A Gardening Journal

The Best Season Ever: Miss Willmott's Ghost

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When Miss Willmott's ghost is going gangbusters, the garden is automatically at a peak. Sometimes—as here—all it takes is a single plant. In the picture below, you can just see a portion of the single stem that ramifies into the sparking bushel-basket-sized display atop it.

 

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About the "flowers." Each true flower is one of the hundred or so white tufts on the cob-like structure below. The cob's base is ringed by a sensational ruff of mercilessly sharp-pointed bracts, which are modified leaves, not petals. (Thank you, FrustratedGardener.com, for this crystalline close-up. Click on the version at the site; its depth of resolution is staggering.)

 

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The picture above also shows that the intensity of the bracts' silver can vary. My experience is that in less than full sun, more and more green creeps in. In the picture below, a "ghost" volunteered in the half shade of my beech tree, but still managed to flower. The bracts are greener still, but thrillingly so.

 

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In the full sun the species prefers, bracts have the striking matte-metallic whiteness shown in the picture below.

 

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Eryngium giganteum is a fearless self-seeder, and will spread all over a garden as long as it can find plenty of sun and soil that is at least reasonably drained. Sandy or gravelly sites are at particular risk of being overrun. The solution is to deadhead diligently. Cut off the entire stalk, not individual "blossoms," even before they get to the half-brown maturity below. Then you're assured that they haven't yet produced viable seed. Plus, stems cut at their peak are stunning in a bouquet.

 

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The foliage of Miss Willmott's ghost is the species' one blah note: leathery green leaves in a loose basal rosette that wouldn't merit a second glance if you didn't know the floral drama to come.

 

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Any given rosette usually lives just portions of two consecutive calendar years—from Spring of the first to mid-Summer of the next. Late-starting seeds are liable to produce plants that need the entire second year to build up a head of steam before starting into flower in early Summer of the third.

 

Whenever it happens, the flowering is the beginning of the end for that particular plant, which sets seed as quickly as it can, then dies. As long as you leave a single ripe (i.e., all brown) cob here and there, you've ensured that there are plenty of Eryngium giganteum seeds to carry the species on.

 

 

Here's how to grow this striking, easy biennial:

 

Latin Name

Eryngium giganteum

Common Name

Miss Willmott's ghost; giant sea holly.

Family

Apiaceae, the Carrot family.

What kind of plant is it?

Hardy biennial or short-lived perennial, living just two or three years at the most. Monocarpic: No matter how long it does live, it flowers just once—spectacularly—then, promptly, sets seed and dies.

Hardiness

Zones 4 - 7.

Habit

A solitary basal rosette of foliage matures to produce an erect, single, thick flowering stalk that bears multitudes of tiny flowers, grouped tightly into many cob-like structures as thick as your finger and an inch or two high. Each cob is surrounded at the base by spiny stiff bracts that (in full sun, at least) are a silvery white so intense that they seem as much mineral as vegetable.

Rate of Growth

Fast in at least two senses. In a long-season climate, and with ideal circumstances of sun, heat, soil, and drainage (see "Culture," below), one season's seeds may have time to germinate and grow into young plants that by Fall can achieve sufficient size to be able to flower the very next Spring. Then there would be a fresh crop of Miss Willmott's ghost in full flower every season.

 

In any given season, it seems a short time—just weeks—from when the emerging flower stem is first evident to the triumph of the tall, thickly-branched candelabrum in full flower.

Size of the rosette—and then the plant in full flower

The basal foliage isn't likely to form a rosette much more than a foot across or high. As with many biennials (think hollyhocks), the flower stalk it produces at maturity is surprisingly large, with sturdy side branches extending as much as a foot out from a central stem that can lengthen to anything from a foot or so, to four or five feet tall. The shortest stems result from crowding, as when you've let your eryngia self-seed completely and didn't even thin out the seedlings—or when water and soil nutrients are both scarce. The tallest stems are nearly always a result of soil that's too rich and overly moist. See the "Culture" and both "How to handle it" boxes for details of growing Eryngium giganteum with flower stalks that are the height you need. 

Texture

As a soloist, an Eryngium giganteum in full flower can have substantial focal and even architectural presence. This is only somewhat from the stem's potential height of two to five feet. The bract's spiky and spiny texture, and the lack of much foliage (they are bracts, actually) on the thick flower stems also contributes to the impression of strong, open, and nearly arboreal vigor.  

