Louis Raymond experiments in his own gardens like

a mad scientist, searching out plants that most people have

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

 
 

NEW Trips to Take!

Myrtle's easy when the conditions are right.

 
 
 
 

NEW Plants to Try!

Louis tries to capture the exact words to describe the fleeting but deep pleasures to be found in these Summer-into-Autumn incredibles.

 
 
 
 

New Gardening to Do!

Allergic to bees? You can still have an exciting garden, full of flowers and color and wildlife.

 
 
 
 

Plant Profiles

Variegated London Planetree

platanus-suttneri-foliage-1-060312-640

 

The Spring and early Summer foliage of planetrees is striking, combining large, bright-green, sharply-pointy mature leaves with pastel and fuzzy juveniles.  Youngsters are sometimes near-white, and show up just as well against the green of the older leaves. 

 

platanus-suttneri-foliage-2-060312-640

 

The leaves of this variegated form, 'Suttneri', don't show their true colors, literally, until fully fledged.  No matter: The real thrill of the tree is its bark, which is wild even for a planetree.  Starting at the base of the trunk, the brown outer layer flakes away, revealing the icy-green whiteness beneath. 

 

platanus-suttneri-lower-trunk-just-starting-to-color-060312-640

 

My youngster has just begun its transformation.  Unlike most planetrees, which retain a patchy tan-and-white trunk for decades, the trunk of 'Suttneri' often progresses to pure white.  Stunning!

 

 

Here's an update on the extraordinary bark of Suttner's planetree, as well as shots of the fearless pruning needed to shape it into a pollard.

 

 

Here's how to grow this uniquely-colorful planetree:

 

 

Latin Name

Platanus x acerifolia 'Suttneri'

Common Name

Variegated London planetree

Family

Platanaceae, the planetree family.

What kind of plant is it?

Deciduous tree.

Hardiness

Zones 4 - 8.

Habit

Strongly upright and single-trunked, especially in youth and adolescence.  Widens considerably with age and, unless lower limbs are removed, matures into a wide and short-trunked specimen.

Rate of Growth

Medium to fast.

Size in ten years

If growing free-range, fifteen to twenty feet tall and twelve to fifteen feet wide.  See "How to handle it" for a strategy to control size as well as enhance the display of bark and foliage.

Texture

Despite the large leaves, the canopy is not dense.  'Suttneri' shows plenty of wood and branch.

Grown for

its foliage:  The leaves are typical in size and shape for unvariegated plane trees: eight to ten inches across, with three to five sharply-pointed lobes.  When mature, the leaves of 'Suttneri' are irregularly stippled in pale green; juvenile foliage is colorful because of an overall pink or white blush.  The variegation is showy only at close range; this isn't a variegated tree to plant for long-distance appeal, at least, not on account of its foliage.  See "How to handle it:  Another option—or two!" for a strategy that should both enhance and prolong the foliar display. 

 

its bark:  The real claim-to-fame of 'Suttneri' should be its bark, on which the literature, fixated on the modest variegation of the leaves, is silent to the point of provoking conspiracy theorizing.

 

The bark of 'Suttneri' is best appreciated in contrast to that of more typical Platanus species and cultivars.  Yes, their bark can be extremely showy, as very large flakes of tan outer bark separate from the limbs and the trunk, revealing creamy-white bark beneath.  Any given area of bark flakes just once; creamy areas of bark remain creamy as well as non-flaking.  The result is that the proportion of creamy bark to tan usually increases as the tree ages.  Very old trees, which are the largest and therefore have the most surface area, are doubly dramatic: They are both notably larger than younger trees as well as notably more colorful, because a higher percentage of their already-larger bark surface area has become creamy white.  Although the flaking progresses throughout the life of the tree, not all portions of the bark flake; even old trees retain irregular patches of their tan bark.  The oldest bark of exceptionally large individuals—which would be that of the lower main trunk—sometimes progresses to a third phase characterized by a more uniform brown color with vertical fissures instead of smooth flakes.

 

For three reasons, the bark of 'Suttneri' is remarkable even among planetrees.  First, it progresses through its brown-flake phase to the creamy-white phase at a much younger age.  Second, nearly all of the surface area of a given stretch of trunk or branch progresses to creamy-white.  Even adolescent trees, whose trunks might be, for a plane tree, a meager six inches in caliper, might display bark that is uniformly—and thrillingly—near-white.  And third, that white bark extends from ground level to the smaller branches high up in the canopy.

 

The showy bark of all forms of Platanus is the opposite of that of many other popular woody plants with showy bark, such as some species and cultivars of Acer, Cornus, Rubus, and SalixPlatanus bark becomes colorful only on older growth, whereas the bark of these others is showy only in extreme youth, often for just the first season of a given branch's life. 

 

The two kinds of "showy-barkers" receive opposite handling to emphasize their displays.  The trunk of Platanus is the showiest portion of the entire tree, and younger growth may well be cut off to display the trunk more fully.  The trunks of trees with showy younger growth is non-descript, and can be prevented from forming at all by pruning the tree down to the stumps of lower growth each Spring—a practice known as coppicing—to stimulate all possible new growth.

