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 Southern Catalpa

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Such wild foliage!  With just a slender centerline of green, the pale leaves of variegated catalpa are—at least for a month or two—one of the brightest things in the whole garden.  With so little chlorophyll showing, it's hard to believe the tree can produce enough energy to grow. 

 

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The splotch of chlorophyll is center-line but quite irregular.  As the weather warms, more and more of the leaf is given over to chlorophyll.  Conceivably, this means that the tree doesn't reach full horse-power until Summer, when the foliage is almost all green.

 

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In Spring and early Summer, the thin strips of chlorophyll aren't visible from any distance. 

 

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The entire tree is shimmering gold.

 

Here's how to grow this rare ornamental tree:

 

Latin Name

Catalpa bignonioides 'Variegata'

Common Name

Variegated catalpa

Family

Bignoniaceae, the Trumpet Vine family.

What kind of plant is it?

Deciduous tree.

Hardiness

Zones 5 - 9.

Habit

Single-trunked but shrubby and open, especially in youth and adolescence.  Taller than wide, sometimes not by much.

Rate of Growth

Medium.

Size in ten years

Ten to twelve feet tall, eight to ten feet wide.  Ultimately, not much taller than fifteen feet.  'Variegata' is less than half the size of either the straight species of C. bignonioides or its solid-yellow cultivar 'Aurea', both of which mature to full-sized shade trees.

Texture

Despite the large leaves, the canopy is not dense, because the whorls of foliage arise only at the tips of the branches.

Grown for

its foliage:  Variable: four to ten inches long, three to eight inches wide.  As is typical for Catalpa, emerging leaves are darker, but only faintly tan in the case of 'Variegata.'  (Youngest foliage of Catalpa b. 'Aurea' is unquestionably tan; that of C. x erubescens 'Purpurea' is a strikingly deep burgundy.)  They soon progress to a pale greenish-yellow with only a narrow irregular band of chlorophyll lengthwise down the leaf center.  The amount of chlorophyll increases steadily, and by mid-Summer most of the variegation is lost.

 

its flowers: Catalpa flowers are a show in themselves.  Those of C. bignonioides are white overall, with small blotches of purple and yellow that are only evident when seen up-close.  As is typical for the Bignoniaceae family, the flowers are foxglove-shaped.  They  are prominent, and for three reasons:  They are held erect, like the panicles of chestnut flowers.  They emerge after the Spring crush of bloom from other ornamental trees, such as dogwoods and fruit trees.  They emerge after the tree's foliage is fully formed, and so enjoy a leafy backdrop.

Flowering season

Mid-to-late June in New England; earlier further south.

Color combinations

The bright yellow foliage is even more vivid near dark green.  If either saturated and deep blue or burgundy is nearby, even better.  Pale colors of any hue are likely to be overpowered.  At first glance, yellow might seem a natural, but is more likely to be competitive:  The yellow of 'Variegata' or that of the partner plant is likely to look weaker in comparison to the other.

Partner plants

Because the growth of 'Variegata' tends to be open, a backdrop of foliage is needed if you're not to look right through the tree.  With its bright foliage, even mid-green of surrounding woods will look dark by comparison.  But if ever there were a plant to site to the front of the dark hulk of a large yew, this is it. 

 

The tiny foliage of any conifer, as well as that of small-leaved deciduous and broadleaved evergreen species, provides contrast from shape alone, especially if you choose to keep your 'Variegata' to the size of a shrub.  In addition to yews, consider plum yews, azaleas, boxwood, and Japanese holly.  The leaves of typical rhododendrons are too similar in shape and size to those of 'Variegata'.  

 

Flowering partners that could provide deep blue or burgundy (or, not too far a stretch, velvet red) at the same time that the foliage of 'Variegata' is at its brightest include Calycanthus floridus, Clematis recta 'Midnight Masquerade'.  The pairing is even stronger if the partner climbs, or at least sprawls, and so can be lead up into the 'Variegata' canopy if it's low enough.  The flowers of Rosa 'Souvenir du Doctor Jamain' are an exceptionally deep plum, and retain their color best with some shade.  Site this climber to the north of 'Variegata'.  Alternatively, you could grow one of the Group C clematis, which would normally be cut down to lowest buds to delay flowering until high Summer.  Unpruned, they can start into bloom in June.  Clematis 'Rooguchi' could climb through branches of a low-to-the-ground Catalpa pollard; its flowers are a steely blue, and the buds, even more thrilling, are purple so dark it verges on ebony.  Although there are plenty of large-flowered clematis that are happy to explode into blue bloom in June, their flowers' size and long petals are, to my eye, too similar in scale and shape to the foliage of 'Variegata'.

