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Extension > Yard and Garden News > Rose Classes and their Performance in Minnesota: Part 2

Rose Classes and their Performance in Minnesota: Part 2

Kathy Zuzek, UMN Extension Educator

Old Garden Roses

The earliest rose classes fall within a group of roses called the Old Garden Roses. These are the classes that were in existence before 1867 when the first Hybrid Tea was developed. The earliest classes in chronological order are the Gallicas, Damasks, Albas, Centifolias, and Mosses. These five classes were all in existence before 1800 and share some common traits. With few exceptions, they bloom only in spring on previous year's canes. In contrast to the Hybrid Teas, these roses are valued for their mature flowers rather than their buds. Buds are often round or globular and open to produce blooms that are cupped, domed, or are shallow saucers. Oftentimes small inner petals are enclosed within larger outer petals; sometimes petals are produced in a quartered arrangement. Colors among these 5 classes are restricted to pink, white, mauve, maroon, or purple.

Gallicas are the oldest class of Old Garden Roses and are known for their beautiful fragrance and blooms of rich colors like deep pink, violet, mauve, purple, or crimson. You can also find varieties with striped or mottled petals (Photo 1, below). Leaves are typically dark green, stiff, and a bit rugose or wrinkled. Plant habit is compact and upright and many Gallicas will sucker (Photo 2, below). At the Minnesota Landscape Arboretum (MLA), Gallica canes typically suffer some winter injury. They commonly die back to the snowline. If snow cover is absent, they often die back to the ground. When dieback to the ground occurs in Gallica cultivars or any other cultivar that blooms on previous years' wood, flowering does not occur the following spring bloom. 'Alika' is a very hardy Gallica and rarely suffers from winter injury at the MLA. Many Gallicas at the MLA show high levels of blackspot tolerance.

The first Damask rose was probably a hybrid created in nature from a Gallica rose and Rosa phoenicea, a species rose with small white flowers. Damask blooms are usually a clear pink or white and are known for their strong fragrance. Typical leaves are gray-green, downy on the underside, and composed of long leaflets. Damasks produce long arching canes but at the MLA, some winter injury is common among Damask cultivars so plant height is often reduced. Most cultivars have slight levels of blackspot infections. 'Cesonie' is a very blackspot-tolerant Damask cultivar (Photos 3&4, below).

Albas were created when a natural hybrid occurred between a Damask rose and Rosa canina, a European rose species often called the dog rose. Alba flowers are usually white, ivory, or light pink and leaves are gray-green or blue-green. Albas are typically taller and hardier than Gallicas, Damasks, Centifolias, and Mosses but some winter injury to canes still occurs at the MLA. 'Alba semi-plena' (Photos 5&6, below) has historically shown the best combination of winter hardiness and blackspot tolerance among Albas at the MLA.

Centifolias were developed by the Dutch in the 1600s from R. canina, R. gallica, R. moschata, and R.phoenicea. Flower buds are globular and open to display pink or white, fragrant, cupped blooms (Photos 7, below). Flowers have a high number of tightly packed petals that envelop each other like leaves of a cabbage, hence the common name "cabbage rose". Leaves are smoother and less wrinkled than Gallica foliage. Cabbage roses are taller like the Albas and the Damasks and their plant habit is often described as floppy or lanky (Photo 8, below). At the MLA, some winter injury is common can reduce plant height the following summer. Blackspot infections are more severe on Centifolias than on the Albas, Damasks, and Gallicas.

In the late 1600's a spontaneous mutation occurred on a Centifolia roses that resulted in the development of balsamic-scented glandular growths that look like moss on the stems and flowers of the rose. These mutated plants or sports were called the Moss Roses. The development of new moss rose varieties was a fad in the last half of the 19th century and cultivars were developed that ranged from small to large in plant habit with white, pink, and maroon blooms that had either soft or hard, prickly moss covering stems, flowers and occasionally leaves. Winter injury on Moss Roses is common at the MLA. 'Henri Martin' is a particularly blackspot-tolerant cultivar (Photo 9, below).

