A Gardening Journal

The Best Season Ever: Fire Vine

Ipomoea lobata flowers closer 071015 640 

 

Easy from seed, quick to establish, and heavy with flowers even at the height of Summer's heat, fire vine is one of my new favorites. As long as it can keep climbing higher, it can keep growing—and forming more flowers. And what flowers! Spikes of inch-long blooms in a sequence of fiery color, from near white at the bottom to smoldering red at the top. 

 

Ipomoea lobata flowers fingers 071015 640

 

The flower spikes are formed in pairs.  Happily, each stem is a dark burgundy, which takes the fiery color spectrum further into its dark zone. Just one flower in a spike seems to achieve fertility—as shown by the white projecting "tongue" of stamens and pistil—at a time. In the spike above, the lowest flowers of each spike have already matured and their petals have fallen, while the next-higher flowers are, literally, in full flower. Higher-up flowers mature only slowly, lightening to palest yellow white as they become fertile. A given spike's blossoms can be in place over many weeks, so that the overall number of spikes and flowers keeps increasing through much of the Summer.

 

In the picture of early July below, three plants of Ipomoea lobata are thriving in a large terra cotta pot. Their stems were already rocketing up a tripod formed of ten-foot lengths of rebar. 

 

Ipomoea lobata main tripod 071015 640 

 

Spikes of blossoms are emerging from bottom to top. By early July, these stems had already exceeded the top of the tripod. They were already over eight feet tall.  

 

Ipomoea lobata upper tripod 071015 640

 

Now, if I can just provide support that will be as high as fire vine could ever need. Poles ten feet high turned out to be just the beginning. If there were an additional four, six, eight, or even ten feet of pole still higher, would the stems have just kept climbing? The only way to find out is to have that ultra-high center pole in place when I replant this pot next Summer.

 

Below, flowers of the only named cultivar, Ipomoea lobata 'Citronella'.  

 

Ipomoea lobata Citronella 091415 best 640

 

In line with the lemony inference of 'citronella', their higher-and-higher flowers never show the deep red of those of the straight species. The mid-level buds flirt with deeper yellow and orange, but the very highest buds show just pale yellow, not darker and darker red. 

 

 

Here's how to grow this ultra-enthusiastic annual vine:

 

Latin Name

Ipomoea lobata

Common Name

Fire vine, also commonly called Spanish flag, from the flowers' alignment along just one side of the stem (and, so, like a flag), and their orange and red coloring, imitating that of the flag of Spain in particular. 

Family

Convolvulaceae, the morning glory family. 

What kind of plant is it?

Subtropical vine that is normally grown as an annual.

Hardiness

Zones 10 - 11.

Habit

Twining and upward bound. Stems emerge from side branches naturally, so pinching isn't necessary.

Rate of Growth

Fast.

Size in five months

Young plants set out in mid-Spring can twine four to five feet by early Summer, and several times that high by mid-Summer. This year, I planted three in a huge, high terra cotta pot into which I had plunged three ten-foot lengths of rebar to make a tripod. My vines were at the top—eight feet tall, in other words—by the date of these pictures, July 9. Next year, I'll sink a fourteen-foot rebar at the center, to provide fourteen feet above ground for the vines to race up, not just eight. If they over-top that, then I'll switch out my three ten-footers for three sixteeners the following year—with a twenty-footer up the center.

Texture

Lacy and airy. Although the leaves are not small, and the vine's foliage mass can be solid, the profuse, upward/outward-projecting one-sided racemes of flowers create an outer layer that is see-through as well as eye-catching.

Grown for

its flowers: Each is small and somewhat tooth-shaped. Eight or nine of them are arrayed with precision up just the outer edge of each of many short racemes. The racemes are in pairs, angling out from one another only as far apart as the arms of a tuning fork; the arms project upward and outward from the general mass of the vine's growth. Grow Ipomoea lobata on structures that call attention to all of this unusual but tidy geometry. See "How to handle it," below. 

