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 Hardy Clerodendrum

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Such bright foliage!  Variegated hardy clerodendrum puts on a high-energy show all season long.  And then, in late Summer, it ramps up still further, by bursting into bloom.

 

The show of the foliage is anything but static.  The youngest leaves show only modest coloring, but by the time they have expanded, their broad irregular margins have become bright yellow.

 

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By the time the next new pair of leaves has emerged, those yellow-margined leaves have changed yet again.  The yellow  becomes creamy white, and swathes of the remaining green center turn slate-gray. 

 

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In my experience, Clerodendrum trichotomum 'Variegata' isn't as floriferous as the straight species.  I'm providing attentive watering and fertilizing this season, in hopes that my 'Variegata', which I keep in a container, will favor us with panicles of jasmine-fragrant white flowers in August and September.

 

 

Here's how to grow this extraordinarily showy shrub:


Latin name

Clerodendrum trichotomum 'Variegata'

Common name

Variegated hardy clerodendrum

Family

Lamiaceae, the mint family.

What kind of plant is it

Deciduous shrub.

Hardiness

Zones 6 (with protection) to 9.

Habit

Usually multistemmed and suckering from the roots, like sumac or sassafras.

Rate of growth

Medium—slower than the straight species.

Size in ten years

If growing free-range and in Zone 8 and warmer, a colony that grows to six to ten feet tall and eight to twelve feet wide.  Much smaller in colder climates; at the limits of hardiness (the cold end of Zone 7 into the warm edge of Zone 6), a die-back shrub or even a returning perennial.  See "How to handle it" below for strategies to enhance hardiness.

Texture

Variable.  My bush is open and graceful, but in milder climates, where 'Variegata' can grow unfettered, the texture is likely to be full and even heavy, if somewhat lightened by the bright foliage. 

Grown for

its flowers: White and fragrant, tubular at the base but opening to an inch or so wide.  In cymes that are six to nine inches across.  A bush in heavy flower can perfume the whole garden; the fragrance is sweet and jasmine-like.

 

its fruit:  The flowers mature to small but spectacular blue berries, while the reddish calyx backing each flower opens wide, creating a display of what looks like burgundy petals.  The show of Clerodendrum trichotomum in fruit is as engaging as when the shrub is in flower, and extends the shrub's peak season into October.   

 

its foliage, which is strongly margined and sectored with color: Yellow as soon as a leaf has unfurled, lightening to creamy white soon thereafter.  The leaf's irregular central portion of green becomes clearly variegated, in itself, with large sections becoming a pronounced gray-green.  In pattern as well as palette, and even in overall size, the foliage of variegated hardy clerodendrum is similar to that of variegated Persian ivy.  Provided the bush is not drought-stressed, the foliage does not scorch in full sun, although the intensity of the variegation diminishes as Summer progresses. 

 

its vigor: Although 'Variegata' is slower than the straight species, this is still a shrub that grows eagerly, and welcomes the sustained heat of Summer that can make other "woodies" look tired.  Given full sun and nutritious well-draining soil, plants recover quickly from Winter damage, and seem to flower with unimpaired vigor.

 

its late-Summer peaks, of flowers and then fruit:  Hardy clerodendrum peaks when many gardens may have little other than hydrangeas and dahlias in bloom.  The fragrance of the flowers is a further seasonal bonus, and the startling blue fruit that follow a joyful surprise for first-time viewers.

 

its imperviousness to browsers:  When bruised, the foliage emits the strong fragrance of peanut butter.  Despite the reality that browsing animals are, in part or in whole, vegetarian, peanuts and peanut butter aren't appealing to them.  Deer leave hardy clerodendrum strictly alone.  Other forms of Clerodendrum are, typically, similarly impervious.

Flowering season

High Summer: Late July into September here in New England.  New flowers can still emerge while earlier ones have matured to fruit. 

Color combinations

Although each leaf is its own individual combination of cream, gray, yellow, and pale green, collectively, the foliage centers on cream and yellow.  While this color could, theoretically at least, accompany almost any hue, hot or cool, saturated or pastel, it's easier to juxtapose with a single saturated color.  Burgundy, pink, red, deep blue, chrome yellow, or orange would all be exciting as the colors of the foliage or flower of partner plants.

