Hellebores Are Riding High
There would be little exaggeration if you said hellebores deserved a spot on the current hit parade of perennials. The rapid ascendancy to mainstream popularity has even begun to shake the pillars of the hosta world and its long-lasting claim to dominion over all in the shade garden.
Why are hellebores moving up so quickly in sun-challenged gardens? They flower in a wide range of colors from winter to early spring and also tolerate heat. They are long lived, low maintenance, and drought and deer resistant. Most commercially available plants are cold hardy from at least Zone 4 through Zone 9. In their native provenance of Southern Europe, the species experiences warm days and cool evenings, yet they have proven very adaptable, surviving even in the southern United States. Sound like a recipe for success?
Breeding Better Plants
The ordinary species — and even some of the earlier hybrids — did little to excite home gardeners. Besides lovely white flowers on the early flowering Christmas rose, Helleborus niger (December-March), and the reddish-purple blossoms of Helleborus purpurascens (mid-March to mid-April), there wasn’t much to tempt anyone among the early hybrids with the lenten rose, Helleborus orientalis. The drooping flowers in dull shades of chartreuse, pink and white were boring, but they were early flowering from late February until mid-April. And gardeners, hanging by a thread after months of endless cold and gray, responded to any blooms that boldly dared to face off with the remnants of winter.
Breeding work began in the 1960s, principally in England and Germany, and picked up steam over the last 15 years in the United States. Selection efforts accompanied by a better understanding of production techniques have produced more-consistent seed strains and better availability. The plants most commonly grown are known as Helleborus x hybridus and represent a stewpot of bloodlines between Helleborus orientalis and other species. Vast improvements in mixed flowering strains are represented by ‘Royal Heritage’, ‘Winter Queen’, ‘Select Strain’ and ‘Ashwood Strain’ from the United Kingdom.
Though seeding is still the predominant means of propagation, the tissue-cultured ‘Ivory Prince’, marketed by Skagit Gardens, has been a breakthrough success in vitro. It is the result of a complex series of crosses and opens the way for a new chapter in hellebores.
Breeders now offer seed-grown selections of Helleborus x hybridus in single colors of dark purple, red, pink, yellow or white. Jelitto’s Lady series produces these distinct colors more than 90 percent of the time. Semi-double and double-flowering forms are available in varieties like the white-flowering ‘Betty Ranicar’, Pine Knot’s Southern Belles and Jelitto’s ‘Double Vision’ and ‘Double Ladies Mixed’. Most breeders are infatuated with spotted or picoteed types. Some prefer upward-facing flowers while others like the charm of nodding, bell-shaped blooms.
Helleborus x hybridus selections receive most of the attention. The lesser known, earlier flowering Helleborus niger has gotten a bum rap for being fussy. I haven’t had any difficulty, though I have found them a little slower growing. In milder Decembers I can find blooms at Christmastime in my Louisville, Ky., garden. Cold snaps will delay bloom until a warm spell returns. Helleborus niger ‘Maximus’ has especially large blooms and ‘Praecox- Hybrid’ is earlier flowering, faster growing and well suited for container production.
Hellebrous foetidus, the so-called stinking hellebore, has lovely, more narrow leaflets than other species and clusters of small, chartreuse blooms. ‘Wester Flisk’ has greenish blooms with a reddish edge, and the seed strain ‘Gold Bullion’ has stunning golden foliage in winter, though in warmer summer climates the color will fade to green.
Hellebores have a lengthy seed germination timetable that may require 4-6 months, with an additional 4- to 12-month growing-on schedule. Despite the time investment, for many, seed-grown plants remain the most economical option for the foreseeable future. The germination process is not difficult but does require space and time.
Seeds must be sown soon after harvesting, between June and mid-August. When seeds are dispersed from their mother plants, the embryo is not fully ripened and does not fully mature for another 6-12 weeks (it is safest to presume 12 weeks).
In production, the warm-moist period required for seed ripening can be accommodated in the plug phase by planting in either deep (2 1/2 inches), open flats that are easier to oversee or in 72- to 228-cell plug trays that will need more vigilance to maintain even moisture. Natural autumn-winter cooling is the best way to allow for the necessary moist-cold stratification of 4-10 weeks. Variable temperatures ranging from 25-40° F are preferred over a constantly cooled, refrigerated period.
Hellebores are not members of the rose family, as you might imagine with common names of Christmas and lenten rose. Rather, they are members of the buttercup family, ranunculaceae. Unlike most seeds of herbaceous perennials, those of the ranunculaceae family can withstand gradually cooler temperatures to about 25° F, but you should protect sown flats from temperatures any colder.
Germination begins at 40° F and continues as the temperature gradually rises between December and April. Be careful not to raise temperatures too soon; simply allow the temperatures to rise naturally. Otherwise, a sudden temperature hike can kill young, emerging seedlings and send remaining seeds into another dormancy.
Transplanting into 1 3/4-inch deep, 72 cell or larger flats should begin at the cotyledon stage. The well-drained medium should include trace elements. Use a constant feed of 100-ppm nitrogen, 10-ppm phosphorous and 100 ppm of potassium for 3-4 weeks following transplanting.
Transplanting into a finished 4 1/2-inch (or larger) container can be done by late spring, early summer. A 13-13-13 slow-release fertilizer can be applied at a rate of one-half teaspoon per 4 1/2-inch container. Keep hellebores shaded with 50-percent shade cloth through the warm summer months.
Wet soil conditions — either in pots or the garden — tend to be the principal disease concern; hellebores cannot handle soggy media. Other than moisture-related problems, mustard seed fungus, Sclerotium rolfsii, can occasionally cause problems, especially in acidic soils.
Salable plants are ready in 8-10 weeks following final transplant. Flowering will generally occur the second year. Hellebores will grow from 15 to 20 inches tall and will reseed.
Because they are unfamiliar to most consumers, garden center customers often need sales suggestions for crops that work well with hellebores. Colorful garden combinations might include witch hazels, veronica ‘Georgia Blue’, pulmonarias, Cyclamen coum, toothwort (Dentaria diphylla), snowdrops, crocus and narcissus, plus the foliage of asarums, arums and heuchera ‘Dale’s Strain’. If you exhaust all other combinations, plant a hosta or two.
In spite of a lengthy production schedule, healthy profit margins are possible. And hellebores — perhaps because of this specialized production schedule — don’t appear destined for commodity pricing anytime soon.