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never seen before & figuring out how to make them perform.- The Boston Globe

…Louis Raymond ensures that trees can grow in Brooklyn…

or just about any other place where concrete consumes

the dirt and skyscrapers shield the sunshine.- USA Today


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Plant Profiles

Unique Standards of 'Unique' Tree Hydrangea



A bush, a stepladder, a pyramid: Sometimes, just planting a 'Unique' panicle hydrangea isn't unique enough.  This is one of a quartet of 'Unique' panicles, two at either end of the reflecting pool.  Each is being trained up a vertical metal stake.  August by August, the bushes have bloomed at whatever height they've reached so far; they're finally tall enough to be tied clear to the pyramid's top.


A few of the tallest branches will be tied to the center stake, and the rest cut off. 




And while I'm here, why not untie all the stems to get the entire bush reorganized and really stabilized for its taller-than-ever performance?




With all the old ties cut away, the hydrangea is ready for some serious reworking.  But first, more about that pyramid.  There are yews planted at each of its inside corners.  As they grow up and out—through the chickenwire, too—they'll hide the hydrangea trunks as they fill out the pyramid.




in a few years, only the head of the hydrangea will be visible, as a huge billowing poof at the tippy top of the pyramid.


With a few of this year's hydrangea stems now tied to the top of the pyramid, and all the lower branches removed, the remaining growth that's still above the pyramid can be pruned.  Hydrangeas bloom exclusively at the tips of new growth, anyway, so the growth of the past season is only useful if the bush needs to become taller.  But it's now as tall as the pyramid and then some, so I can prune without mercy.




When growth resumes in Spring, several flowering stems will spring from every stub; next August's display of flowers will be bigger—and taller—than ever.




Here's how to grow this easy-to-train hydrangea:

Latin Name

Hydrangea paniculata 'Unique'

Common Name

'Unique' panicle hydrangea, grown as a standard


Hydrangeaceae, the Hydrangea family.

What kind of plant is it?

Deciduous shrub.


Zones 3 - 9.


If growing free-range: Tall and wide, with jumbled and awkward branching.  Smaller and more coherent when pruned; see "How to handle it" below for options. 

Rate of Growth


Size in ten years

If growing free-range, 10 to 13 feet high as well as wide.  Best when pruned; see "How to handle it" below. 


Messy when out of leaf; medium in leaf; definitively fluffy in August bloom.

Grown for

its flowers:  Huge heads of larger sterile flowers and smaller fertile flowers, beginning as pure white but pinking-up somewhat with age.  'Unique' is by no means one of "the" pink panicle; other cultivars turn pink sooner, or turn a deeper shade of pink.  See "Variants" below.  In full flower, the bush is visible from the next block; depending on its siting and handling, it could be a triumph of focal siting or a bulbous eyesore.  


its flexibility:  Because flowering is at the tips of new growth only, the bush can be pruned variously and to great effect.  See "How to handle it" below.


its hardiness: Zone 3 means northern Vermont, let alone southern Saskatchewan.

Flowering season

High Summer: August here in Rhode Island.

Color combinations

'Unique' is green in leaf, adding white in high Summer when the blooms are fresh.  So far, then, it goes with everything.  By September the flowers have become a dusty pink, causing the most fastidious and uncompromising colorists to have sited the bush only with neighbors who were pink-friendly from the start:  Blue-needled conifers and blue-foliaged deciduous shrubs.  Pink-plumed ornamental grasses, and rose and pink-flowered late-season shrubs, perennials, and annuals, such as rose-of-sharon, dahlias, asters, roses, and mums. 


I take the easier route: the minute Fall seems imminent—which, self-servingly, I define as when the panicles begin to pink—I decide that it's easiest to ditch most of my warm-weather coloristic rigidity.  Pink by yellow by red by blue?  Whatever:  At least it's color.  This all the more fortunate in that my quartet of 'Unique' panicle standards flanks what will, some day, become a gigantic yellow border.  And if there's any color that can be had more plentifully and in even more strident saturation in September than August, it's yellow.  Yellow and pink:  Yuck.  I'll try dead-heading the standards before their pink has become, so to speak, beyond the pale. 

Partner plants

Panicle hydrangeas are big-boned, and when they're in bloom the bushes are the definition of voluptuous.  It's exciting, therefore, to combine them with plants whose growth and habit are (at least by comparison) disciplined and finely-detailed.  Just be sure that "disciplined and finely-detailed" doesn't also mean small-scale.  Even a sternly-pruned hydrangea is a billowing creature, and attempts to restrain its spread will defeat the whole look of overflowing generosity of display.


