A Gardening Journal

Carolina Jasmine

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With these bright yellow trumpets, Carolina jasmine is fool-proof color, at least from the Carolinas south.  In New England it's a bit of an experiment—and if successful, a triumph.

 

The buds emerge from the leaf axils of last season's growth.  A happy vine can have thousands of flowers.

 

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Read on for strategies to succeed with Carolina jasmine far north of the Carolinas.

 

 

Here's how to grow this vibrant Spring-blooming vine:


Latin name

Gelsemium sempervirens 'Margarita'

Common name

Carolina Jasmine, Yellow Jessamine, Gelsemium

Family

Gelsemiaceae, the Jessamine family. 

What kind of plant is it?

Evergreen twining vine.

Hardiness

Zones 6 - 10.

Habit

Twining when it can.  Also happy as a groundcover and a container or wall-top cascade.

Rate of growth

Fast in milder climates. 

Size in ten years

Size varies with opportunities for twining and layering, as well as the severity of the climate.  Can twine ten to twenty feet, but is easy to control.  Where the vine doesn't experience winterkill, and has plenty of room to romp, coverage can be indefinite.  Much smaller in colder climates.

Texture

Full but loose; with pruning can become dense enough to look solid or even heavy.

Grown for

its flowers.  Typical for Gelsemium species and cultivars, those of G. sempervirens are bright yellow trumpets, an inch across at the front, that attract butterflies and hummingbirds.  Those of 'Margarita' are a bit larger than the species.  They have a light fragrance.


its foliage.  Caroline jasmine is evergreen and can twine quickly to form a screen or groundcover that provides full coverage.

 

its hardiness.  'Margarita' is reported to tolerate Winters in Zone 6; G. sempervirens usually doesn't survive colder than Zone 7.  See "How to handle it," below, for how to maximize hardiness.

 

its resistance to browsing:  All parts of the plant, including the nectar, are poisonous to the usual four-footed browsers, such as deer and rabbits—as well as to people.  Avian and insect pollinators, however, are not at risk. 

Flowering season

Spring; early Spring or even late Winter in Zone 7 and warmer.

Color combinations

There's no avoiding it:  Gelsemium flowers are the same brash yellow as those of the omnipresent forsythia.  But because the flowering is a bit later in Spring, there's usually more green growth and additional flowers to help such a bright color integrate into the garden.  Easy companion colors include white, blue, dark green, and the lighter shades of yellow. 

Partner plants


If you're growing gelsemium where its hardiness is an achievement, not a guarantee, you'll need to choose partner plants that can assist, or at least not get in the way of, your tactics to enhance hardiness.  See details in "How to handle it: Another option—or two"? below. 

 

Growing gelsemium as a groundcover?  Tall Spring bulbs could grow up through it.  The flowers of many daffs and narcissi associate well with the bright yellow of the gelsemium. 

 

Growing gelsemium up lattice that is backed by a fence or wall?  If the wall is masonry, you could establish ivy on it.  This would provide yet another layer of wind-muffling:  Wind that slides in back of the gelsemium wouldn't just be shunted down the wall to, so to speak, bite the gelsemium in its hind end.  It's easy to establish hostas at the base of the lattice, and there are plenty of gold-leaved cultivars that can call out to the gelsemium flowers.  

 

Growing gelsemium up through an evergreen shrub or tree?  Conifers will provide the best contrast with the smooth-edged and pointed gelsemium leaves, and are easy to partner with bright yellow, too.  Yews provide the ultimate in dark-green contrast; for a milder contrast of yellow-green, choose Chamaecyparis or, as I have, a soft-yellow Himalayan cedar.  The yellow foliage of some Chamaecyparis cultivars is so bright, that the mid-green leaves of gelsemium are, themselves, highlighted, not just the vine's vivid flowers. 

Where to use it in your garden

Gelsemium is nothing if not flexible, succeeding as a twining climber, a diligent groundcover, and a cascader when planted in containers or atop retaining walls. 

Culture

In climates where it is solidly hardy, plant in sun or part shade, in average soil.  In Zone 6 and the colder parts of Zone 7, full sun is better, as well as a location with good drainage, especially in Winter.