 

Although Platanus can also be pollarded, and produces lush new growth as a result—see "How to handle it:  Another option—or two!" below—the goal of Platanus pollarding isn't to enhance the display of colorful new bark at all.  The bark on new twigs isn't notably colorful.  Instead, the goal is to control overall size while also producing a distinct pattern of dense new growth and a showy (if eccentric) overall form that is, happily, also a stronger contrast with the foliage-free trunk than the looser and larger foliage display of the free-range canopy.

 

Some other species and cultivars of Acer, as well as some forms of Lagerstroemia, Betulus, Clethra, Pinus, and Stewartia, also produce showy bark only on their trunks and their older limbs; mild-climate plants with showy-in-maturity bark include species and cultivars of Arbutus, Eucalyptus, and Cinnamomum

 

its tolerance of habitat:  Planetrees are legendary for surviving in mediocre or downright hostile circumstances, such as along the streets and in the parks of cities. 

 

its flexibility:  Like another of the most massive hardy trees that is, also, usually grown as a free-range monster—beeches—planetrees are equally easy-going about being pruned.  They resprout quickly, and even lustily, so are a prime candidate for pollarding as well as for pruning into large-scale hedges.      

Flowering season

Early Spring, before the leaves emerge.  The apetalous flowers are prickly "gumball" spheres, and are not very showy.

Color combinations

The bark of 'Suttneri' is white and cream and tan; the foliage is pale to light green or, ephemerally in Spring, white to palest pink.  Could the tree be planted in a garden with colors exclusively of cupcake frosting: White, mint-green, creamy pink?  If ever a tree were made for a life amid pastels, 'Suttneri' is it.

Partner plants

With its potential for spectacular bark that begins, literally, at ground level, 'Suttneri' is a great candidate for minimal as well as low underplanting.  Because the bark is most fully revealed during the cold months, when the tree is leafless, an evergreen underplanting will handle the challenge of covering the ground during months when your gaze will be led directly to it.  If possible, avoid evergreen groundcovers that are opportunistic climbers, such as ivy or euonymus, which would need to be kept pruned off of the tree's trunk.  If you establish it at the same time you plant the Platanus, Sarcococca humilis would be ideal.   

 

Enhance the show of the creamy bark higher up by backing the tree with evergreens.  Unless the tree is planted in front of older, taller, already-established evergreens—and with plenty of space between the two, so the growing tree doesn't shade the evergreens and thin their growth—an evergreen backdrop would be difficult to establish for a tree that has the potential to quickly become fifty feet tall and wide or even larger.  See "How to handle it: Another option—or two!" for several strategies to control the size of 'Suttneri', which makes an evergreen backdrop all the more quick to achieve and practical to maintain. 

 

Taller partner plants beneath the canopy of 'Suttneri' can also be added as long as they aren't sited close enough to the trunk to obscure it.  Because almost any other deciduous plant is going to look second-best near a tree with near-white bark, evergreen partners are best here, too.  With evergreen underplanting, backgrounding, and larger-scale ornamenting, the three kinds of evergreens will need careful coordination if they aren't to seem repetitious.  If the evergreen groundcover is broadleaf (such as sarcococca), make a shrubby partner coniferous (such as mounding or upright plum yews), and the background one of the fan-spray conifers such as Arborvitae or Chamaecyparis.  If the background is an evergreen climber (such as ivy), try prostrate plum yews as the evergreen groundcover, and a dramatically-foliaged broadleaf as the ornament:  Mahonia bealei, say, or if you're gardening  in Zone 7 and warmer, Sabal minor

 

Only when the Winter display of the plane tree has been fully "accessorized" with evergreens is it worthwhile considering whether a warm-weather plant partner is also needed.  The large maple-like foliage of plane trees ("acerifolia" is literal Latin for maple-leaved: Acer (maple) + foliage) would be even more exciting with a happy colony of some big fern or other enjoying the tree's shade.  And the ferns would also be at home in the same rich and well-watered soil the planetree craves.  

Where to use it in your garden

'Suttneri' is a striking tree if growing free-range as well as when trained (see below for options), so locate the tree where its performance receives the setting it deserves.  A free-range specimen growing in the middle of a large lawn can be as telling as a beech.  Growing in a courtyard, it's tall enough to shade nearby buildings while also meriting appreciative views from all of their windows. 

 

Given the relative compactness of a pollarded specimen, plus its intense juxtaposition of white trunk topped by a dense leafy canopy, the ultimate choice is to site 'Suttneri' as a living sculpture, with a green backdrop and base.  Could a quartet of pollarded trees be growing in a rectangle of prostrate plum yews?  Or lining a driveway that runs near a brick building onto which ivy can grow?  For my money, heaven is the opportunity to site a plant that is distinctive, all on its own, and then train it into a display that is a unique partnership of plant and gardener.

Culture

Full sun.  Despite the tree's ability to survive in just about anything, strongest and fastest growth is in deep rich soil that never lacks for water.  Platanus grows naturally along bottomland—flat alluvial terrain alongside streams, where occasional Spring flooding is the norm.  With its flat terrain, full sun, high water table, and thick soil, my garden is any planetree's dream.

