The allure of blue roses has captivated gardeners and enthusiasts for centuries. These uniquely colored blooms add enchantment to any garden. Growing and caring for “blue” rose plants can be a rewarding experience, bringing exceptional visual appeal to outdoor spaces.
Understanding Blue Roses
True blue roses do not occur naturally because roses lack the specific gene for producing the blue pigment delphinidin. Despite extensive traditional breeding, roses have historically only yielded shades of red, pink, purple, and yellow. The quest for a genuine blue rose has relied on scientific innovation.
One common method for creating “blue” roses involves artificial dyeing, where white roses are placed in water infused with blue food-safe dye. The rose’s vascular system absorbs the colored water, distributing the pigment into the petals. This technique provides a cost-effective way to achieve blue-tinted flowers, though the color may appear less natural.
Genetic engineering represents a significant advancement. In 2004, Suntory, in collaboration with Florigene, developed the first genetically modified rose containing delphinidin. This involved inserting genes from pansy flowers into roses, allowing them to produce the blue pigment. The resulting ‘Suntory Blue Rose Applause’ rose exhibits a lavender or pale mauve color, rather than a pure blue, but it marked a substantial step towards achieving the color genetically.
Breeders have also developed rose cultivars through selective breeding that display bluish-lavender, purple, or slate-grey tones. These varieties, such as ‘Blue Moon’ or ‘Rhapsody in Blue’, are marketed as “blue” due to their cool color profiles, achieved by minimizing red and yellow pigments. While not genetically true blue, these selectively bred roses offer gardeners appealing bluish hues.
Growing “Blue” Rose Plants
Successful establishment of “blue” rose plants begins with careful site selection. Roses thrive in locations that receive at least six hours of direct sunlight daily. Adequate sunlight promotes vigorous growth and abundant blooms. Choosing a site protected from strong winds can also prevent damage.
Soil preparation is important for healthy rose growth. Roses prefer well-draining soil rich in organic matter, with a slightly acidic to neutral pH between 6.5 and 7.0. Incorporating several inches of compost or well-rotted manure into the planting area improves soil structure and nutrient content. For optimal root development, bone meal or superphosphate can be mixed into the soil removed from the planting hole.
When planting, dig a hole 15 to 18 inches deep and 18 to 24 inches wide, ensuring it accommodates the root ball. For grafted roses, the graft union should be positioned 1 to 2 inches below the soil surface. After placing the plant, backfill the hole with prepared soil, firming it to remove air pockets, and water thoroughly to settle the soil.
Proper spacing between rose plants is important for air circulation, which helps prevent fungal diseases like black spot and powdery mildew. Plant roses about 24 inches apart, or two-thirds of their expected mature height.
Caring for Your “Blue” Rose Plant
Consistent watering is important for healthy “blue” rose plants. Newly planted roses require frequent watering until established. Established roses benefit from deep, infrequent watering, such as once a week, providing enough water to penetrate the root zone. Water should be directed at the base of the plant to avoid wetting foliage, which can encourage fungal diseases.
Fertilization supports robust growth and prolific blooming. Begin fertilizing established roses in early spring when new growth appears. A balanced fertilizer formulated for roses can be scattered around the drip line of the bush. Repeat fertilization every three to four weeks during the growing season, or after each bloom cycle. Stop fertilizing six to eight weeks before the first anticipated frost to prevent tender new growth from being damaged by cold.
Pruning maintains the shape, health, and bloom production of rose plants. The best time to prune most roses is in late winter or early spring, as new growth begins. Remove any dead, diseased, or damaged canes, making clean cuts at a 45-degree angle about a quarter-inch above an outward-facing bud. This encourages outward growth and improves air circulation. Deadheading spent blooms throughout the summer also encourages more flowers.
Managing pests and diseases is part of rose care. Good air circulation, achieved through proper spacing and pruning, prevents common fungal issues. Regularly inspecting plants for signs of pests or diseases allows for early intervention. Removing fallen leaves and plant debris from around the base of the rose can also reduce disease transmission.
In colder climates, winter protection helps roses survive freezing temperatures. Mound soil, compost, or shredded leaves around the base of the plant. This mounding helps minimize damage from freeze-thaw cycles.
Popular “Blue” Rose Varieties
While true blue roses are rare, several cultivars offer captivating shades of lavender, mauve, and purplish-blue. ‘Blue Moon’ is a hybrid tea rose known for its strong fragrance and silvery-lavender blooms. Its elegant, high-centered flowers make it a favorite for cut arrangements.
‘Blue Girl’ is another hybrid tea that produces deep lavender-blue blossoms. This variety has a classic rose form and robust growth habit.
‘Rhapsody in Blue’ offers clusters of deep purple flowers that mature to a slate-blue shade, providing a continuous display. ‘Lavender Lassie’ is a shrub or climbing rose with fragrant, pale lavender-pink blooms that appear in large clusters.
The genetically engineered ‘Suntory Blue Rose Applause’ has a unique violet-blue hue, a result of delphinidin production. This variety represents a significant scientific achievement in the quest for blue roses.