A Gardening Journal

Variegated Southern Sweetbay Magnolia

Magnolia-virginiana-var.-australis-Mardi-Gras-fingers-foliage-122114-640

 

Here it is: The only magnolia with kick-ass variegation. Better yet, leaves of 'Mardi Gras' are evergreen. Better yet, the tree can shed them if the Winter gets too rough. Best of all, the resultant show of bare twigs—green-barked, mind you—would be more striking for this magnolia, even, than its flashy leaves.

 

And, yes, the tree flowers, too. Mine is too young but, perhaps, in three years? Then lemon-fragrant white blossoms could begin to form at the tips of the stems.

 

Magnolia-virginiana-var.-australis-Mardi-Gras-foliage-122114-640

 

Even so, the foliage is the thing. All magnolias flower and, often, spectacularly. A magnolia with variegated foliage? Despite there being hundreds of Magnolia species and thousands of cultivars, the exuberant and even defiant variegation of Magnolia virginiana var. australis 'Mardi Gras' is unique. 

 

Magnolia-virginiana-var.-australis-Mardi-Gras-overall-122114-640

 

As showy as the foliage is during the Summer, Winter is its peak. This is somewhat by default, in that so many other plants lose their leaves entirely during the cold months. At first, then, it can seem quite the bummer that if the weather is really severe, 'Mardi Gras' sheds its foliage, too.

 

Magnolia-virginiana-var.-australis-Mardi-Gras-for-stems-detail-122114-640

 

But not when you notice the young twigs: Their bark is bright green. If the leaves were gone, the twigs would be center-stage. Handily, there's a way to make their performance sing. Read on! 

 

Here's how to grow this uniquely showy tree:

Latin Name

Magnolia virginiana var. australis 'Mardi Gras', also marketed as 'Mattie Mae Smith'

Common Name

Variegated southern sweetbay magnolia

Family

Magnoliaceae, the Magnolia family.

What kind of plant is it?

Small tree with foliage that, depending on the severity of the Winter, can be evergreen, semi-evergreen, or fully deciduous.

Hardiness

Magnolia virginiana is reliably hardy from Zone 5 to 9, but will be fully deciduous in Zone 5, and might also suffer some die-back. Sources vary about the hardiness of the variety australis: from Zones 5 - 9 to Zone 8 - 9. Considering that there's frequent-enough mention that the variety australis is less hardy than the straight species, I recommend that 'Mardi Gras' be considered hardy only as cold as Zone 6. In addition, its extraordinary foliage is all the more striking into the winter, when so many neighboring plants are likely to have become leafless or have died back to the ground. So it makes sense to grow 'Mardi Gras' in such a way that its foliage stays in good shape for as long as possible.

 

See "How to handle it: Another option—or two!" for siting and handling strategies that prolong foliage retention as well as minimize damage. 

Habit

Upright; often multi-stemmed and open. In Zone 7 and warmer, could probably grow large enough to function as a small ornamental tree. In Zone 6, more likely to be shrubby or even suckering. 

 

In any climate, habit also depends on exposure: Trees growing in full sun can become broad, dense, and foliaged nearly to the ground. With increasing shade, growth is narrower and much more open, with plenty of trunk and branches exposed.

Rate of Growth

Medium at best: Because so much of each leaf's area lacks chlorophyll, 'Mardi Gras' grows more slowly than Magnolia virginiana var. australis itself. 

Size in ten years

Mature size as well as rate of growth can depend on the climate. Magnolia virginiana itself isn't likely ever to exceed twenty feet tall or wide in Massachusetts, but could top sixty feet in Mississippi. Although the variety australis is thought to mature as a larger and more fully evergreen tree, this would likely be evident only in its Deep South home range. Farther north, it is likely to be shorter than the more hardy straight species of Magnolia virginiana.

 

On account of both its extensive variegation (which reduces the portion of each leaf that is pulling its own weight in terms of photosynthesis) and its origin from the variety australis (which is often listed as a full zone less hardy), 'Mardi Gras' is unlikely ever to exceed ten to fifteen feet high or wide in Zone 6. Possibly to twenty feet high in Zone 8 and warmer. This cultivar wasn't discovered until 1995, so its ultimate height in any climate may not yet be known.

