A Gardening Journal
Today in the Garden of a Lifetime: Stinking Hellebore in the Snow
- Published: February 06 2017
Winter in New England makes wise gardeners thrilled with details that might scarcely be noticed in warm weather. Here's a hellebore bent down beneath heavy snow—and it is so worth noticing. Not least, it's alive! Even more startling, being snow-buried doesn't appear to be causing it any distress. If this plant could talk, it would say, "I'm doin' great, and—since I know it's on your mind to ask—I just love this weather."
The snow makes the red petioles—like slenderest stems of rhubarb—even more visible; they are tipped by ferny palmate leaves.
The lighter-green leafy growth at the tips of the stems is unlobed and—can it be, in early February?—hiding fat round flower buds: this plant really is comfy in the cold.
The so-called stinking hellebore usually eases into bloom in late winter or even spring, so early February is early indeed. So far, the winter has been mild; perhaps to the plant, it feels plausible that spring itself is imminent. It's more likely that there isn't a rush into spring bloom at all because, for a hellebore, the return of cold weather isn't a problem. In fact, it doesn't matter when or even if true spring arrives: hellebores are opportunistic growers during the cold months. For them, it's normal to make progress between episodes of freezing weather; growth will resume the next thaw, so there's no problem that this freeze—and the next, and the ones after that—has arrived.
Several challenges must be addressed for this lifestyle to be successful.
First, even the youngest, newest growth—that just formed during the last thaw—must be resistant to freezing even when temperatures themselves fall below freezing. Helleborus foetidus is typically hardy down to ten degrees below zero Fahrenheit; some sources say that hardiness down to minus fifteen or even twenty is possible. Water freezes at thirty-two degrees above zero, which means that forty degrees colder than freezing, this hellebore's stems and leaves—and even its just-emerging flowers and buds—will likely still not be damaged. When milder weather returns, even this most fragile new growth simply resumes activity.
Clearly, cells and veins of hellebores are heavily spiked with natural antifreeze!
Tolerating intense cold isn't the only challenge of growing vigorously when most other plants are leafless and dormant. Hungry browsers are about, and with fewer choices than in warm weather, there's increased risk to what little leafy growth is around. All hellebores handle this threat by being poisonous from root to flower: exploratory nibbling isn't likely to be repeated. Helleborus foetidus employs the additional strategy of emitting an unpleasant smell when growth is bruised or broken; the species name—meaning stinky or rotten—is apt, if a bit of an exaggeration.
Creating and sustaining vegetative growth during the cold season is just one achievement. Coming into bloom when severe cold and clump-burying snow are possible necessitates further quirky adaptations. The flowers had better be long-lasting, and for two reasons. First, they need to survive, say, a blizzard that blankets everything with two feet of snow that doesn't melt for six weeks. They do. In fact, being buried outright by snow is always good news for hellebores: if the weather is cold enough for heavy snow, at least it functions as protective mulch, shielding the clump from damage from the cold winds that rage in the open air above the snowpack.
Second, what are the pollinators for those flowers? Remarkably, they are all cold-blooded insects—bees, chiefly—not warm-blooded birds or small mammals. But insects are especially incapacitated by weather that's chilly, let alone well below freezing. So hellebore flowers also need to be able to stick it out during days or even weeks of freezing weather and "snow burial" to be ready for pollinators that, come milder weather, can once again become active. Handily, the very cold that could bury the hellebore with snow as well as restrict pollinators to their sheltering nests also keeps the hellebore's reproductive growth fresh. Think of it as natural refrigeration.
But still: success of this unlikely combination of growth that is thoroughly antifreezed and highly poisonous, flowers that are strikingly long-lasting, and pollinators that are only active above freezing would seem slim on the face of it. Wouldn't it be more effective to ditch all of these cold-weather heroics by flowering in May and setting seed in June and July?
The hellebores' native habitat provides clues why this grow-when-it's-cold strategy is better. The species are all native to mountainous areas of either Europe or Asia; H. foetidus is specific to central and southern Europe, Greece, and Asia Minor. While cold temperatures in winter are to be expected there, so are more lengthy intervals that would strike North American gardeners as being quite balmy and spring-like. Plus, in these native locales, winter and spring are the seasons of more plentiful moisture, followed by summer's intense heat and, often, drought. Even though the cool seasons are sometimes paralizingly cold, those low temperatures are ephemeral—merely an interruption during months that are otherwise excellent for germination, growth, and reproduction.
This perennial's tolerance of occasional severe cold also provides unexpected endurance where winter weather is both cold and tenacious. When ambient temperatures are below freezing, so is the plant's growth; hellebores are not warm blooded! The plant's experience is similar to that of a human undergoing anaesthesia or, perhaps even more comparably, in a coma. The loss of consciousness (for the human) and general activity (for the plant) could be minutes, days, or weeks, after which awareness and activity can resume. I can vouch that, regardless of the actual length of anaesthesial unconsciousness, to the affected person it seems a blink of an eye: one moment one is still awake and—even though the actual passage of time has been hours—seemingly the very next moment one is reawakening. Animal or plant, if there's the ability to lose functionality temporarily but regularly, and then regain it and continue with life, the length of any one "outage" might not be important.
And so, because hellebores can withstand below-freezing temperatures even when at the height of flowering, it doesn't matter whether the freeze lasts just the night or for weeks on end. It also doesn't matter if this freeze is followed by others. Whenever temperatures next moderate, the life cycle will continue. From the hellebore's vantage, then, it doesn't matter if the frigid interim was just a day or two in January in Macedonia, followed by springy weather—or eight weeks of snow and ice in Maine, followed by four or five more.
Another possible advantage of cold-weather flowering helps address the rare hellebore shortcoming: while hellebore flowers, foliage, stems, and roots are all poisonous, the seeds are edible. (So are the flowers' pollen and nectar, lest pollinators be killed off. Remember that pollinators aren't intentionally pollinating; they are merely foraging for food, and find it while rummaging energetically among the various parts of flowers.) One source cautioned that rodents need to be kept away from Helleborus foetidus clumps because they forage fallen seeds and even harvest them from the ripening flowers. Tellingly, another stresses that the seeds need several months of cold to germinate, and typically sprout between November and March.
Seeds formed during winter and early spring, then, wait out summer before germinating in fall and winter. Rodents are somewhat less active in cold weather, while seeds that fall onto the leafy woodland soil surface that this hellebore favors are likely to be out of sight all summer. Plus, summer can be so dry in this hellebore's native locales that germination and establishment of young—and, therefore, still shallow-rooted—plants is likely to be more successful when moisture is more plentiful. If that means awaiting the return of rains in fall and winter, so be it.
I'll revisit this stinking hellebore when it's in bloom, and will provide the full How To Grow It chart then.
Here's how to grow Helleborus niger 'Thankgiving', which also maintains a vigorous presence in the garden in winter regardless of the severity of the weather.
Here's how glad-to-see-you Helleborus niger is even when flowering during persistent snowfall.