Partner plants

Variegated hardy clerodendrum benefits from similar partnering strategies as variegated Persian ivy.  Both are so interesting in detail, and usually so prominent in overall size, that partner plants need to be simple as well as substantial if they're not to be overwhelmed.  Ferny or grassy foliage would always be welcome, so partner with, say, a purple-leaved Japanese maple rather than a purple-leaved smokebush.  And, whenever possible, partner with true ferns.  Because the foliage of both the ivy and the clerodendrum is relatively large, it would be difficult to combine with the standard broadleaves—rhododendrons, camellias, hollies, and pieris—without the effect being heavy and static.  The exception would be if the foliage of the partner plant were truly huge.  My 'Variegata' is next to a trio of Chinese tulip trees, Liriodendron chinense, kept pruned as large informal shrubs.  Their foliage is ten times as large. 

 

But only one or two neighboring plants can have such huge leaves if the overall effect isn't to be leaden.  For the rest, choose grassy, deciduous, and herbaceous partners.  Bamboos in the Fargesia genus have the smallest leaves of such "woody grasses."  Nandina domestica has ferny foliage, as do the sambucus cultivars with dissected leaves.  The foliage of cut-leaf alder, Alnus glutinosa 'Imperialis', is as ferny as that of any Japanese maple.

Where to use it in your garden

Variegated hardy clerodendrum is exceptionally showy in the warm months—and quite bland in the cold ones.  Site it where you'd like to draw attention in the Summer, but also where you don't have to look at it during the Winter.

Culture

Full sun in any decent well-draining soil and site.  Excellent drainage is essential for maximal hardiness at the cold end of this plant's range, let alone when attempting to establish it in even colder spots.

How to handle it: The Basics

In Zone 8 and warmer, plant in Spring or Fall, and take care to provide enough supplemental water to enable easy establishment.  In Zone 7 and colder, plant only in Spring. 

 

Where soundly hardy—in Zone 7 and warmer—Clerodendrum trichotomum sprouts directly from the roots with such vigor that the colony will need to be sited with the same forethought and ongoing care as bamboo.  Ideal siting would be in a bed backed by walls or ledge, and fronted by asphalt or concrete paving.  Or be planted, all by itself, in a bed surrounded by a wide apron of grass that is mown regularly.  Otherwise, plan on edging all around the colony with a flat-edged shovel, just as you would do for a colony of Xanthorhiza.  

 

In Zone 7 and colder, the colony will need the same annual Spring grooming that you'd give to traditional mop-head hydrangeas.  With the Clerodendrum, as well, let the Spring reawakening of the bush provide guidance for where to cut, and when: Wait until the expanding buds and emerging foliage of the viable portions of the branches show clearly where to cut to remove the leafless dead tips farther up.

 

If your goal is to establish variegated hardy clerodendrum where it might not, in truth, be fully hardy, planting in an exceptionally well-drained location is essential.  Add sand and gravel to otherwise rich soil, in a location that's part of a larger slope, ideally a foot or two above the adjacent bed, pathway, or lawn, so that surface water drains away promptly.  In addition, choose a location that faces south or west, so the bush enjoys all possible heat and sun during the growing season, and therefore ripens its wood thoroughly.  Wait until the foliage has dropped after early Fall frosts, so you can mulch more easily around the base of the stems.  If the shrub's location is practical, and your back strong, you could even "mulch" with shovels of soil, mounding up, over, and around the base of the bush the way that you'd do when overwintering fig trees that are grown in-ground as die-back shrubs, not small trees.  Even so, substantial die-back of exposed branches is to be expected.  As long as your Summer is warm, and you ensure that the bush receives any needed watering and fertilizing, it will resprout promptly, and be in flower by Labor Day.

 

Although my bush is stable, twigs of 'Variegata' are reported as producing shoots with all-green foliage.  Should that happen, prune out those reversions promptly lest they overgrow the variegated part.  Leaves are variegated because those portions lack the chlorophyll that would tint them green—and hence, also, provide the ability to synthesize carbohydrates.  The stunning appearance of the variegated leaves, then, is the direct result of their diminished ability as energy producers.  Branches that have only variegated leaves are slower growing than those whose leaves have their full complement of chlorophyll.  Variegated plants are often somewhat smaller overall than their unvariegated brethren, too.

How to handle it: Another option—or two?

Clerodendrum trichotomum can be grown in a large container.  Moved into shelter after the shrub has lost its leaves for the cold season, there's no danger of Winter die-back.  Brought out into the garden in Spring, the containered rootball will warm up faster than the ground, and so helps the shrub revive all the more quickly. 