 

If Miss Willmott's ghost is used in groups, the effect is nearly opposite. Then, the side branches of one stem tend to mingle with those of its near neighbors. Plus, the ruff of large bracts that surrounds the central cob of tiny blooms will look to most viewers like a single flower the size of a large daisy or a rose. Further, plants in a given group tend to produce flower stems of similar size, because stem height is related to growing conditions more than individual variance, and those conditions are likely to be similar across that group. With comparatively large "flowers" arrayed on interlocking branching stems that hold them more or less within a narrow range of heights, the overall look is of a densely flowering mound within which individual plants or flowering stems are barely distinguishable. 

Grown for

its bracts: The true flowers are tiny and, while they are arrayed in a tight cob that's thumb-thick and up to a couple of inches long, this species' glory is the ring of bracts at the cob's base. They are extravagantly lobed; each pointy prong is stiletto-thin and nearly as sharp: You'll only have an incautious encounter with the bracts once. When plants grow in their preferred full sun, the bracts are heavily overlaid with an intense silvery white. (From the other vantage, they could be seen as being underlaid with an icy sea-green.) Plants growing in less than full sun don't flower nearly as well, but the bracts are, if anything, even more interesting: The silvery white is restricted to the center, the veins, and the thinnest outer edge, with the rest being forest green.

 

its self-reliance and vigor. Eryngium giganteum thrives in poor dry soil and blazing sun, where it can self-seed with abandon. In these circumstances, the species can quickly become far too much of a good thing. See "Downsides," for practical suggestions for control. In gardens with regular soil and moisture, the ability to self-seed is lessened but not eliminated.   

 

its imperviousness to browsers: The tiny flowers are favorites of pollinators, but the rest of the plant is apparently a turn-off. The fierce bracts are just the beginning. The thick flowering stem is armed with more of those same bracts, so is unlikely to be chewed, especially when just emerging. The leathery basal leaves are soft and unguarded but, in my experience, are also untouched. Ironically for this member of the carrot family, not even the taproot is tempting. If its bracts were less showy or even absent, this species would still be worth growing, especially in gardens that need to welcome the full complement of local fauna.

Flowering season

Early to mid-Summer: In my garden, late June into July. By August, it's high time to cut the flowering stalks to the ground. In climates that are milder and warmer—Italy, say—flowering probably begins earlier and, alas, ends sooner. In climates that are milder but cool—Great Britain, say—the flowering season is reported to extend into August. Lucky them! I'm not aware of any tactics that can delay flowering until later in the season, or extend the performance once flowering has begun.

Color combinations

The gray-blue of the tiny flowers is discernible only at extremely close range; it's the silvery white of the bracts that is predominant.

 

Eryngium giganteum is a natural in any pastel-friendly context. The bracts can also work with more vivid hues, but the juxtaposion of silvery white with, say, indigo or acid yellow or scarlet can be jarring if there aren't additional details to mediate. Easiest is to have the plant that is supplying the vivid colors also feature notes of silver or white. Can its bright flowers have white pistils or stamens, or a white edge to their petals? Or is there a white-variegated foliage form, not one whose leaves are solid burgundy?

Plant partner

Because Eryngium giganteum forms the tallest, branchiest, and most floriferous stalks when growing in full sun, you need to ensure that the modest rosettes aren't hidden and, therefore, shaded during the full growing season they need to gather strength for their spectactular flowering the next year. Then, after the flowering stalk has begun to emerge, flowering seems quite unstoppable, so a certain amount of dappled shade during that same year will have little effect. But still, there's the rosettes' long and fairly boring adolescence that needs to take place, as it were, while they are completely naked and in full view.

 

In this regard, Eryngium giganteum is nothing like some other biennials such as Verbascum densiflorum, Onopordum acanthium, and Heracleum sosnowskyi, whose displays of foliage each have substantial appeal. Come to think of it, both the Verbascum and the Onopordum would be terrific companions for the Eryngium. Their unusually high-flying flowers would likely be far overhead, but their immense fuzzy foliage would create a huge backdrop for the rosettes. Similarly, although the Eryngium is hardy only as warm as Zone 7, Buddleja nivea is hardy as cold as Zone 7, so the two could be grown together. The white-felted stems and leaf-backs of this unusual species of butterfly bush could harmonize well with the painfully sharp and stiff whiteness of the Eryngium.

 

To get the best floral display from your "ghosts," you need to accept and even embrace the display of basal foliage the year before. The leaves have some shine, and they remain in good condition. Could woolly thyme be established nearby? It is prostrate, so casts no shade. And its dense fuzzy leaves could form a striking carpet for the (by comparison) huge Eryngium foliage  high above. Hieraceum pilosella would work also. Its fuzzy mouse-ear leaves are absolutely prostrate, and are at their most silvery in the lean conditions Eryngium giganteum prefers.