Because hydrangeas don't appreciate having to scrounge for water, you could partner with plants that also welcome rich soil.  Ferns, say. 

A large foreground group of them would be terrific.  If the hydrangea billows out over them, they'll be just as happy with that bit of shade.  Or consider a large group of taller hardy ferns—ostrich or royal—to one side.  Ornamental grasses are another natural partner, not least because so many will also be in bloom in August. 


Because the huge flowerheads will cause hydrangeas to wave in the breeze, some partner plants should be contrastingly solid, even rigid.  Holly and box have the right combination of smaller foliage and solid fullness; they have a graceful but firm territoriality that tolerates some hydrangea encroachment in August and September.


A well-pruned hedge is the universal accompaniment to horticulture.  For a bush such as panicle hydrangeas, whose peak performance is in high Summer, privet is just as good as anything evergreen (although, true, it's no more attractive than the hydrangea in Winter).  Arborvitae or yew would be the ultimate, with tiny foliage, uncompromising discipline (thanks to you, the pruner), and sufficient size.

Where to use it in your garden

A panicle hydrangea in full-bloom is automatically an eyeful; plant it where you truly want your eyes to be drawn.  The shrub is so hardy, and so happy to be pruned way back each Spring, that you could also grow it in in large containers that sit outside year-round.  Just be sure you keep up with the watering.


Any decent soil and plenty of sun.  Hydrangeas aren't drought-tolerant, so if your weather's routinely a scorcher, grow in rich soil, mulch well, and water faithfully.

How to handle it: The Basics

The worst treatment for a panicle hydrangea is neglect.  The bushes grow so fast, and their free-range branching is so coarse, that they quickly become an eyesore. 


The most important care you can provide is Spring pruning.  Panicles are very accommodating, because they bloom exclusively at the tips of the current season's growth.  What to do with the wood grown last year, then, depends on how big a bush you'd like to have this year.


If low and bushy is the goal, cut the bush down to a foot in early Spring, and it will be four or five feet tall and wide by the time it's in bloom in August.


Shorter still?  Also pinch the new stems in late May or early June.


Somewhat taller?  Cut back last year's stems just to two or three feet.


Really tall?  The branches of panicle hydrangeas are truly woody and, with age, even trunk-like.  Take advantage of the wood's strength and durability to elevate the new growth by creating a hydrangea standard.  Select just one main stem and stake it; cut the rest of at the base.  After the main stem has grown and been tied to the height you like—about eight feet, for me—then long-term care after that is largely about cutting the previous year's growth back to stubs in the Fall or Spring.  Remove other stems anytime they appear at the base or on the trunk.

In forming my standards, I've tied in several main branches to get a fuller head quicker, but over time a single-trunk standard will be just as full.


No matter what height you're shooting for, it's still a good trick to pinch the new stems in early June.  The flowerheads they produce will be smaller, and so less floppy.  The cultivar 'Little Lamb' naturally produces smaller flower clusters—but it's also a smaller bush overall.  To get a full-size bush and non-floppy flowerheads, you need to pinch the new growth in June.


Fastidious folks dead-head the bush as the flowers age from pink to brown, but others enjoy letting the flowers dry to brown right on the bush.

How to handle it: Another option—or two?

You could combine both pruning strategies, to produce a high and trunky central stem trained into a standard, and also leave the stems that will still sprout up from the base, cutting them down to a foot each Spring as you'd do for a low-and-bushy panicle.  Then you would have a two-tier effect, like a gigantic horticultural epergne.

Quirks or special cases



The flowerheads are so large that their stems can droop or even snap.  See "How to handle it" above for the solution.


What diversity has come to panicle hydrangeas!  When I was an adolescent way back when—the late Sixties—I don't recall anything but the vanilla H. paniculata 'Grandiflora', which was everywhere.


Cultivars began appearing in the Seventies, and an Eighties trickle turned into a stream by the Nineties, and in the 2000's, a flood.  Fifty and more cultivars are now on the market.  Blooming can start as early as May or as late as late September.  The flower clusters can be as small as your fist or as big as soccer balls.  In addition to the usual white, flower color can be various shades of pink (and white that turns into pink sooner, or from the top of the cluster down), or lime green that turns to pink but not as fast as others.  Stems can be stiffer or floppier, and overall size dwarfer or not.  The individual sterile flowers—the large ones in the cluster—can be larger; those of 'The Swan' are each as big as your palm. 


Despite this panoply, I'm limping along with just 'The Swan', 'Pink Diamond', and 'Unique'.  Shameful, I admit.   


On-line and at retailers.


Hydrangea cultivars are propagated by cuttings.

Native habitat

Hydrangea paniculata is native to East Asia. 

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