A Gardening Journal

The Best Season Ever: 'Fireglow' Spurge in Bloom

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Voluptuous as well as eccentric, the floral display of 'Fireglow' spurge is one of mid-Spring's highlights. You may well have plenty of tulips and lilacs and rhododendrons. Could anyone have too many euphorbias? 'Fireglow' is, perhaps, the first to try—or the next to add to your collection.

 

To my eye, the hallmark of a great flower is that it is even more interesting at close range. By this yardstick, the display of Euphorbia griffithii 'Fireglow' is wild. Indeed, it is so quirky that special terms are needed. Those pink-petaled flowers? The "petals" are modified leaves, known as bracts. But these are special bracts known as cyathophylls. They surround the cyathia, the term for the cluster of small flowers within. 'Fireglow' already has "normal" bracts: the large orange leaves on which the cyathia seem to be lounging. 

 

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As the entire cluster matures, the display changes and, at least comparatively, becomes simpler. The pink-backed cyathophylls hare opened, showing off their orange inner faces. The orange bracts immediately below them have changed to orange.

 

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The actual flowers are the tiny bits at the center. The female flower is in the dangling thing with the ball mid-way down, and three slender arms beneath. The minute yellow-pollen-tipped males are just barely visible at her base. The four rounded yellow petal-like things are nectar glands.

 

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Looking even closer, the gorgeous pink veining of the cyathophylls is clear. Even this close, the minute male and female flowers still seem insignificant compared to the surrounding pillowy nectar glands.

 

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I clipped off a single cyathium in hopes of presenting its parts more clearly. The dangling female flower—which can mature to a showy green fruit—is obvious, as are the surrounding nectar glands. The guys?  Still just specks of whatever—in this case, brown—at the base of the female.  My hunch is that the nectar glands' role in attracting pollinators is as important as their size is big.

 

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As is usual for spurges, the least little snip releases a surprising amount of sticky white sap. In the picture below, look at the flow from the cut raspberry-colored stalk that had held the cyathium above. The sap is poisonous as well as sticky, and is one reason that Euphorbia is normally avoided by browsing creatures.

 

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As if all of these oddities weren't sufficient, at the very center of the entire display of cyathia and their accompanying rings of leafy bracts, there's a lone stalk tipped, in part, with still more of those pillowy yellow nectar glands. I think of these as the initial tempation for pollinators: When the cluster is young, the cyathia are recumbent on the large orange bracts. Until their cyathophylls open wider, the big attractions—all those nectar glands, cyathium after cyathium—are still under wraps. 

 

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The nectar glands on this central stalk, then, are the teaser, the forecast of the bounty to come.

 

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Who knows what the tufty white bits are? This being a Euphorbia, they could be yet another unique-to-the-genus structure, with yet another quirky function.

 

Here's how to grow this easy perennial:

Latin Name

Euphorbia griffithii 'Fireglow'

Common Name

Fireglow spurge

Family

Euphorbiaceae, the Poinsettia family.

What kind of plant is it?

Rhizomatous herbaceous perennial.

Hardiness

Zones 4 - 9. 

Habit

In Spring, narrow spear-like stems emerge from the ground with the single-minded upward thrust of asparagus—pink asparagus, at that. Long narrow leaves, reminiscent of those of willows, loosely clothe the stems. Short side stems emerge from the crotch of some of the upper leaves. As flowering becomes imminent (as a result of some combination of sustained warmth, change in day length, the length of time the new stems have already been able to grow, and the stem height already obtained), subsequent leaves are somewhat shorter and are spaced more closely. They then become flushed with orange as the terminal clusters of complex flowers emerge.    

Rate of Growth

Medium to fast.

Size in ten years

Two to three feet tall and wide. Reported as spreading more readily in richer, moister soils.

Texture

Denser with more sun, where its willowy-leaved stems can be numerous and close enough together to echo the texture and density of a Daphne. Looser in part shade. See "Culture," below, for guidance on the conditions that make provision of full sun possible.

Grown for

its flowers and colorful bracts: Euphorbia flowers are tiny, with such eccentric complexity and array that their assemblage has been granted its own name, a cyathium. Although there is variety across the many hundreds of Euphorbia species and cultivars, E. griffithii follows the typical configuration: a larger and (comparatively) more prominent female flower (easily recognized because of its three-armed style and a bulging I-swallowed-a-medicine-ball ovary halfway down) with a scattering of smaller male flowers at its base. Immediately outside of them are four yellow pillow-shaped things, immense by comparison. These are nectar glands.