 

Associating "ghosts" with vividly-colorful neighbors works best when those brighter plants also include a clear reference to the chilly tones of the Eryngium. When possible, choose vivid partners that also have flecks or even dashes of white or silver. Perhaps three young plants of Euphorbia cotinifolia could be planted as annuals near or even amid Eryngium rosettes that had become well established the prior year. The euphorb's garnet-red foliage is a thrilling but also "blunt edged" contrast to the chilly tones of the Eryngium flower stalks that should emerge this season. But the tropical plant's tiny flowers are a just-as-chilly white. Some cultivars of Buddleja davidii could mingle exuberantly with the Eryngium. 'White Ball' is a dwarf whose flowers are pure white, and whose willowy leaves echo the sea-green of those of the Eryngium. 'Ice Chip' is a complex Buddleja hybrid, with B. davidii as just one of its several parents. It also has white flowers and, at just two feet tall, is even dwarfer than 'White Ball'. Plus, it's sterile, so there's no danger of volunteers.    

 

Because each bract-surrounded cob reads as a single large flower—and a single stalk could boast several dozen of them—an Eryngium giganteum can have the "big flower" presence of a hybrid tea rose. If flowering is a major aspect of partner plants, choose those with blooms that are much smaller and, ideally, held in loose and airy sprays. Euphorbia corollata isn't called native baby's breath for nothing. The tiny lavender flowers of Verbena bonariensis are in dense clumps, but they are small, and borne on plants that have impossibly few leaves but many thin vertical stems, through which the silvery-white big-blooming bulk of the Eryngium will shine.

 

Going the verbena one better, consider associating Miss Willmott's ghost with ornamental grasses. There are many that also crave sharp drainage and plenty of sun. Their erect slender stems, narrow blades, feathery flower and seed plumes, long peak season beginning in Summer, and range of pastel hues in seeds, stems, and leaf blades, all make them near-perfect companions. Plus, they permit a decent amount of sun through their growth, even when the sun is low in the morning and late afternoon. And their billowing habits makes the late-season absence of the Eryngium (which should be all dead and cut to the ground sometime in August) nearly invisible. Consider Bouteloua gracilisEragrostis spectabilis, Panicum virgatum (at the backside of the Eryngium only), Schizachyrium scoparium, and Sorghastrum nutans.

 

Narrow stems, in fact, could be the fail-safe textural theme. The forsythia-yellow flowers of Genista lydia emerge all at once in Spring; by the time the ghosts's flowers are done, this shrub is a horizontal mass of sparse, narrow green leaves and slender green twigs.  

Where to use it in your garden

Eryngium giganteum is easiest to incorporate when some (but not all) of the self-sown plants are allowed to pop up amid more permanent plantings. The basal rosettes of foliage are not showy on their own, and soon after each has matured to flowering, the entire plant dies. Because of the tap root, plants usually resent disturbance and, so, would be a challenge to array intentionally in a more carefully planned design. True, you can easily transplant seedlings to form larger groups, but then you would be looking at a group of boring small-then-medium-sized rosettes for an entire season, or even two.

 

Because plants are particularly fond of establishing in areas of gravel, why not welcome a scattering of Eryngium giganteum to walkways or driveways? It would be worth it to plan for its presence by making such areas large enough to accommodate the occasional volunteer without also limiting easy passage.

Culture

All possible sun, and any growing medium that provides average to fantastic drainage. Eryngium giganteum thrives in soil that is so lean and fast-draining that to call it soil seems an overstatement: Loose gravel spread on driveways or walkways, beachfront gardens and even dunes (the other common name of this prickly plant is sea holly), cracks in ledges that would seem to contain little but small gravel and some trapped decaying leaves, interstices in dry-laid paving. In each of these spartan settings, Miss Willmott's ghost is likely to establish and flower.

How to handle it: The Basics

See "Propagation," below, to get started on growing Eryngium giganteum from seed. Young plants develop a tap root so quickly that they need little if any supplemental watering. As long as you site them so that they receive as much full sun as possible, you can let them grow on their own.

 

Plants that germinated in Spring of the previous year may well have been able to develop enough through that Summer and Fall to flower in Summer of their second season. If not, the next Spring and Summer for sure. Plants from seed sown in Fall are almost certainly going to need a full intervening year for rosette growth before flowering the next Summer. In other words, the total lifespan of plants sown in Spring could be as little as sixteen months; that of plants sown in Fall is more likely to be about twenty-five months.  