Texture

Unless growing in full sun, where the texture can become dense and even heavy, this magnolia is usually open, even loose, with plenty of main branches and even secondary stems exposed. See the second "How to handle it" box for suggestions on increasing both density and compactness.

Grown for

its leaves, which are narrow, smooth-edged, pointed, and three to five inches long. Their lower surfaces are silvery, and even a light breeze can ruffle the foliage enough to create a flashing display. In the species, the upper leaf surface is a solid and shiny dark green. 'Mardi Gras' retains that green only in an irregular central blotch; in a sharp and striking contrast, the entire perimeter is bright yellow. The proportion of yellow to green varies leaf to leaf, but it isn't unusual for yellow to predominate.

 

The origin of the "sweetbay" common name is puzzling. When bruised or crushed, the foliages releases odors that might remind you of those of true bay, Laurus nobilis: spicy and musty—anything but sweet. The "sweet" portion of the name, then, probably refers to the fragrance of the Magnolia virginiana flowers; the "bay" portion to the leathery, evergreen, and similarly-shaped Laurus nobilis foliage. I'm unable to find a reference to any fragrance of Laurus nobilis flowers, which would seem to further affirm the appeal of any "bay" whose flowers are sweet.

 

its flowers: These are creamy white with a lemon fragrance, and emerge at the very tips of young stems. They are only two to three inches across—the smallest of any magnolia native to North America—and, so, aren't nearly as showy amid the bright drama of the variegated leaves of 'Mardi Gras' as when backed by the dark green leaves of the straight species. (The flowers of the species aren't that showy, even so, because they are sporadic and small.) Regardless of their modest visual impact, Magnolia virginiana flowers are prized for their fragrance, which one gardener describes as being so penetrating and intense it overwhelms the scent of her nearby roses.  

 

its seeds: These are large and bright red, borne in short dense clusters arising from a dark red cone-like base. Unlike the seeds of Magnolia grandiflora—which are extruded gradually from a "cone" so much larger that, despite the seeds' size, they are always displayed individually and, therefore, to less effect—seeds of Magnolia virginiana and its variety australis usually emerge en masse, with little cone showing between them. Their display can be as noticeable or even more so than that of the flowers.

 

the shiny green bark of its younger stems and branches: Besides being notable simply for being green instead of one of the more usual and bland bark colors like beige or brown or gray, young bark of Magnolia virginiana is doubly distinctive in being a noticeably lighter shade of green than the central green patch of the leaves. Trunks and older branches display mature bark, which is still smooth (although no longer shiny), and a less interesting light gray. See the second "How to handle it" box for an experiment for growing this tree in Zone 6 and the colder reaches of Zone 7. There, the tree becomes fully deciduous as Winter wears on. Strategic siting and well-timed pruning should increase the proportion and density of young twigs and, therefore, enhance the Winter and early-Spring display of the leafless green stems.

Flowering and seed-display seasons

Dependent on the climate. In Zone 7 and warmer, scattered flowers can appear steadily from Spring to frost. In Zone 6, most of the flowers emerge in May and June, but further scattered blooms could emerge in July and even August. In any climate, seeds tend to begin emerging in August.  

Color combinations

On their own, the white flowers and dark green of the leaves of 'Mardi Gras' go with anything; it's the distinctive and prominent butter-yellow variegation of the leaves that can suggest colors of neighboring plants. Almost any shade of yellow or green would be a no-brainer, as would burgundy or blue or pink, especially if neighboring plants also featured a yellow detail themselves. I've taken my own advice in that regard, and have sited 'Mardi Gras' near a group of 'Altissimo' roses, whose single flowers have prominent yellow stamens. Their petals are bittersweet red—proving that 'Mardi Gras' might truly be combined with just about any other color.

Plant Partners

Considered individually, the colors of the variegated leaves of 'Mardi Gras' can mingle with everything. But the pattern of the variegation that they create—a wide but varying yellow border around an amoebic blotch of dark green—juxtaposes each color against the other so vibrantly that selection of neighboring plants for 'Mardi Gras' can be surprisingly tricky. The colors that go together so well qua colors look obvious and even trashy in the actuality. 