 

Cyathia are borne at the tips of Euphorbia stems, often in groups. Those of 'Fireglow' emerge in a loose ring. The most prominent detail of Euphorbia "flowers" is actually the bracts that closely cup the cyathia. These can be almost any color from white to pink to yellow to orange to brick red. Those of 'Fireglow' are a warm mix of pink lightening to cream at the base; the supporting stem of each cyathium is known as the peduncle. Those of 'Fireglow' are—surprise!—bright raspberry. Immediately below the cyathia are several layers of the stem's terminal leaves, which are brightly colored when the flower cluster is young, not the green of normal leaves farther down the stem. The topmost whorl of these colorful leaves—known as bracts—is almost solidly orange; tips of the leaves in the layers below are blushed more and more fully with green. Between the top and second layer of these colorful leaves is a second and more sparse ring of pink-bracted cyathia. Below that, smaller clusters of cyathia can emerge from upper leaf nodes.

 

As if this detailing weren't sufficient, the floral display of Euphorbia griffithii is particularly quirky in that the young cyanthia are not held erect. Instead, they rest indolently on the colorful bracts beneath them. Their raspberry-colored peduncles are in great contrast to the orange bracts beneath them; the peduncles' slenderness and unusual length also maximizes the visibility of the bracts. Further, bracts enclosing each individual cyathium are held more closely to the male and female flowers than usual, creating a floppy cone instead of the usual flat sun-facing display seen in, say, poinsettia or crown of thorns. It's the lower surfaces of these cyathium bracts—known as cyathophylls—that are on display when the cluster is young. Lastly, at the center of everything—the axle of the entire radiating wheel of cyathia and colorful leafy bracts—is often a solitary stalk bearing a pair of nectar glands: An amuse bouche for visiting insects, before they settle down for the pollen and additional nectar that is available in the cyathia.

 

As the cluster matures, the cyathia become more erect as well as open, and their cyathophylls now display their orange (with pink veins!) interior as well as their exterior, which remains pink. But by now the orange of the large leafy bracts, alas, has faded to green. The overall amount of perceived bright coloring, then, stays about the same. 

 

its Fall foliage? In cool-Summer and Mediterranean climates (think the United Kingdom, or coastal California northward to Seattle), 'Fireglow' is described as displaying fiery Fall foliage. Perhaps due to the higher heat and humidity of Midwest and East Coast gardens, plants in those locales are reported to go dormant entirely by mid-Summer. I'm struck that I don't recall either performance in my colony here in southern New England. I'll observe more closely this season.

 

its affection for water: Many Euphorbia fail at the cold end of their hardiness range because their chosen sites can't provide the sharp drainage they require to overwinter. Euphorbia griffithii 'Fireglow' (and all of its cultivars that are not& formed via hybridization with other Euphorbia species that demand dry soil) not only tolerates soil of average moisture and drainage, it revels in the same rich soil and plentiful moisture that you'd otherwise favor with choice woodlanders such as Darmera, Deinanthe, Glaucidium, Podophyllum, or Syneilesis. In short, Euphorbia griffithii is, itself, a choice woodlander. See "Variants," below.

 

its imperviousness to most browsers: As is typical of Euphorbia, all parts of the plant are poisonous. Plus, the sap is unpleasantly sticky.

Flowering season

Mid-Spring into Summer.

Color combinations

The color palette of 'Fireglow' is complex—pink, raspberry, yellow, green, and orange—and yet, despite what would otherwise seem certain cacophony, the effect is lush, confident, and engaging. At any distance, the display reads as orange: The upper leafy bracts are orange, and are perceived as predominating petals, with everything else (the cyathia with their smaller bracts) as subsidiary "other stuff." After the display is mature, and the bracts have subsided to green, the orange inner surfaces of the cyathia become prominent. The quotient of orange, then, stays fairly constant. Unless your setting is intimate, handle 'Fireglow' as if it were just orange, and combine with other shades of orange or orange-red. Ebony and burgundy are the universal mixers, which would also be welcome. Purple or cherry red—red mixed with blue, in other words—would be anathema, as would be blue itself.