 

The color of each flower correlates to its position up the raceme. The lowest flower is the oldest, and is always the lightest: nearly white. The next two or three above it are a bit more yellow, but higher ones are darker and darker shades of orange. The very top two buds are fiery red. These top flowers are always noticeably smaller than the paler ones below. Over a month or two, these orange and red flowers lighten up, bottom first, and display the long tongue-like center stalk that contains both stamens and pistil; the very top, and darkest, blooms never do seem to mature. But they do retain their lively dark ember-glow color. 

 

I have never had the pleasure of observing a hummingbird visit that was long enough to show whether the birds can feed from these small orange and red flowers, which seem closed even upon determined inspection—or whether they visit only the lower, large and fully fertile yellow-to-white flowers. In any event, just one flower on the raceme displays the central stalk at a time and, here, too, the progression is orderly, with the bottom flower first, then the next and the next.

 

Individual buds are remarkably long-lasting, so the show of a given raceme can last, seemingly, for months. Flowering is slow to start, but then becomes stronger and stronger through the dog days. New racemes come on line with ever-increasing frequency as Summer peaks. The vines seem to enjoy all the hot weather my New England Summer can provide, and by August, the display is showstopping.

Flowering season

Young plants need three months and more to begin flowering; even if you start seeds indoors a month before the last frost, you still might not see flowers until late June. In climates with hot summers (almost anywhere in the eastern United States, for example) flowering increases dramatically through July into August. In my experience, by September the peak has been reached, and the show is on a slow slide until frost. In cool-Summer climates (such as in, say, Great Britain, or neighborhoods in San Francisco with frequent afternoon fog), flowering can be slower to ramp up but also longer to increase to peak profusion. (One British source reported that flowering was prolific into October.)  My vines that were going at full tilt in August will have only scattered individual blossoms by October—and those will be the last, upper, flowers of racemes formed back in August, not the full-budded display of young new racemes.

 

Does flowering diminish because the vines' overall growth has slowed as the full extent of the available structure has been reached?  Because the day length is shortening?  Because the vines have grown as much as they can for a given volume of available soil?  Because the hottest of the Summer's weather has passed, and evenings are becoming just a bit chilly?

 

One possibility is that any given vine has but one "arc of vigor" in it.  If your choices hasten the run-up to full flowering, they also shorten that peak's duration, but if a vine grows more slowly and comes into flower later, it might still be working up to its peak when cut down by frost.  The show is less spectacular all along, but you are spared its increasing threadbareness when the peak is past.  My pot of the straight species was quick out of the gate and astounding all August, but as of this writing is noticeably thinned and on the way out.  But my pot of the sole (to date) cultivar, 'Citronella', was slow all Summer and is only now coming into flower; it promises to continue gathering in strength and beauty right until frost.

 

See the second "How to handle it" for some easy experiments that might reveal answers.

Color combinations

True to its common name, the flowers of Ipomoea lobata embrace nearly all the colors of flames: white, deep yellow, orange, and red.  With such variety in each raceme, the last thing needed near fire vine would be a color not clearly on this hot-color spectrum.  Of those colors not already present in the flowers themselves, burnt umber, burgundy, and ebony are also plausible: They continue the "hot" line past red, and they are already present in the raceme's stem.

 

Although, yes, blue is often present in a flame and, so, is conceptually at home with the "fire" vine name, it will be perceived coloristically as a contrast—the last thing needed when so many other colors in the fire vine flower spikes are already in play.  It's safest, then, to limit yourself to colors and shades already present in the vine's flowers.

 

The color spectrum of the flowers of the 'Citronella' cultivar (see "Variants," below) is even narrower, as if the deep orange and red of the "hot" line has been cut off.  So, you could choose to add them back in, in addition to the burnt umber, burgundy, and ebony that could be brought into view near flowers of the straight species.

Plant partners 

Ipomoea batatas provides opportunities as well as pitfalls for partner plants.  Its unusual multi-colored racemes of flowers are so interesting in themselves that nearby colors should be restricted to those immediately on the same hot-color spectrum—and, preferably, not via a similar multi-color splash. Instead, choose partners that present just one of the fire vine's highlighted colors and, at all costs, avoid those that are hawking blue and pink after July fourth.  

