April 2013 Culture

Perennial Solutions: Helleborus x hybridus ‘Ballerina Ruffles’ By Paul Pilon

Sixteen years. Although the popularity of helleborus has increased since the Perennial Plant Association selected Helleborus x hybridus as the 2005 Perennial Plant of the Year, Chris Hansen has been working diligently for 16 years hand-crossing and selecting helleborus searching for improvements in flower color, bloom size, foliage characteristics and plant vigor. His breeding efforts allowed for the remarkable new cultivar helleborus ‘Ballerina Ruffles’ to be recently introduced.

‘Ballerina Ruffles’ is a beautiful variety featuring large, fluffy 3-inch double flowers ranging from a light pink to bright lipstick pink coloration, some with purple speckling. This cultivar is marketed under the Winter Thrillers series, which contains eight additional cultivars of various colors as well as a mixture of the varieties in the series. ‘Ballerina Ruffles’ blooms for an extended period, retaining its color for up to 12 weeks.

Helleborus performs well in shady locations throughout USDA Hardiness Zones 4 to 9. At maturity, it forms attractive evergreen mounds of foliage, reaching 18 to 22 inches tall and 24 inches wide. With its colorful double flowers, ‘Ballerina Ruffles’ puts on an impressive display in the late winter to early spring. Helleborus are reliable, long lived, and low maintenance. Additionally, they are one of the few perennials resistant to feeding by both deer and rabbits.

Lenten rose can be marketed as houseplants which can be planted into the landscape, as container plants, or used in border or mass plantings in woodland or shade gardens. With its unique double flowers, early flowering, extended bloom time, ease of production and reliable landscape performance, helleborus ‘Ballerina Ruffles’ is one Lenten rose no perennial program should be without.

Propagation

Helleborus x hybridus ‘Ballerina Rose’ is propagated by seed, which is the result of hand crossing. The seed is F3 generation which means it’s true to color. Currently, seed is not available to commercial growers. Additionally, germinating helleborus seed requires stratification for germination, which can be challenging for growers to provide and requires more time than most growers are willing to offer for propagation. For most growers, it is most economical to purchase in finished plugs of helleborus varieties.

Production

Helleborus are most commonly produced in 2-quart to 1-gallon containers using large plug liners as the starting materials. It performs best in a growing mix with adequate water holding ability and good drainage; many bark-based growing mixes work well. Plant the plugs even with the soil line of the plug or container it was previously grown in.

Lenten rose performs well when they are grown under moderate fertility regimes when the plants are actively growing and light fertility programs while the plants are not actively growing such as during the summer dormancy. While the plants are actively growing (generally February through early June and again in September through November), growers can provide nutrients using water-soluble fertilizers delivering 100- to 150-ppm nitrogen with every irrigation or 200 to 300 ppm every other watering. Reduce the nutrients provided during the dormant periods (mid June through August and again in December through January) by providing 75 to 150 ppm with every other watering.

Maintain the media throughout the production cycle with a pH between 5.8 and 6.4. Interveinal chlorosis and stunted growth may occur as the result of iron deficiency caused by high pH levels (greater than 6.5). Applications of EDDHA iron (Sprint 138 ) can be applied to alleviate these symptoms. Ultimately, maintaining the pH within the recommended ranges is the best strategy for preventing or correcting iron deficiency symptoms.

‘Ballerina Ruffles’ prefers to be grown under average irrigation regimes. Never allow the plants to dry out to the point wilting occurs; wilting leads to root injury and increases their susceptibility to root rots. When irrigation is necessary, water them thoroughly and allow the medium to dry out slightly between waterings. Additionally, avoid over watering them during the hot summer months as crown rots often develop while wet conditions coincide with high heat and humidity.

Helleborus are shade perennials and do not tolerate high light levels when they are grown at greenhouses or nurseries. Therefore, they should be produced in facilities which have the ability to provide shade, particularly during the brightest, warmest months of the year. Maintain light levels below 6,000 foot-candles. I recommend producing helleborus under 50 to 75 percent shade cloth during the summer months.

Insects and Diseases

Compared to many perennials, the occurrence of insect pests and diseases on helleborus is minimal. The primary insect pests of helleborus are aphids and the most common diseases are Botrytis, powdery mildew, and crown/root rot. All of these pests and diseases can be detected with routine crop monitoring; control strategies may not be necessary unless the scouting activities indicate actions should be taken.

Temperature and Scheduling

Unfortunately, like other helleborus from seed, ‘Ballerina Ruffles’ has a long juvenile phase resulting in a longer amount of production time than most perennials. When possible, use large starting materials which usually are more mature than smaller sized liners. To produce plants which flower uniformly, it is best to transplant the plugs in late spring (May) the year before they are needed for sales. This extended production time is necessary to help the plants overcome juvenility, for bulking and to increase the number of flowers they will produce. Using smaller starting materials or not providing sufficient production time will lead to smaller plants with inconsistent or sporadic flowering.

Helleborus requires vernalization for flowering. The cold treatment should be delivered to plants that have been properly bulked up in the final container. There are often a certain percentage of plants which do not flower even after a long bulking period has been provided; after an additional growing season, these plants will flower after being vernalized the following year. After vernalization, they can be grown at natural day lengths.

In many instances, the plants will develop flowers during the late winter without any heat being provided. In many instances, growers find that helleborus flower before they need them. In these cases, it is necessary to keep them cold as long as possible by providing ventilation any time the outside temperatures are above 35° F. One of the benefits of double flowering helleborus like ‘Ballerina Ruffles’ is they have an extended bloom time with flowers lasting up to 12 weeks. If it is necessary to hasten flower development, provide a couple weeks of heat with 24 hour average temperatures of 55° F.

Availability

Currently, seed of helleborus ‘Ballerina Ruffles’ is not available to growers. Plugs can be obtained from a limited number of perennial propagators including GET Group (www.getgroupinc.com), North Creek Nursery (www.northcreeknurseries.com), Stonehouse Nursery (www.stonehousenursery.com) and Walters Gardens (www.waltersgardens.com).