How to handle it: The Basics

Plant in Spring, providing enough water for the tree to establish its first season.  In its preferred habitat—see "Culture" above—Platanus is self-sustaining thereafter. 

How to handle it: Another option—or two!

Platanus species and cultivars are classic subjects for pollarding, because the trees branch quickly as well as profusely in response to such vigorous pruning.  Because the resultant growth of plants that are pollarded or coppiced is, so often, faster or more colorful (in leaf and/or bark) or with larger leaves than free-range growth, it's always worthwhile to pollard trees whose free-range growth already has one or more of those qualities, in hopes that the growth from pollarding will (as is often the case) display them in spades.  'Suttneri' is a prime pollarding candidate because of the variegation of mature foliage, the ephemeral coloring of the juvenile foliage, and because the pollarding can reduce the size of the tree canopy, as well as simplify its geometry, both of which will draw attention to the "quickly-creaming" bark of the trunk. 

 

There are four schools of pollarding to consider.  In the first, you cut back all young growth in late Winter, to a single point at the top of a shortish trunk.  (How tall, or rather, short?  You need to be able to do your pruning from a stepladder, and not one of heroic proportion.  A trunk eight or ten feet tall is plenty tall.)  This creates the smallest canopy—from four to six feet across, usually—with all new growth arising from just the one central point.   

 

In the second, you allow some branches to develop, and pollard to the tips of each.  This creates a broader canopy—a higher one too, if you allow branches to grow upward before pollarding, not just outward. 

 

In the third, young branches are trained outward along a frame of horizontal bamboo poles, to create a flat canopy of growth.  The tree is pollarded by pruning side branches back to stubs all along this scaffolding of horizontal limbs, to ensure that higher-elevation twigs are never more than a season old, as well as to control further lateral growth of the canopy.

 

In the fourth, those same horizontal bamboo poles are tied to vertical supports, creating a flat vertical frame to which young branches are tied.  Side branches and out-of-bound vertical branches are pruned off each Spring, creating a vertical screen of growth, i.e., a planetree espalier. 

 

With both of the bamboo-pole training methods, the young planetree limbs soon become thick enough to be self-supporting.  Unlike espaliered lindens, which typically remain supported by permanent metal and wire frames, espaliered planetrees can be free-standing.

 

I'm going to try the third option, creating a horizontal canopy of growth a fraction the spread of one that's free-range.  The foliage of pollarded planetrees is born more densely, because the pruning results in more and more closely-spaced twigs.  The solid block of foliage of a pollarded 'Suttneri' planetree should be an even more intense contrast with the shocking white trunk than the free-range canopy, which can be open and, therefore, gradual in the change from trunk to trunk-with-major-limbs to major-limbs-with-branches-and-some-leaves to branches-and-twigs-that-all-have-leaves. With the pollard, the tree is only trunk, until, all of a sudden, it's all leaves and twigs.

 

A pollarded planetree has yet another appealing characteristic:  The pollarding should be done in Winter, when the tree and the wider landscape both are still quite dormant.  This helps reduce the likelihood of introducing anthracnose into the tree in warmer weather, via the numerous cut ends of twigs and branches that have become active for the season.  Pollarding is a terrific project for cold and even snowy weather.  The leaves are off the tree, so you can see just what you're doing.  And unlike low-to-the-ground pruning, the snow will never be so high that it covers where you need to be pollarding.  I find that I can prune even in heavy cold-weather clothing, too.  Pollarding requires none of the finger-to-finger dexterity of weeding, where you need to be selecting this sprig and this blade, not that; or espaliering, where you need to be tying this twig here, and in tight quarters, not there. 

 

And if the weather is merely cold and rainy, pollarding is still the chore of choice.  You don't have to work kneeling in mud, when, in any event, you'd be compacting the soil, always a no-no.  Instead, you pollard, up on your step ladder, with your knees out of the mud and the rest of you snug in your rain gear. 

Quirks or special cases

None.

Downsides

As long as 'Suttneri' enjoys reasonable soil and moisture, as well as full sun, it is a tolerant and enduring tree.

Variants

Platanus x acerifolia cultivars are of interest primarily for greater resistance to mildew and anthracnose, although there is also preference for exfoliating bark.  P. x acerifolia is fairly resistant to anthracnose thanks to its P. orientalis parent; P. occidentalis is highly susceptible, especially if growing outside its favored bottomland habitat.  'Bloodgood' is less resistant than 'Yarwood'.  'Exclamation' is resistant as well as hardier, to zone 4.  'Mirkovec' is on my wish-list, with a shrubby habit and narrow-lobed leaves variegated in pink, cream, and bronze.

Availability

On-line and, sometimes, at destination nurseries.

Propagation

By grafting.

Native habitat

Platanus x acerifolia is a hybrid of Platanus orientalis, native from the Balkans to Iran, and Platanus occidentalis, broadly native to eastern North America.  The tree was first noticed in London in 1663, as a naturally-occurring hybrid.

 
 
FacebookTwitterRSS Feed

Stay in touch!

 

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

 

* indicates required