 

Its quick twining growth means that it will just as obediently clothe a tuteur or an ad hoc tripod, or nearby branches of a large-enough host plant, as it will smother a too-small host and overwhelm a too-short tuteur.  Its somewhat long "gestation" period before flowering means that you're looking at just green foliage until Summer is well underway—but, on the other hand, this also means that, as long as they are through in June, it doesn't matter what color the flowers of partner plants are.  (Do go wild with blue and pink, then, as long as those plants are done flowering by July.)  And its flexibility in being grown in large containers, not just in the ground, means that the vine can tango with otherwise perfect host plants (hedges, say, or huge ground-sweeping trees) that wouldn't permit so much as crab grass to grow under their feet.  Lastly, large mounding partner plants can provide the shade at the roots that fire vine is said to appreciate, especially when grown in containers.

 

The following partners go toe-to-toe with fire vine in terms of Summer-long performance and exceptional visuals—while still being happy team players coloristically:

 

To bring the colors at the darkest end of the hot spectrum into play, go for plants with deep burgundy foliage, like purple-leaved smokebush, Cotinus coggygria 'Velvet Cloak'.  Coppice this shrub each Spring that you pair it with Ipomoea lobata, so that the shrub produces only more of its harmonizing foliage, and none of its totally-clashing heads of dusty-pink "smoke."  The dark foliage of Euphorbia cotinifolia seems, at first, like a good substitute, except that its leaves mature to a purple clearly infused with the verboten blue.  Smokebush leaves mature to always-compatible shades of ebony and burgundy. 

 

And what about setting your largest-possible container of fire vine at the edge of the lowest branches of a dark-purple beech, such as Fagus sylvatica 'Riversii' or 'Spaethii'?  The vine's eager stems could explore the lower fifteen feet of a portion of the beech's vast canopy—like an immense corsage worn at the hem of a ball gown—while the exciting multi-color flowers tempt you to enjoy the beech closer at hand, not just in the distance.

 

Any number of high- and late-Summer daisies feature flowers in shades of yellow, from school-bus to the palest butter cream.  Can you site your largest container of tripoded fire vine at the front of your largest colony of Helianthus maximiliani 'Lemon Yellow' or Helianthus giganteus?  Or in back of a sweep of Silphium terebinthenaceum (whose gigantic banana-leaved foliage would also shade the fire vine's container)? 

 

Or, what about setting a large containered fire vine near a yellow-needled conifer, such as Metasequoia glyptostroboides 'Gold Rush'?  The vine's green and, comparatively, large leaves would be an exciting overlay to the foliage of the tree's lower limbs—and, when flowering begins in July, the conifer and vine are both, suddenly, a must-see flourish.

 

Plants that mound only to three or four feet—and that remain in good shape right through to frost, instead of thinning, fading, or splitting open—can be just the thing at the hot and sunny front of any containered fire vine.  Consider Ilex crenata 'Helleri' or 'Beehive', Pinus mugo—or rhodies and azaleas: Even if those bear flowers that are pink and mauve, their flowering season is through by the end of June.  Rhododendron x laetevirens would be perfect, in that it hardly flowers at all.  Hydrangeas usually won't work, because all of their flowers eventually think about what a swell color pink is.  If, though, you grow a Hydrangea quercifolia just for the foliage—which, given its size and unique-in-hardy-plants shape , as well as the shrub's overall suitability for a fire vine fronter because of its bulky full-to-the-ground habit and ability to look fresh the whole season, is almost a better idea than including the flowers—then you'll have one of the better pairings.  The oakleaf foliage is so large it makes the fire vine leaves look delicate, and it doesn't have a drop of blue in it, while the shrub's fuzzy orange stems might just become tall enough to call out to that shade in the fire vine's flowers.

