How Often Do Roses Bloom?

Many shrub roses bloom all summer long.

Roses fill the June garden with elegant blooms and soft fragrance, but they are perennials whose bloom is limited. Rosarians, botanists, plant geneticists and hobbyists have studied the plant for centuries. Through interbreeding species roses and hybridizing the resulting varieties, they have created plants that re-bloom or bloom almost continuously until the last rose of summer.

Deadheading

All flowering plants propagate by attracting insects, birds or animals that carry pollen from one bloom to another, fertilizing a seed in the bloom's ovary. Deadheading is the practice of removing blooms before seeds are fertilized. The practice fools the plant into producing more flowers in the hope of attracting more pollinators. Judy Lowe writes in the Christian Science Monitor that deadheading plants as they finish bloom, light fertilizer feeding and generous watering will keep roses blooming all summer long. Cuts to leaf clusters of five or seven stimulate new growth. All roses perform best in full sun.

Single Bloomers

Species roses from which all garden roses descend bloom once, in June. Many old garden roses -- rose hybrid varieties grown before the middle of the 19th century -- bloom only once in June. The first modern rose, the hybrid tea, bloomed in June. The tea rose, one of the antecedents of the hybrid tea, had blooms so large that their small stems could not support them. Grandiflora, a descendant of the hybrid tea, blooms once on shrubs that can grow tall enough to serve as hedges. Older shrub rose varieties bloom only in June. Old rambler roses such as Boursault also bloom once.

Re-Bloomers

Old garden damask, Bourbon, hybrid China and hybrid perpetual roses are repeat-blooming roses. Newer hybrid tea cultivars bloom in spring and, given proper cultural care, repeat every six weeks during all but the hottest summer weather. The pattern of many re-blooming roses, like that of ever-blooming climbing roses, repeats intermittently throughout the summer with a final flush after the weather turns cooler. Cleaning the shrubs after bloom, water and fertilizer prompts more luxuriant re-bloom.

Continuous Bloomers

Continuous blooming roses, unlike repeat bloomers, do not require a rest period between bloom periods. Roses are complex inflorescences and plants with large, intricate blooms, such as hybrid teas and damask roses, require large amounts of nutrients and time to recover after blooming. Continuous blooming inflorescences are either smaller or less complex than their flashier relatives. Some are self-cleaning but most require deadheading to keep blooming without interruption. Rugosa roses bloom continuously and are also remarkably disease-free and insect-resistant. Floribundas and polyanthas produce clusters of flowers in a spring blush that begins continuing production. Among the modern shrub roses that bloom throughout the summer are the Parkland Morden series, the Explorer series, Meidiland and Knockout roses.

References

• Christian Science Monitor; Your Roses Can Bloom Continually All Summer; Judy Lowe; 2008
• University of California Davis; Proper Flower Cutting Keeps Rose Bushes Blooming; Ed Perry; 1999
• University of Missouri Extension; Roses: Selecting and Planting; Chris Starbuck, Mary Kroening; 2004
• Rose Works; Types of Roses
• Santa Clarita Valley Rose Society: Types of Roses