 

The most successful strategy is to partner plants with only two or three distinguishing notes, so that 'Mardi Gras' is always the busiest plant in the bed. Given how many attributes a given plant might have—overall size, size of leaves or flowers, shapes and colors ditto, texture and overall habit, seasonal peaks and troughs, and showiness of multiple parts such as bark and fruits not just leaves and flowers—you can see how focused in appeal great 'Mardi Gras' partners need to be. Certainly, the first option to eliminate is partners that are themselves variegated: Unless jumpiness is your goal, choose companions with leaves in solid colors. 

 

Here are some foolproof examples: 

-   'Sum and Substance' hosta is grown only for its habit (very broad clumps of groundcovering foliage), and leaves (huge, rounded, and somewhat puckered) that contain just one solid color (a gold that nicely matches the yellow of 'Mardi Gras').

-   So called "self heading" philodendrons clump, not climb. Like the hosta, they are grown just for their spectacular huge foliage. Philodendron bipinnatifidum combines giant leaf size with uniform coloring (mid-green) and, in a dinosaur-era kind of way, ferny texture.

-  And, of course, ferns! Fronds of forms of Dryopteris can provide the ultimate in frills and waviness, by way of groundcovering clumps whose individual fronds are almost indistinguisable amid such effervescent details. If tree ferns are hardy where you're gardening, a group of three to one side of a 'Mardi Gras' would tell the whole story, from alpha to omega, about smooth and feathery, shiny and soft, light green versus dark, light green versus butter yellow. 

 -  Grassy species of any habit and scale contrast well with 'Mardi Gras'. If you are fortunate to be gardening where the clumping forms of large bamboos are hardy, then you could have a colony of Bambusa, Chusquea, Dendrocalamus, or Otatea at the side and back of this magnolia. Or you could underplant a portion of its canopy with a small fortune in 'All Gold' hakonechloa (while dividing the rest of the underplanting area between ferns and a hosta or philodendron).  

 

All of these choices of companion plants are thrilling in themselves, partly because of their fidelity to just a few notes, not an entire aria. As long as you let 'Mardi Gras' be the fulcrum—the diva, the highlight that pulls the whole performance together—your composition can still be exuberant and even daring without risk of discord. 

 

Once you've determined the underplanting, foreground, and background combinations that surround your 'Mardi Gras' with the "narrow palette" types of plants I've introduced above, then you might finish up with a single telling detail—a brooch, as it were, for the ensemble. Tropical-climate gardeners: Is there a prize specimen orchid whose countless blooms are in a single shade of, oh, blue, burgundy, or even red? Temperate-climate gardeners: Any large-flowered clematis will also crave the same moist and rich soil that pleases 'Mardi Gras'. Flowers of 'Niobe' are red, 'Perle D'Azure' lavender, 'Romantika' deep purple.

 

Temperate-climate gardeners also have an entirely different option for highlighting their 'Mardi Gras': plants with cool-season peaks. In Zone 6, the magnolia's foliage might become too damaged by Winter to make the it worthwhile to site an 'Arnold Promise' witch hazel nearby; the shrub's vivid February or March flowers wouldn't take the curse off of the magnolia's bedraggled and half-brown leaves. But the flowers of 'Harvest Moon' witch hazel appear in November, when the magnolia foliage is still good.

 

Autumn crocuses (both the true Fall-flowering crocuses, such as 'Conqueror', and the Fall-flowering colchicum) are other options, as would be Winter aconite.

 

Gardeners in Zone 7—or those in any climate that have sited and handled 'Mardi Gras' so as to minimize foliage damage (see the second "How to handle it," below)—can choose among the full range of late-Winter and Spring ephemerals, from corylopsis and mahonia to Spring crocuses, daffodils, tulips, and alliums. Just remember to make choices so that only one plant at a time features anything other than white, yellow, or green.