 

Oddly, few herbaceous plants qualify as foreground mounders for fire vine.  Of those that are still going full steam ahead August into September, which do not veer into the forbidden zones of blue and pink?  I can't think of single ornamental grass.  Even those whose foliage avoids blue in favor of solid green or variegation with yellow still tend to have panicles in incompatible shades of silver, tan, or pinkish-burgundy.  If pinched, small-flowered chrysanthemums might stay bushy enough and, goodness knows, their flowers can be had in any of the shades favored by fire vine.  The flowers of most asters, though, are in the unworkable shades of blue, violet, and pink.  The burgundy foliage if Ligularia 'Brit Marie Crawford' would be as appropriate as its spikes of deep-yellow daisies—but this perennial needs afternoon shade instead of providing it.

 

Perhaps best—and from two quite contrasting perspectives—would be bush dahlias and large ferns.  The dahlias—think 'Summertime' and 'Bishop of Llandaff'—don't need staking, plus their foliage is high enough to shade the fire vine pot and, of course, their flowers will harmonize sumptuously and right until frost.  If your ground is sufficiently deep and moisture-retentive, you may be able to grow any of the taller hardy ferns in the full sun that Ipomoea lobata prefers.  Osmunda regalis and Matteuccia struthiopteris would both provide a context that is elegantly textural but coloristically neutral.  This is no problem for fire vine, of course, whose display is big, colorful and, literally, color-full.

 

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The white-to-apricot-and-orange coloring of Ipomoea lobata 'Citronella' rules out all the tall daisies as well as anything with yellow foliage.  Burgundy foliage and flowers, green hedging, and tall ferns, though, are still terrific.  

Where to use it in your garden

Ipomoea lobata creates such a bright and big show that vines are effective even in the distance.  But the racemes of fire vine flowers are very eccentric in their one-sided array up the flower stems and sequenced coloring.  Plus, each individual flower's progression from bud to maturity to round seed pod is (now that you've begun to notice) strangely slow for a vine that, overall, has been growing at warp speed.  It would be rude not to site plants where these details can be enjoyed at the closest range.

 

Site, then, where you can easily access the plant during its entire growing season.  I prefer growing it in a huge pot that I can place prominently on the terrace.  With a supporting structure (a tripod of three lengths of rebar whose lower ends were plunged right to the bottom of the pot) that was ten feet tall overall, the container was startling and impressive from the get-go.  By the time the young vines had raced to the top—barely six weeks from planting—what had seemed a dizzyingly tall structure was, actually, just barely high enough.

 

A containered fire vine, then, is likely to be a dramatic and even monumental presence by virtue of just its size.  If you have the room and the inclination, plant up a pair of such containers, or even a quartet, which would be strong punctuation even to large spaces in the far distance.  I might, for example, place one such pot at each corner of the reflecting pool, which begins about two hundred feet out from our house. They would beckon effectively even from such a distance.

 

Another possibility would be to let Ipomoea lobata climb up the south face of a very high and densely-pruned evergreen, like a hedge of yew or a column of arborvitae.  Or a large enough free-range shrub or conifer whose foliage canopy extends nearly to the ground.  The host plant would need to be so tall that the vines can't overtop it, otherwise it would look overrun.  It's unlikely that the soil near any such large evergreen would be loose and moist enough to host fire vine directly; instead, plant in a large container that abuts the lowest foliage of the host.  Keep in mind that the vines will be that container's-worth tall from the start and, likely, will stay a bit taller than otherwise the entire season.  The hedge or column will need to be all the higher, then.

Culture

Rich, well-draining soil encourages the quickest penetration by roots and, hence, the most vigorous upper growth.  Vines are much more floriferous in full sun, but will flower a bit even in part shade.  The roots reportedly appreciate a bit of shade—i.e., the comparative coolness that shade would ensure. When growing Ipomoea lobata in a container (which I recommend), then, try to have the container itself cast into shade by partner plants, even as the vine's above-ground growth enjoys plenty of sun.  See "Partner plants," above. 