 

At any age, rosettes are not so large that in late Fall they are likely to need clearing away of dead foliage.

 

Mature rosettes indicate that flowering is imminent by producing what at first looks like a stemless, spiny, very ruffly green-and-white rose at their heart. This is the developing flower stalk, which is protected as it emerges by the same sharp-pointed bracts as will soon ring the flower cobs. As the flowering stem elongates, the bracts become spaced farther apart. Developing flower stalks normally need no intervention; just let the show take shape.

 

After peak flowering has passed, the cobs will turn brown ahead of a similar transition for the bracts. If you'd like more seedlings, clip a couple of all-brown cobs and set them on the ground where you'd like to establish other colonies. To reduce the amount of unwanted self-seeding, don't dawdle about cutting the flower stem itself to the ground. Have a large black contractor bag handy, so you can clip off and then compact each spent stalk right after you've placed it in the bag. If you compact a stalk while it is still en plein aire, you'll likely help release hundreds of ripe seeds. If your goal is to collect seeds, not just remove them from your garden, every so often empty out the detritus from one bag into another. All of the inevitable jostling and crunching will have released loads of seeds, which will be nicely collected at the bottom of the first bag. Trickle them into a smaller separate container (a jar, or a can with a resealable lid), to free up the first contractor bag for another round of the collection cycle.

 

Unless you are able to maintain a much higher level of tidiness in your garden than I am, there's no need to pull up the rosettes you leave behind after the stalk-clipping. They die on their own soon enough. If you must yank them, wait until they are fully dead, by which time their roots will have already released much of their grip down into the soil.

How to handle it: Another option—or two!

Unless your garden is exceptionally damp, shady, and poorly-draining in Winter, chances are that there will be a few places for Eryngium giganteum to settle in for the long-term. With the security of a steady supply of seeds and small transplantable seedlings, you might explore attempting to establish other colonies in varying amounts of shade, to see if there's a sweet spot of enough shade to cause production of the unusual green-and-white bracts, but not so much as to preclude flowering entirely. Any shade at all will decrease the size and floriferousness of the bloom stems but, if anything, this could be seen as making the green-and-white bracts all the more desirable on account of their greater scarcity.

 

Eryngium giganteum prefers the lean life; if circumstances are too rich and moist, taller and taller flower stems can result. These are ultra-dramatic for massive arrangements, but can be floppy in the garden. Fortunately, the density and side-branching of flowering stems also makes them easy to stake, because those side branches hide the stake while also providing plenty of anchoring growth through which the stake can be plunged. As with growing Miss Willmott's ghost in part shade to encourage more green-and-white variegation in the bracts, growing the species in richer and richer soil should establish just how tall the resultant flower stems can be before the soil is so juicy that the rosettes rot over the Winter. If ever there were a need for that ultimate soil fantasy, "rich but well-drained," it would be for growing such competitively-high stalks of Eryngium giganteum

Quirks and special cases

Eryngium giganteum can be thought of as giant in a couple of ways. First, the cob of tiny flowers is notably larger than that of almost any other Eryngium species. And, while the basal foliage rosette isn't notably large, the flowerstalk arising from it is unusually taller. Among Eryngium species hardy to at least Zone 6, only those of Eryngium yuccifolium are regularly taller; they can reach five feet and higher.

 

The true giant of the genus, Eryngium pandanifolium, isn't hardy colder than the milder portions of Zone 7. This species is a perennial, not a biennial, and its clumping basal foliage can mound to three feet high and five feet across. Its spiny leaves are shaped like narrow swords, and will remind most readers of the leaves of pineapples. (The leaves of screw pines, in the Pandanus genus, are an even closer match.) Flowerspikes can top eight feet, and can hold hundreds of flower "cobs." The cobs are much smaller than those of Eryngium giganteum, as are the bracts.

 

Miss Willmott, let alone her ghost? Ellen Willmott was an enormously wealthy horticulturalist who lived from 1858 to 1934. Judging from the round numbers bandied about—"she grew 100,000 species of plants"—her estates in Britain, France, and Italy must have been stuffed. Both her British estate (Warley Place) and her surname find their way into scores of cultivars and species named in her honor, Epimedium x warleyense, Ceratostigma willmottianum, and Corylopsis willmottiae among them. She was reported to carry seeds of Eryngium giganteum with her when visiting gardens, to sprinkle them around on her own initiative. (Ah, the presumptuousness.) The next season, the plants' strikingly pale bracts would show up beautifully, especially after dusk, when a ghost would be more likely to enjoy a garden stroll. 