How to handle it:  The Basics

In mild climates, plant in Spring or Fall, providing enough water to establish.  At the cold end of its hardiness range—the north edge of Zone 7 and, definitely, anywhere in Zone 6—plant only in Spring.  See below for tactics to enhance hardiness.

How to handle it: Another option—or two?


Gelsemium is grown for its early-season flowers.  If you wanted only a vine that was evergreen, you could plant ivy or euonymus, instead, either of which is much hardier.  Slightly less hardy, but still evergreen, is Stauntonia, where the foliage is as engaging as the flowers.

 

Gelsemium is only worth growing, then, where an enthusiastic floral display is possible.  The buds emerge from last year's growth before any foliage with Winter damage can be shed or can be hidden by new growth.  Plus, the leaves are relatively small as well as profuse, and leaves that are only somewhat Winter-damaged are usually retained, and so detract mightily from the show of the early flowers.  It would be an awful tedium to have to snip hundreds of damaged leaves away from the rest of the growth.

 

On all counts, then, gelsemium is trickier to overwinter than borderline plants that are readily deciduous, or can be cut back to live portions that will resprout and produce flowers later in the season.  Its seasonal peak is right in Spring, so there isn't time for the plant to recover first.  Other Spring-blooming plants with similar hurdles include Clematis armandii and Rosa banksiae.  Of course, I have to try them, too. 

 

So, let your overwinter strategies be informed more by the need to preserve gelsemium's foliage in good condition than just the need to shelter the plant itself.  Because the vine doesn't have the gift of easy deciduousity, you can't just wrap the beast in burlap, or move a potted specimen to the dark comfort of your basement.  Instead, train the vine up south- or west-facing lattice that's backed by a high and wide wall; a free-standing lattice would only encourage upward growth that would therefore be cruelly exposed to Winter wind.  You could even cover the exposed face of the latticed growth with a sheet of wind-baffle fabric, or spray with antidessicant, or both. 

 

Shorter plants are is usually a bit protected by nearby taller ones.  If you train gelsemium as a rectangular patch of groundcover, you can lay an old screen door on top of it to buffer Winter wind.  In January, lay the evergreen boughs of end-of-year celebrations atop the screen for additional wind muffling.

 

Yet another possibility is to establish the vine at the base of an evergreen bush or tree into which it can climb.  (I'm training my gelsemium up one of the poles that supports the espalier frame for my yellow-needled Himalayan cedar.)  The host plant acts as both a scaffold and a wind-screen—and, if the vine is planted under its canopy, as a kind of living mulch.  Upward growth is most likely to remain viable when it twines up through the center of the host plant; gelsemium is shade-tolerant, so can grow in the interior of the host as well as at the exterior.  With luck, that interior growth will be able to extend to the host's perimeter, and the flowers will gently sparkle throughout.

 

If you have the room to overwinter a potted gelsemium indoors, give it bright light.  Water as needed; the plant may well remain active.  Flowering could begin in March or even February—but may also be long over by the time you move the pot outdoors after frost danger is over in Spring.  A potted gelsemium, then, might be more effective as a cool-weather conservatory display than as showpiece outdoors in your garden.

Quirks or special cases


Because gelsemium accepts pinching and pruning readily, you could easily grow it as the filler of a topiary form.  Prune as heavily as needed right after flowering is through, but resist the urge to pinch and tidy in Fall or Winter:  You'll be removing the very growth that will produce the Spring flowers.  A gelsemium topiary is more interesting in shape than one whose growth is controlled for size only.

Downsides

Because the vine is evergreen, it needs special handling if the foliage is to stay in good enough condition by the time the early-Spring flowers emerge. 

Variants

'Plena' has double flowers.

Availability

'Margarita' is available on line and sometimes at retailers.  G. sempervirens itself is widely available at retailers in its hardiness range. 

Propagation

By cuttings and by layering.

Native habitat

Gelsemium sempervirens is native to the Western Hemisphere, from the southeast United States to Guatemala.

 
 
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