How to handle it: The Basics

Unless your growing season is long and hot, you're probably going to have started Ipomoea lobata from seed indoors some weeks before your last frost. See "Propagation," below. Or you're going to have purchased young plants at a plant sale or nursery. Either way, you'll have a young plant to set out for the season when the weather is solidly warm. The small vines will have already demonstrated their predilection for growth that is quick as well as twining, so have your supporting structure ready.

 

Ensure enough water for establishment, then water only when needed.  Vines growing even in a very large container could need watering almost every day during the height of the Summer.  Vines growing in the ground in deep and moisture-retentive soil probably will not need watering at all after they have become established.

 

Although fertilizers with a particularly high amount of nitrogen are reported to produce more foliage at the expense of flowers, my experience has been that a general-spectrum fertilizer helps encourage more of each, especially as my plants are grown in a large container where the necessarily frequent waterings inevitably leach out water-soluble nutrients.  I splash some fish emulsion into my watering can at least once a week. 

 

A very tall tripod is an easy, effective, and stylish supporting structure: Tips of stems that are still just inches long will feel the presence of something to twine on, and will begin to race up them as a result.  Depending on the width and height of your tripod—and ten feet should be a minimum anywhere Summer temperatures will regularly enter the eighties and nineties Fahrenheit—the angle of the inward-sloping poles of the tripod will seem, more or less, to be mirroring the outward-upward angle of the vine's racemes of flowers.  For quick and more uniform coverage, I plant one vine at the base of each pole.  Poles can be almost anything.  I use lengths of rebar, around which the vines climb quickly and, thanks to the rusty and ridged surface, hold tight in their upward race.  You could probably use long bamboo poles or, even, just lengths of rough twine tied to the top of a central pole and staked to the ground.

 

Formative training and deadheading aren't necessary, but I do find that, later in the season, occasional leaves can turn brown and become trapped in the tripod's interior tangle of stems.  Before each of our outdoor parties, I try to fish them out.

 

I'm not aware of any other named cultivars than 'Citronella', so seeds of the straight species are almost certain to come true.  There are a pair of them in each of the round, pea-sized pods.  This year I'm growing 'Citronella' as well as the straight species, but at some distance away from one another.  I'll collect 'Citronella' seeds, too, to see if they also come true.

 

After frost has killed the vines, it's easy to remove the dead growth by disassembling the tripod or cutting down the lengths of twine.

How to handle it: Another option—or two!

If you're training Ipomoea lobata up a tripod, keep nearby plants safe from outward-wandering tendrils:  Part of the appeal of the vine's show is that it will form a narrow pyramid of growth, from which stray stems would only be a distraction.

   

If you're growing the vine up the front of a hedge (or free-range shrub or tree whose canopy begins low to the ground), the nearby soil is likely to be congested with roots already.  You'll need to grow the fire vine in a large container.  Pair the vine with a hedge that is fairly slow-growing and can be trimmed in late Spring or, even, early Summer.  Then, the hedge will maintain that much more of a clean line through the season, which will enhance the contrast with the fire vine's free-ranging growth atop it.  Taxus or arborvitae are probably the best choices: They can be pruned at almost any time, and can be trained into dense surfaces of near architectural precision.  So that the vine will receive plenty of sun, the hedge will need to face south or west.  Depending on when you schedule the hedge's trim, you may want to have been growing the fire vine in a training pot during Spring and even into early Summer.  A two-gallon plastic nursery pot would be big enough, with just a single pea stake in it for the fast-growing stems.

 

After the trim is done, then you can lug your largest terra cotta pot to a sunny spot right alongside the hedge, fill it with extra-nutritious potting soil, and carefully unpot the vine from its two-gallon pot and plant it in the display terra cotta.  To get the vine growing onto the sunny face of the hedge, you could carefully lean the pea stake back into the hedge's outer branches, and let the stems explore the hedge at will.  Or you could (carefully!) cut the pea stake off at ground level, and lay it (with the fire vine twined along it) nearly horizontally along the face of hedge.  This will encourage even more of the side stems of the fire vine to form; they will climb up the face while covering a broader swath of it from the beginning.