Where to use it in your garden

'Mardi Gras' is still rare in gardens as well as at nurseries, so you can plant it with confidence that the tree isn't already gracing several of your neighbors' gardens. Site prominently, then, where its unique intensity of leaf variegation—let alone the occasional but so fragrant flowers—can be appreciated close at hand. Even in Zone 6, and especially when experimenting with 'Mardi Gras' in Zone 5, the tree benefits from siting and handling to lessen exposure to Winter wind. See the second "How to handle it" box, below, for particulars.  

Culture

As is typical for Magnolia, grow 'Mardi Gras' only in acid soil that is rich in organic matter. Although in its native habitat, sweetbay is exceptional among magnolias in its tolerance of moist and even seasonally-flooded ground, plants in cultivation are reported as requiring reasonable drainage year-round.

 

Part shade is tolerated, but you'll have quicker and denser growth—as well as more flowers, which are never that profuse anyway—if you provide full sun.

How to handle it: The Basics.

In Zone 6, plant in Spring only; in Zone 7 and warmer, plant 'Mardi Gras' almost any time you've finally scored a plant or two for yourself. Keeping in mind that, in Nature, Magnolia virginiana is characteristically found growing near water or in soil that is high in moisture, be generous with watering the first season. When established in the humus-rich and moisture-retentive soil it prefers, 'Mardi Gras' normally needs supplemental watering only during exceptional droughts, or if your climate's warm months are also its drier ones.

 

If you've allowed enough room for free-range maturity, the tree needs little or no formative or maintenance pruning. If you haven't, you could remove lower limbs for better clearance. Do this any time in Fall and Winter, so you'll be less likely to have encouraged regrowth.

 

If you're gardening in Zone 6, and certainly into Zone 5, 'Mardi Gras' may incur some tip dieback over the Winter. And if your Winter has been severe enough to cause dieback, it's also severe enough for late-season freezes that might do further damage. Wait until early Spring for the clean-up, so you catch everything once and for all. Because the bark on young twigs—the same ones that might experience dieback—is green, the brown-barked dead portions will be easy to spot.

How to handle: Another option—or two!

Because their branches are surprisingly flexible, and they branch readily after pruning, magnolias of any sort lend themselves to training so as to reduce overall size and provide better Winter shelter while, happily, also transforming an otherwise natural-habit plant into one whose shape is clearly intentional and, even, eccentric. As with Magnolia grandiflora, the foliage of any form of Magnolia virginiana is desirable year-round, but never more so than through the dead of Winter, when the foliage of so many other plants has fallen or is damaged by cold.

 

Because the variegation of 'Mardi Gras' is unique among magnolias, and impressively showy among broadleaved evergreens as a whole, the additional protection provided by espaliering can be all the more gratifying. See the second "How to handle it" box for Magnolia grandiflora

 

Another form of training combines this tree's quirky ability to be semi- or fully deciduous in Zone 7 and 6, with the corresponding greater reveal of its bright green bark of young twigs: pruning to a dense and compact shape. By regularly cutting back all the tree's younger stems, more and more young twigs will be encouraged, as well as a more-or-less uniform surface of growth. In the warm months, a solid layer of foliage would obscure the interior, but as Winter progresses, the leaves will be shed to reveal the green twigs beneath.

 

If just a single 'Mardi Gras' were handled this way, the result would be a dense cone or broad column of growth. If lower limbs were pruned away, the result would be a standard. If multiple plants were spaced two feet apart (or even closer if you could source them), you could create a 'Mardi Gras' hedge that would be bright green and yellow in the warm months, and still credibly green even when leafless in the cold. Depending on the severity of your microclimate in Zone 6, it might be even better to site 'Mardi Gras' with more exposure not less. Then the leaves would be shed more quickly and thoroughly. In Zone 5, it's probably wisest always to site 'Mardi Gras' with an eye to shelter: The leaves are liable to be shed even under the best of circumstances. You might, then, consider creating a 'Mardi Gras' hedge in front of a west- or south-facing wall.

 

Pruning a 'Mardi Gras' hedge in any climate stern enough to cause the full reveal of young green-barked stems suggests that the pruning be done only in late Winter or early Spring. Then new growth has the maximum time to harden before Winter. Yes, this also ensures that this mainly-Spring-flowering tree would produce far fewer blooms. But, fragrance aside, flowers of Magnolia virginiana aren't particularly showy. Besides, you could grow one of its other forms free-range, in full sun, so that its flowering and fragrance are unfettered. 

