The search for a truly “blue” rose has captivated plant breeders for centuries, resulting instead in a stunning collection of cultivars that display shades of purple, lavender, and mauve. These unique colors bring an air of mystery and sophistication to any garden or floral arrangement. While the term “blue rose” is frequently used in commerce, it is fundamentally a misnomer for flowers that genetically cannot produce a pure blue pigment. The distinct hues of these prized plants make them stand apart from the traditional red, pink, and yellow varieties.
The Most Popular Purple Rose Varieties
The names given to these cultivars reflect the spectrum of colors, ranging from smoky slate to deep plum. One of the darkest and most popular is ‘Ebb Tide,’ a Floribunda rose known for its heavily petaled, deep plum-purple blooms that often have a smoky haze. This variety is highly sought after for its striking color and its exceptionally strong, spicy fragrance, often described as a mix of clove and citrus.
For those seeking a lighter, more classic lavender, the Hybrid Tea variety ‘Blue Moon’ is a benchmark cultivar. Its elegant, solitary blooms open slowly to a silvery-lavender color and carry a strong, refined perfume, making it a favorite for cut flowers. Closely related in color is ‘Cool Water,’ a dark lavender Hybrid Tea, and ‘Ocean Song,’ which presents a delicate, pale lavender hue.
A cultivar that pushes the boundaries of the color spectrum is the Shrub rose ‘Rhapsody in Blue,’ frequently cited as one of the closest to a true blue shade. Its semi-double flowers open in clusters with a violet-purple color, maturing to a distinctive slate-gray or mauve. Another well-regarded Floribunda is ‘Plum Perfect,’ which showcases plush, double flowers in a consistent violet-plum shade. The subtle differences in these cultivar names help gardeners distinguish between the deep violets, silvery lilacs, and smoky mauves available.
Understanding the Color Spectrum
The reason these roses are called purple, lavender, or mauve rather than blue lies in their genetic makeup and pigment composition. Rose color is determined by anthocyanins, which are water-soluble pigments found in the plant’s cell vacuoles. The specific hue depends on the type of anthocyanin present and the acidity, or pH, of the cell sap.
Traditional roses lack the gene for the enzyme flavonoid 3′,5′-hydroxylase (F3’5’H), necessary to produce the anthocyanidin called delphinidin. Delphinidin is the pigment responsible for generating the true blue and violet colors seen in flowers like delphiniums and petunias. Without the F3’5’H enzyme, roses synthesize pigments based on cyanidin, which results in red and pink hues.
Breeders achieve purple and lavender shades by manipulating the existing pigments through several factors. The color shifts toward the blue end of the spectrum when the vacuolar pH is more neutral or slightly alkaline, rather than the acidic conditions that favor red. The presence of co-pigments, such as flavones, can also interact with the anthocyanins, causing a bluer or darker appearance. These breeding efforts push the color boundary, but the underlying genetic limitation prevents the creation of a naturally occurring, pure blue rose.
Classification and Growth Habits
Purple-flowered roses are categorized into the same major horticultural classes as all other modern roses, which defines their size, form, and use in the garden. The two most common classifications for these varieties are Hybrid Tea and Floribunda. Hybrid Tea roses, such as ‘Blue Moon’ and ‘Cool Water,’ are characterized by their large, high-centered, solitary flowers on long, upright stems. This growth habit makes them the traditional choice for cutting and use in formal arrangements.
Floribunda roses, including ‘Ebb Tide’ and ‘Plum Perfect,’ are known for producing flowers in large clusters, often with a continuous blooming cycle. These plants tend to be bushier and more compact than Hybrid Teas, making them well-suited for mass plantings and mixed garden borders. Shrub roses, like ‘Rhapsody in Blue,’ represent a broader category with a rugged, vigorous growth habit and excellent disease resistance. The classification dictates the plant’s ultimate size, from a compact Floribunda to a taller, more upright Hybrid Tea.