In the late 1700's R. chinensis, the China rose, and R. odorata, the tea rose, arrived in Europe from Asia. China roses have an open and airy plant habit, sparse foliage, and blooms that are shapeless compared to the Old Garden Roses. The tea rose is very similar to the China rose except that it is less hardy, has larger blooms that open from tall elegant buds, and flower scent is similar to fresh tea leaves. What excited gardeners and breeders was the ability of both the China rose and the tea rose to bloom repeatedly through the growing season. Soon repeat-flowering plants were created by combining the Gallicas, Damasks, Centifolias, and Mosses with the China rose and the Tea rose and four new rose classes developed. Portlands and Bourbons are both descended from the Damask and China roses. Portland Roses are known for their short stems and compact plant habit, dense foliage, and attractive purple, pink, or white flower forms. Bourbons are known for fragrant, rich-colored, many-petalled blooms that are produced on tall arching canes. In warmer climates bourbons are used as climbers and pillar roses. Hybrid Perpetuals resulted from crosses among many rose classes when rose exhibitions became popular. In this class, plants were selected for lovely flower buds and flowers. Plant habit was of little concern. As a result, hybrid perpetual plants are often described as clumsy and too large. Tea Roses, known for their tall, elegant buds, were created when R. odorata was crossed with the Bourbon roses and another rose class called the Noisettes. All four of these classes are more suited to growth in warmer climates and are not adequately hardy for Zone 4 winters.

Modern Roses

When Tea Roses were hybridized with the Hybrid Perpetuals, the Hybrid Tea class was created and the era of modern roses was started. Hybrid Teas with their tall elegant buds and beautiful flower form (Photos 10, below) dominated the rose world as a garden plant in the last half of the 20th century. They are not hardy in Minnesota and are typically very susceptible to blackspot.

The first Polyantha Rose was probably the result of an accidental cross of a China Rose and R. multiflora. Polyanthas are a class of small-statured roses who inherited their large clusters of small one-inch flowers and superior hardiness from their R. multiflora ancestor. 'The Fairy' (Photo 11, below) and its darker pink sport 'Lovely Fairy', are reliably crown-hardy and very blackspot-tolerant in the southern half of Minnesota and bloom freely all through the growing season. The Northern Accent Roses 'Ole', 'Sven', and 'Lena' are crown-hardy with rapid spring regrowth in Zones 3&4, have high blackspot-tolerance, and flower throughout the growing season.

When Polyantha Roses were combined with Hybrid Teas, Floribunda Roses were created. Floribundas produce blooms in clusters like their Polyantha parent but also have the more elegant bud and flower form and the decreased cold hardiness of their Hybrid Tea ancestors. Floribundas are typically not hardy in Minnesota. Two cultivars that are Zone 4-hardy and blackspot-tolerant are 'Nearly Wild' and 'Chuckles' (Photo 12, below). Both show high levels of blackspot tolerance.

Hybrid Rugosa cultivars are descended from R. rugosa with its rugose or wrinkled foliage and large colorful round hips. There are two types of Hybrid Rugosa cultivars. The first are plants that are 100% rugosa and typically show no winter injury, little blackspot incidence, produce mauve, white, or pink blooms through the growing season (Photo 13, below), and produce a beautiful crop of large round colorful hips in fall (Photo 14, below). These plants thrive even in the coldest parts of Minnesota as long as 1) soil pH is neutral or slightly acidic and 2) rose stem borer and mossy rose galls are removed and destroyed promptly. Examples in this group include 'Blanc Double de Coubert', 'David Thompson', 'Frau Dagmar Hartopp', and 'Jen's Munk'. The second group of Hybrid Rugosas have one R. rugosa parent , but the 2nd parent is a non-rugosa rose such as a Shrub Rose, a Hybrid Tea, a Floribunda, or a Miniature Rose. This group usually has less rugose foliage, few or no hips, more susceptibility to blackspot, a wider variety of flower color, and a dramatic loss of cane hardiness that prevents them from being grown in Zone 3 and oftentimes Zone 4.

Shrub Roses are a "catch all" category for roses with diverse genetic backgrounds that don't fit anywhere else. Common traits among this group include a "shrubby" plant habit compared to cultivars in other modern rose classes, increased winter hardiness, and improved disease resistance. Some are repeat-blooming. Others bloom only in spring. Minnesota gardeners can enjoy the shrub roses that resulted from Canadian breeding efforts in the 20th century and resulted in older cultivars like 'Therese Bugnet' or 'Lillian Gibson' and newer cultivars in the Explorer (Photo 15, below) and Parkland/Morden Series. Gardeners in the southern half of Minnesota can also take advantage of some of the repeat-blooming cultivars developed by Dr. Buck at Iowa State University during the last half of the 20th century such as 'Applejack', 'Country Dancer', 'Folksinger', 'Prairie Flower', 'Prairie Harvest', and 'Prairie Princess'. Newer Zone 4 additions to the shrub group that rebloom and show high blackspot tolerance include 'Candy Oh! Vivid Red', 'Carefree Delight', 'Carefree Spirit', 'Golden Eye', 'Pink Gnome', 'Polar Joy', and 'Snowdrift.'

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