Roses are grown by millions of gardeners throughout the world for their beautiful flowers. To reduce the confusion of selecting between thousands of rose varieties, roses are classified in various groups. The broadest classification separates them into species and shrub roses; old garden roses; and modern roses.
Species roses are those roses found growing in the wild. Shrub roses are closely related to the species rose but have been bred to make them more suitable for a garden setting. Species roses grow on their own roots and many are hardy for our growing area without requiring winter protection. Species and shrub roses to consider include Rosa blanda, Rosa eglanteria, Rosa foetida, and Rosa rugosa.
Old garden roses or simply old roses are those varieties created before 1867. Why the year 1867? This year was established by the American Rose Society to commemorate the introduction of the first hybrid tea rose. All roses introduced after 1867 are considered to be modern roses. Old roses are very fragrant and offer a wide variety of growth habits. Rosa gallica grows just 3 to 4 feet forming a nice compact bush. Rosa alba varieties may grow 6 to 9 feet in height.
Modern roses are the most common type of rose found at the garden center or nursery. Most are grafted onto a hardy root stock and must be protected from winter injury. There are five main groups of modern roses: hybrid teas, polyanthas, floribundas, grandifloras, and miniatures. The hybrid tea is the most popular rose grown. Flowers are produced singly on long stems from early summer until frost. The polyantha rose is a cross between Rosa multiflora and the hybrid tea. Polyanthas perform well in massed plantings because of their low growth (2 feet). The floribunda rose is a cross between the hybrid tea and the polyantha. They grow 2 to 3 feet tall and produce continuous clusters of flowers on medium length stems. The grandiflora is a cross between the hybrid tea and the floribunda with the best qualities of both. The flowers (usually double) are produced singly or in small clusters. The 3 to 6 foot tall plants are useful in a background setting. The miniature rose grows just 6 to 18 inches tall with blossoms ranging from 1/2 to 1 1/2 inches wide. The miniatures are useful for edging and containers, both indoors and out. The plants are quite hardy, but still require winter protection throughout Iowa.
Roses are graded as 1, 1 1/2, and 2 based on size and number of canes. For the best quality rose, purchase a number 1 grade. To meet this standard, the bush is required to have at least 2 canes 18 inches in length for hybrid teas and grandifloras or 2 canes 15 inches in length for floribundas. Branching must begin no more than 3 inches above the bud union. Polyanthas require 4 canes, 12 inches or longer to meet the requirements of a number 1 grade.
Roses are often sold as dormant, bare root plants. Before purchasing, examine the plant carefully. Avoid those with deformed growth, abnormal swellings, and discolored canes which may indicate disease. The canes should be firm, plump, and green. The plant should be well shaped and the root system should be well branched. Bare root roses can be planted as soon as the ground has thawed and the danger of severe frosts has passed. Prior to planting, soak the root system in water for a few hours (no more than 24 hours). Trim any damaged or broken roots before planting. If you are unable to plant the rose directly after purchase, it is important to keep the plant in a cool, moist location to prevent growth and dessication. Sawdust, peatmoss, or perlite are excellent moisture-retaining materials. Plant as soon as time allows.
Roses are also available as container-grown plants. Select those that have vigorous, healthy growth. Avoid those that have die back or thin twiggy growth. Containerized roses can be planted throughout the spring and summer as long as water is sufficient.
Good quality is important in the selection of any garden plant and roses are no exception. By selecting roses suitable for your planting situation and the best quality, successful rose gardening becomes much easier.
This article originally appeared in the March 31, 1993 issue, pp. , 1993 issue, pp. 32-33.