 

If your display ensures that 'Fireglow' will be appreciated at closer range—and, given the eccentric and energetic detailing of its flowers and bracts, anything less would be a shame—you could introduce other plants that call out to the colors of 'Fireglow' that reveal themselves only as you allow yourself to linger, to explore this plant's changing presentation of yellow, orange, pink, and raspberry details. I recommend that these more subtle relationships be well-calibrated: Don't choose a plant with merely pink (or yellow or cream or raspberry) flowers; choose one whose shade matches its intended 'Fireglow' detail exactly. See "Plant partners."

Plant partners

The Spring-into-Summer show of 'Fireglow' is complicated, with different colors of its adventurous palette highlighted at different times during its flowering cycle. The early show of pink stems and green flowers changes first to the early flowering of orange bracts, raspberry peduncles, and pink-backed cyathophylls, and then to the mature flowering of green bracts and orange-and-pink cyathophylls.

 

Depending on whether or not your garden can provide the even moisture 'Fireglow' needs to thrive in full sun, you may need to restrict its use to part shade. Your choices for partner plants, then, will differ dramatically due to their need for a particular exposure as well as, above, the timing and coloring of their displays.   

 

Because the intricacy of the details of the 'Fireglow' display are a constant even as the details themselves change, choose partner plants whose details are contrastingly simple, large, or both. Let 'Fireglow' supply the minute wonders of shading from this hue to that, contrastingly colorful veins, and, above all, weird floral anatomy. 

 

If you can establish 'Fireglow' in full sun, have the budget for annual plantings of tulips, and your resident wildlife won't eat the bulbs, they might be the ultimate seasonal partner to 'Fireglow'. Choose mid- or late-season cultivars in whatever solid colors best match the hues of 'Fireglow'. If your full-sun site also has impeccably draining soil that is, nonetheless, also moisture retentive, you might be able to please both 'Fireglow' and the apricot shades of Eremurus, such as 'Cleopatra' or 'Orange Marmalade'. Constructing a bed that is broad as well as deeply dug and high mounding might be the trick.

 

Although the flowers of Papaver orientale barely last a week, what a show the 'Ziermohn' cultivar would provide: Its melon-orange flowers seem just the right shade. Bearded iris are another herbaceous possibility. Although their flowers are complex and, usually, multi-colored, the range of colors is so broad that you can plant cultivars that lock in several of the 'Fireglow' shades at once. Look first among 'Brilliant Disguise', 'Fire Coral', 'Golden Panther', 'Magical Glow', 'Orange King', 'Prairie Sunset', 'Solar Fire', and 'Tennesee Vol'.   

 

Continuing with the full-sun fantasy, the orange-tinted young foliage of Spiraea japonica 'Goldflame' might match the young bracts of 'Fireglow', while the scary pink flowers might harmonize with the backside of the cyathophylls. If not, this shrub is inexpensive as well as tolerant: Rip it out or transplant it.

 

More likely, you'll find it easier to keep a colony of 'Fireglow' for the long term if the exposure provides some shade. Yes, that rules out the tulips, the eremurus, the poppies and iris, and (perhaps thank goodness) the spiraea. But the bronze young foliage of Rodgersia pinnata would be dramatic and complementary, as would be the orange-bronze-pink young fronds of Dryopteris erythrosora 'Brilliance'.

 

Perhaps no perennial that thrives in part shade as well as full sun offers as striking a match as some of the cultivars of Heuchera. 'Marmalade'? 'Peach Flambe'? 'Ruffled Peach'? There is such a range that you can (and will need) to choose cultivars are likely to favor your particular combination of heat, humidity, sun, and shade.

Where to use it in your garden

The display of 'Fireglow' is bright and sizable enough that the plant could be used in large-scale settings, where its broad mounding profile studded with large terminal clusters of bright orange "flowers" has a solid and shrubby character. But why not just plant an azalea instead? Many are in flower at the same time, but few have flowers that are as intriguing or downright bizarre as those of 'Fireglow'—provided that you can enjoy them at close-range. Either site 'Fireglow' towards the front of larger plantings, or provide a more intimate context in which this perennial can be focal, not just filler.