Quirks and special cases

Another common name is beaver tree. The trees are, apparently, favorites of Castor canadensis. When the rodents were still fair game, they were reported to be more readily captured if traps were baited with Magnolia virginiana wood, and in particular, its fleshy roots. This suggests that the trees shouldn't be planted for ornamental use where beavers are indigenous—but could be planted as a housewarming gift when tempting the rodents to move into the neighborhood when their considerable riparian benefits are the priority.

Downsides

Other than not being more hardy? None.

Variants

As is typical—and thrillingly so—across the entire genus, both Magnolia virginiana and its variety australis are prone to spontaneous mutations (such as 'Mardi Gras'), and can be successfully crossed with other forms of the same species as well as with some other species and hybrids within the genus.

 

Considering that there are over two hundred Magnolia species to begin with—plus that their flowers' tempting range of colors and sizes is astonishing already—the certainty that new forms will reach the marketplace annually is 100%.

 

Looking first just among the named cultivars of australis: 'Sweet Thing' is dense and, to just eight feet, comparatively shrubby. 'Green Shadow' is fast-growing to thirty feet in Zone 7 and warmer. The foliage of 'Henry Hicks' is more persistent over the Winter. 'Moonglow' is distinctly upright. Foliage of 'Willowleaf' is, indeed, notably narrow, whereas that of 'Santa Rosa' is notably larger.

 

Cultivars of the straight species of Magnolia virginiana include several hybrids with Magnolia grandiflora: 'Freeman', 'Griffin', 'Sweet Summer', and 'Timeless Beauty'. The goal of such crosses is, presumably, to improve hardiness while maintaining the larger foliage and flowers of M. grandiflora. Given that some cultivars purely of M. grandiflora can be grown into Zone 6, however, there's little benefit to be gained: The flowers and foliage of the pure grandiflora cultivars are superior to the hybrids with Magnolia virginiana.

 

Despite the many hundreds of mutations and hybrids across the entire Magnolia genus, it is striking how few named forms there are whose calling card, as with 'Mardi Gras', is colorful foliage. For example, to my knowledge there are no magnolias with burgundy or gold foliage. The contrast with say, Fagus or Acer is extraordinary: Beeches and Japanese maples are veritable funhouses of colorful foliage. True, their apetalous flowers are miniscule, whereas the petals of magnolia blossoms are among the largest of any plant hardier than Zone 10.

 

I'm aware of only three variegated forms of Magnolia other than 'Mardi Gras', and none is remotely as showy. Leaves of Magnolia denudata 'McCracken's Variegated' and 'Elizabeth Variegated' are stippled and striped in yellow. To my eye, their look could just as well be that of some ailment or deficiency. Leaves of 'Fancy Dude', however, are variegated like those of 'Mardi Gras', with a wide irregular yellow perimeter surrounding a green center. Alas, the coloring is only strong in the Spring. The variegation of 'Mardi Gras', then, is unique among magnolias in being at once prominent, enduring, and clearly ornamental.

Availability

On-line and, very rarely, at specialist retailers.

Propagation

By cuttings. Those from younger trees are reported to root much more easily. Perhaps 'Mardi Gras' should be kept in propagation steadily, then, with each generation of young trees providing the fast growing and easiest-to-root cuttings that will grow into the next generation of young trees.  

Native habitat

Magnolia virginiana is native to coastal North America from Massachusetts south to Florida and west to eastern Texas. The variety australis is native to the southern portion of the straight species' range, and is reported to be more evergreen and taller, as well as slightly less hardy. The variegated cultivar 'Mattie Mae Smith' was discovered in 1995 by a nurseryman in Chunchula, Alabama, John Allen Smith, who named it after his mother. It isn't unusual for a plant's patent name ('Mattie Mae Smith') to be different than its marketing name ('Mardi Gras'.)

 
 
FacebookTwitterRSS Feed

Stay in touch!

 

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

 

* indicates required