Downsides

On more than one occasion, I have had clients protest that Eryngium giganteum is too prickly. They have a point (so to speak): The tips of the bracts are needle-sharp. Don't plant Miss Willmott's ghost so close to pathways that the bracts could prick the skin of unsuspecting passersby. 

 

Even in my garden, where drainage can be poor and the soil is rich and heavy, Eryngium giganteum can self-seed with abandon. Even an inch or so of loose gravel atop who-knows-how-winter-wet soil seems to be an acceptable spot for volunteers. While the mature flower stalks do have a spartan elegance in Winter, leave them in place only if your circumstances are such—muddy wet in winter, or shady at any season—that successful self-seeding is unlikely.

 

There's usually little need to extract unwanted plants, and their quick success at establishing taproots can make that a challenge anyway. Instead, take advantage of this species' appropriately silver lining: Eryngium has a short lifespan, and the flower stems are showstopping in a vase. Once a given rosette has matured to flowering, harvesting that stalk won't give that rosette another lease on life. It will die on schedule, of its own accord.

 

Have a friend who sells at a farmer's market? Donate your entire crop of excess flower stems. Because even a single stalk of Miss Willmott's ghost can make a stunning arrangement, the retail value of several dozen stems at the right Saturday market could be hundreds of dollars. 

 

View any excess plants of Eryngium giganteum, then, as the opportunity to have an extraordinary bouquet—or ten! It's hard to imagine a more beautiful (and generous) tactic to eradicate "weeds."

Variants

Eryngium giganteum is a favorite of florists, gardeners, and seed-houses alike, as well as horticultural gatekeepers such as the Royal Horticultural Society, which sells plants from its own website. For any species with such hearty commercial success as well as approval of the cognoscenti, it's puzzling that the existence of named cultivars is so confusing and, even, dubious. Seed houses often turn the common name, Miss Willmott's ghost, into a cultivar name, e.g., Eryngium giganteum 'Miss Willmott's Ghost'. (There really is a Miss Willmott, and she's one of horticulture's great eccentrics; see "Quirks," above.) But even sources that would eschew mere commercial temptation list cultivars, such as 'Silver Ghost', that seem indistinguishable from the straight species. In my experience, the intensity of the silvery display of the straight species of Eryngium giganteum grown in full sun is indistinguishable from that of any cultivar.

 

Even more confusing is that the representative picture in the various listings can vary. No matter that the identification is this or that cultivar or the straight species, the usual display—bracts that are silvery white—is sometimes omitted in favor of a picture showing flowers whose bracts are silvery white only towards the center, shifting to a slate green with silver veins at the tips. Further, the very existence of any stable cultivar of a plant that is famous for flowering once, dying, and reappearing as self-sown volunteers is unlikely on the face of it: Naturally-pollinated seeds typically don't come true.

 

It's more likely, then, that variances in pigment are due to exposure, not genetics. Plants growing in less than full sun (or, I suppose, in climates that are cooler or tend toward sustained cloudiness) produce bracts that have the green-and-white-veined tips. In full sun in any climate whose Summer days are hot, the bracts are usually an intense silvery-white.

 

If anyone can prove that self-seeding cultivars are stable as well as distinguishable from the species, I welcome the news.

Availability

Seeds of Eryngium giganteum are readily available online and also, in season and with pleasure, from gardeners who  already grow it: The more seeds they give you, the fewer will remain to self-seed.

Propagation

By seed. Scatter them atop open and well-worked soil whenever they become available. There is no need to cover them, or press them into the soil. Eryngium giganteum is highly successful at self-seeding: Seeds fall where they may, and that's that. The plant is quite hardy (to minus thirty degrees Farenheit), so seeds could even be scattered atop the soil when it has become covered by snow. Seeds scattered in Summer usually germinate and form small plants by Fall. Seeds sown later might wait out the Winter, to germinate in Spring. Seedlings quickly show the species' characteristic round, thick, shiny green leaves, so are easy to identify. Thin them to a foot apart, so that flower stems will be taller and more branching.

 

At least one source also suggests propagation from root cuttings in late Winter. Given the vigor with which Eryngium giganteum usually self-seeds, plus the uncertainty that any distinct forms truly exist and would, therefore, require vegetative propagation—see "Variants," above—root propagation sounds like a lot of bother.  

Native habitat

Eryngium giganteum is native to Iran and the Caucasus.

 
 
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