 

With its large leaves, profuse foliage, and quick growth, hardy clerodendrum will need careful watering and generous fertilizing to keep it in unfettered growth all season.  As with all late-season flowerers, there's the potential for blooms at the tip of every new stem.  Perhaps this season I'll finally get going on a supply of "manure tea," by sinking a burlap bag of horse manure in the thirty-gallon galvanized can that serves as my dipping pond for the watering can.  You could also use water that's beefed up with fish emulsion, or even generic blue-granule plant food.

 

Consider sinking the container halfway into the ground for the Summer, in hopes that clerodendrum roots will grow out through its drainage holes into the surrounding bed.  This lessens but doesn't eliminate the need for supplemental watering and fertilizing.  

 

After mild frosts have killed the leaves—alas, there's no Fall color—dig up the pot and move the plant into cool but frost-free shelter.  I lug mine down to the basement, where it and dozens of other deciduous containered plants snooze, in the humid dark, from late October to mid-April.  If you have the room, move the shrub into shelter before frost, to keep it in leaf, and growth, over the Winter.  Space is at such a premium in my greenhouse that I'm grateful when any tender plant can become deciduous and overwinter in the basement.

Any (other) quirks or special cases?

None.

Downsides

If only "hardy" clerodendrum were hardier, still. 

 

I've established several thriving colonies here in New England, and I'm not aware of self-seeding despite heavy production of the showy blue fruits.  If possible, check with other gardeners in your area—or with your local office of the USDA Cooperative Extension Service—to see if this or other Clerodendrum species are not recommended for your area.  C. indicum and C. bungei are classed as invasive in Florida, but their method of spread is listed as their stoloniferous roots, not by seed.

Variants

Depending on how they are classified botanically, there are anywhere from 150 to 450 species of Clerodendrum, from vines and shrubs to trees, one species of which, C. floribundum, can grow to eighty feet and higher.  Large clusters of showy and, often, fragrant flowers over a long period of time are typical.  A few species—C. paniculatum, C. ugandense, C. splendens, C. bungei, C. incisum, C. quadriloculare, C. thompsoniae—are as unavoidable in subtropical and tropical gardens as rhododendrons are in temperate ones, and are essential "wow!" plantings to thrill Northern visitors to warm-climate resorts.  Their spectacular clusters of fragrant flowers suggest common names such as "winter starburst," "cashmere bouquet," "flaming glorybower," and "champagne clerodendrum"—which vividly capture these plants' appeal. 

 

Although most Clerodendrum species are evergreen when growing in mild-enough climates, it's not unusual for them to become deciduous in somewhat colder habitat.  Additionally, many sprout directly from the roots.  Although this results in colonies whose outward spread can be difficult to control in mild climates, it enables quick regrowth in colder ones.  Flowering is at the tips of new growth, so forms that can be grown as such "returning perennials" still have the potential to flower each season.  Forms with potential for the deciduous lifestyle, let alone that of a returning perennial, can also be grown in containers that are Summered in the garden, and sheltered leafless and dormant in the Winter.

 

My wish-list for these containered possibilities include C. indicum and C. paniculatum, especially in its hard-to-find cultivar with purple leaves, 'Borneo Sunset'.

 

Alas, Clerodendrum trichotomum is one of very few forms of Clerodendron that are hardier than Zone 8, let alone Zone 7, so its common name—"hardy clerodendrum"—does not overlook a lot of other worthy candidates.  C. trichotomum itself is highly garden-worthy, being more securely hardy into Zone 6 than 'Variegatum'.  In my experience, it's more floriferous, too.  'Golden Glory' has gold foliage in Spring; 'Purple Haze' as foliage that is flushed purple.  'Carnival' is probably the same as 'Variegata'.

 

The foliage and flowers of C. trichotomum var. fargesii are the same as those of the straight species, but this cultivar is reputed to be even hardier, as well as even more stoloniferous.  I'm growing fargesii, and, believe me, in my too-rich soil and too-flat terrain, even this hardiest of the hardy clerodendrums is still not going gangbusters.  The real problem may be that this cultivar has also been reported to be a shy flowerer even in the best of circumstances.  I'll replace it with the straight species next Spring. 

Availability

On-line.

Propagation

By softwood cuttings in Summer, and by digging out rooted shoots from the mother colony in early Spring.

Native habitat

Clerodendrum trichotomum is native to China and Japan.    

 
 
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