 

If there's still room beneath, behind, or amid the foliage of 'Variegata', you could introduce plants whose late-season interest will combine with Catalpa foliage that, by the time the weather is truly hot, is barely distinguishable from the run-of-the-mill green of the straight species.  The trunk of 'Variegata' could be the support for yellow Campsis.  If its laterals were pruned off—do this in late Winter, when you might be pruning the Catalpa itself—the new growth would grow out to the perimeter of the Catalpa just in time to flower.  I suggest using C. radicans 'Flava', whose clusters of yellow flowers in August into September look like hands of miniature bananas. 

Where to use it in your garden

'Variegata' is such a flashy plant in Spring and early Summer—and such a rarity—that the temptation is to use it as a major focal point.  But by July, by which time the foliage is usually all-green, you and your garden's visitors may wonder what the fuss is about.  You might be able to ensure continued "star quality" by partnering with plants with late-season interest, but it's easier to give 'Variegata' a location that's not more than secondarily prominent.  Then you can enjoy it in May and June, and won't be disappointed in its comparative blandness from July on.

Culture

Full sun, in any reasonable soil and drainage.  Growth is fastest and fullest in soil rich in organic matter.  Catalpa could never be described as picky, but does thank you for considerate siting.

How to handle it: The Basics

Plant in Spring; provide enough water for the tree to establish its first season.  When growing in any normal soil, established Catalpa trees are self-reliant, tolerating high heat as well as humidity. 

 

'Variegata' doesn't need formative pruning if you're growing it as a full-sized tree.  See "How to handle it: Another option—or two!" below for another possibility.

How to handle it: Another option—or two!

Catalpa 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. 

 

The growth rate of 'Variegata' is slower, so it could the exception that proves the rule.  In Spring of 2013, I'll subject mine to moderate pruning to test its response.  If the resultant growth has typical Catalpa speed and profusion, more extensive pruning—even outright pollarding—could be the next step.  

 

There are four schools of thought for pollarding Catalpa species and cultivars.  In the first, you cut back all young growth in late Winter, to a single point at the top of a shortish trunk.  This creates the smallest canopy, from four to six feet across, usually, with all new growth arising from just the one central point.

 

How tall a trunk—or rather, short?  It's easiest to pollard when you're standing on the ground, in which case the trunk shouldn't be higher than five or six feet.  It's easy to pollard when using a stepladder, which permits a slightly higher trunk.  Even so, eight or ten feet tall is plenty.  You also might want to consider pollarding to a trunk that is only a couple of feet tall, which results in a "tree" of only shrub-like dimensions.  This low-elevation pollarding brings the foliage down to a more accessible level for partnering with contrasting underplantings, or maybe even a vine or scandent shrub that can grow up into the Catalpa canopy.  See "Partner Plants" above.

  

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 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, and to control further later growth of the canopy.

 

In the fourth, the horizontal training poles are tied to a vertical frame that is, itself, made of more bamboo poles.  Side branches and out-of-bounds vertical branches are pruned off each Spring, creating a vertical screen of growth, i.e., a Catalpa espalier. 

 

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

 

A pollarded Catalpa has yet another appealing characteristic:  The pollarding can be done in Winter, when the tree and the wider landscape both are still quite dormant.  Indeed, pollarding is a terrific project for a season when the weather cold and even snowy.  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 while up on your step ladder, with your knees out of the mud and the rest of you snug in your rain gear.

 

Yet another option is to pollard 'Variegata' to a very low trunk

Quirks or special cases

Catalpa bignonioides is one of the few trees that can be sold bare-root even when large enough that the trunks are several inches thick.  Many years ago, I purchased a shipment of standards of 'Nana' directly from a nursery in Ontario, Canada.  The 18-wheeler truck arrived, and I could unload the trees two at a time, one in each hand.  Planted and watered, they promptly burst into leaf.  You're unlikely to find any vendor growing large enough stock of 'Variegata' to consider selling it this way. 

Downsides

The foliage coloring calms down considerably in the heat of Summer.  Mildew can occur later in Summer.

Variants

The straight species of Catalpa bignonioides is garden-worthy in itself, but is widely naturalized over much of North America.  Because there's probably one growing near you already, choose one of the cultivars for your own garden.  The foliage of 'Aurea' is bright yellow in Spring, and mutes in Summer heat.  C. x erubescens 'Purpurea' is a hybrid of C. bignonioides and C. ovata; its new foliage is a startling near-black, and its flowers are white and pink.  The foliage of 'Nana' is plain green; its habit is semi-dwarf.  'Nana' is usually seen grafted atop the trunk of the straight species of C. bignonioides to form a standard. 

Availability

On-line and, very rarely, at retail rare-plant specialists.

Propagation

By cuttings.

Native habitat

Catalpa bignonioides is native to southeastern North America, from Alabama to Florida.

 
 
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