarf. Foliage color in Spring and Summer: green, gold. Foliage color in Fall: pink, orange, red; plus duration of coloring and intensity of coloring.  

 

Even better, the species and its cultivars seem to mutate spontaneously and often. ('Alice' herself was a naturally-occuring form.) Plus, cross pollination is also a productive way to produce distinctly new forms.

 

With so many attractive features to develop, and a species that is so easy to develop, as well as to propagate (see below), it's no wonder that new forms of oakleaf hydrangea reach the market regularly. Despite this enormous activity, a form with variegated foliage is still unknown.

 

These are only some of the current choices: 'Pee Wee' and 'Sykes Dwarf' are truly small, at least by comparison: Three to four feet high and wide instead of ten to twelve, with smaller foliage and flower panicles, too. Leaves of 'Little Honey' are pure gold; in my modest experience, the shrub is painfully slow. The Fall foliage of 'Alison' is reported as being even more fluorescent in its red-burgundy coloring. The flowers of 'Late Hand' emerge a month later. The panicles of 'Vaughn's Lillie' are reported as being so large and heavy that they weigh the branches down; this doesn't seem nearly as important an attribute as this shrub's unique (for oakleafs) ability to rebloom in late Summer.

Availability

On-line and at retailers.

Propagation

By division: After several years, established shrubs develop stolons; rooted segments can be cut out and replanted in Spring or (in Zones 7 and warmer) Fall. Entire clumps can be dug, divided, and replanted almost any time during Fall, Winter, or Spring that the ground is workable. Smaller portions are more tender than larger: If you divide in Fall in Zone 6 and colder, rely on only the large central divisions to survive; perimeter portions that have produced only first-year stems might not. In any case, new shoots grow from roots so easily that Hydrangea quercifolia can be difficult to eradicate.

 

By layering: Weigh a branch down to the ground with stones, and cover some of the stem with soil.

 

By cuttings: Young shoots are reported to root well when harvested in mid-Summer.

 

By seed: Although cultivars will not come true, fresh seed is reported as germinating so readily that it can be sown directly in a garden bed. That said, I've never been aware of self-seeded Hydrangea quercifolia

 

By tissue culture: This is not the province of the home gardener (or even the plant geek), but it's how cultivars are propagated en masse.

Native habitat

Hydrangea quercifolia is native to the entire southeast of the United States, from North Carolina to Tennessee, and then southward from Florida to Louisiana. 'Alice' was identified by Michael Dirr on the campus of the University of Georgia, in Athens, Georgia, and is named for his wife.

 
 
FacebookTwitterRSS Feed

Stay in touch!

 

Sign up for twice-monthly eNews, plus notification of new posts:

 

* indicates required