 

If your terra cotta is really big—twenty inches or more across at the top—you could have two such pea-staked vines ready.  Sever both stakes at ground level, aligning one horizontally to the left, the other to the right. 

 

If you're growing the vine up a tall columnar or upright tree, be sure it's at least fifteen to twenty feet high so that the host will never appear swamped or enveloped by the vine.  As with a "hedged" fire vine, place as large a terra cotta pot as you have adjacent to the tree's lower foliage.  A columnar tree this tall is unlikely to receive pruning, so you can plant two or three young starter vines directly into the terra cotta, and let them explore upward however they will.

 

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Wherever you might grow fire vine in a container, consider siting such that the container itself receives afternoon shade even as the vines growing from it are in full sun.  Given the quick height the vines will quickly attain, perennials and even medium-sized shrubs might already be in place.  Or you could have a companion "nurse" container planted and in place just for this purpose.

 

See "Partner plants," above, for suggestions.

 

__________

 

To understand how the seasonal cycle of flowering might be affected by choices in culture and handling, try experiments such as these:

 

To ensure that vines never flag, even over a longer growing season, don't sow seed before frost.  Instead, germinate "in real time," by sowing outside only after Spring weather has warmed up.  Your vines will probably be at their best from September until frost.

 

To ensure an earlier peak (but perhaps, then, an end-of-Summer fade), germinate indoors by sowing in late Winter or early Spring.  Plant outside only after the weather is reliably warm day and night, and fertilize liberally; plant in-ground (or place your container) where the vines receive all possible sun.

 

To test whether vines stop forming new racemes of flowers, at least in part, because they have run out of still-higher structure to climb and, hence, have slowed growth in general, establish several different plants, providing structures of differing heights for them to ascend.  A structure six to eight feet high will normally be the bare minimum; offer heights of twelve, fourteen, sixteen, and eighteen feet, and see which vines are the most floriferous at any given time—and which maintain their peak show longer.

 

To test how flowering is affected by root congestion and scarcity of nutrients, establish several vines, but fertilize only one or two of them.  Grow a series of vines in different-sized pots, watering and fertilizing them all similarly, to see how the quantity of available soil volume affects performance.

Quirks and special cases

See "Flowering Season" and the second "How to handle it" boxes, above, for experiments that might reveal how to handle Ipomoea lobata to best time its peak flowering.

Variants

Flowers of the racemes of 'Citronella' lack the darkest flower shades that occur at the upper tips of racemes of the straight species.  Their palette is yellow at the bottom to just apricot at the top; as with the species, the flowers mature sequentially up the raceme, becoming lighter and lighter in the process.  Freed of both dark orange and red—the "fire" of the common name, true—this paler Ipomoea lobata cultivar can be grown in less hotly colorful contexts—even those that dabble in pink or blue.  See "Plant partners," above, for suggestions.  

Availability

Seed is readily available online; young plants are often available at nurseries and plant sales.

Propagation

By seed.  In frost-free climates, the seeds are hardy, making Ipomoea lobata a hardy annual—and, probably, quite a pest.  Seeds are reported to be slow to germinate—three weeks and longer—even when, as is usual with forms of Ipomoea, they are soaked overnight in warm water before sowing.  If you can first hold individual seeds securely (try needle-nose pliers) and you have a small but sharp knife, knick the outer layer of the seed before the soak.  Nail clippers would be another tool to try.  However you achieve it, the nicking will help water penetrate more quickly and thoroughly.

 

Plant seeds individually in small starter pots, and when transplanting into a larger pot, try not to disturb the soil mass.

 

Fire vine takes twelve to fourteen weeks from sowing to begin flowering, so starting seeds indoors six or eight weeks before the last frost (or purchasing plants at any time in Spring) is really worth it if your goal is a show that is clearly ramping up in July, and is at full tilt by August.

Native habitat

Ipomoea lobata is native to Mexico.

 
 
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