 

'Fireglow' peaks in mid-Spring, and its habit and texture, let alone the details of its floral display, are all distinctly different than those created by more-often seen Spring shows of bulbs, wisteria, hellebores, peonies, oriental poppies, and early iris and roses. If you can provide the consistent, season-long moisture it requires, 'Fireglow' is a welcome contrast with all of these full-sun stars. An even more striking look is to add 'Fireglow' to a bed full of classic shade- and moisture-lovers, where the presence of any Euphorbia, normally such a desperately sun-loving crowd, will be shocking, not just collaborative. Happily, most of them are peaking at the very same time as 'Fireglow'.

Culture

As is sometimes the case for Euphorbia species that are native to Tibet and Nepal, E. griffithii needs conditions that are in stark contrast to those native to the Mediterranean, Africa, Mexico, the Caribbean, and South America. These latter (such as Euphorbia tirucalli, E. cyparissius, and E. millii) all prefer excellent drainage; the subtropical and tropical forms usually require it. They are happiest in full and hot sun, and don't mind soils that achieve excellent drainage by being difficient in humus and replete with sand and gravel.

 

Euphorbia griffithii requires average to rich soil, and thrives in part shade, especially if this enables colonies to avoid being stressed by drought. Only in cool-Summer climates or in soil that remains moist all season long should it be sited in full sun. Euphorbia palustris (native to both Europe and Asia) is an even greater surprise, in that it thrives in soils that are permanently wet. 'Palustris' is the giveaway, meaning "of marshland." It will even grow in shallow water. So-called marsh marigold, Caltha palustris, is also appropriately named: It does best when growing in shallow water.

 

Other species of Euphorbia that enjoy the same woodland conditions as E. griffithii include E. schillingii and E. sikkimensis. I hope to establish them, too.

How to handle it: The Basics.

Plant in Spring, ensuring enough moisture for establishment. Allow stems to form fully, without pinching: Not least, the sticky sap is a mess but, also, this plant's wand-like stems aren't improved by attempting to encourage flower formation on stems that have been pinched in hopes of producing denser growth via additional and more substantive side-stems. If reduced height is desired, grow E. griffithii 'Dixter', which is reportedly more compact.

 

Do not dead-head. If female flowers are successfully pollinated, they mature to oddly-showy green fruits the size of peas, which protrude with almost embarassing pride from the remains of the small male flowers that were at the base of the female.

 

Allow stems to mature naturally. Depending (apparently) on the coolness of your Summer, this may be in Summer or Fall, and may be accompanied by a vivid display of red Fall foliage. Cut stems off at ground level after frost has killed them, by which time they will no longer bleed any of the pesky sap. If you want, delay this clean-up to late Winter; just be sure to finish before the colorful tips of new stems emerge in Spring. 

How to handle: Another option—or two!

None.

Quirks and special cases

From its comfort in shade and appreciation of rich soil and moisture, to its pink emerging stems, to its floral display, which is complex even for a Euphorbia, 'Fireglow' is quirky from top to bottom.

Downsides

The irritating sap is at best an inconvenience and, at worst, a real hazard. Avoid cutting Euphorbia griffithii during its growing season. See "How to handle it," above.    

Variants

The coloring of the bracts of Euphorbia griffithii 'Dixter' is reported as being darker, and the plants more compact than 'Fireglow'. 'Fern Cottage' has similar coloring, but is taller than 'Fireglow'. To my eye, it would be difficult to tell these three apart if they weren't growing near one another, so their subtleties of coloring, and the larger detail of their differing heights, were more obvious. 

 

'Jessie' is a hybrid of Euphorbia griffithii and E. polychroma. It has the height of E. griffithii, and the coloring and requirement for sun and—especially in Winter—excellent drainage of E. polychroma. The cyathium bracts are pure yellow with a thin red edge; the leafy bracts below are also yellow with the red edge, but lower ones become increasing blushed with green. 'Jessie' grows four to five feet tall, and is on my wishlist. 'Autumn Sunset' is another hybrid of the same parents, with orange bracts and comparatively compact height, two to three feet. Like 'Jessie', it also requires sharp drainage, especially in the Winter.

Availability

Online as well as at retailers.

Propagation

By division in Spring. Unusually for a cultivar, 'Fireglow' also comes true from seed.

Native habitat

Euphorbia griffithii is native to Tibet and southwest China. 

 
 
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