Dahlias, with their striking appearance and diverse forms, are popular garden perennials. Their beauty comes from intricate petal arrangements and a remarkable spectrum of colors, ranging from compact varieties to towering specimens.
The Spectrum of Dahlia Colors
Dahlias exhibit an extensive palette of colors, encompassing almost every shade imaginable. Reds range from bright cherry to deep crimson, while oranges span from soft peach to vibrant tangerine. Yellows can be found in delicate buttercream hues to saturated lemon and rich gold. Pinks vary from light blush to deep rose, and purples include lavender, lilac, and dark jewel tones. White dahlias appear in pure white, creamy tones, and even gray-white.
Despite this broad spectrum, true blue and black dahlias do not naturally occur. What appears as “blue” is typically a deep violet or lavender, as dahlias lack the specific gene to produce blue pigment. Similarly, “black” dahlias are very deep shades of burgundy, maroon, or dark purple, appearing black in certain lighting. These intensely pigmented varieties, like ‘Karma Choc’ or ‘Black Beauty’, achieve their dark appearance from high concentrations of anthocyanin pigments.
Why Dahlias Boast Such Color Diversity
The remarkable color diversity in dahlias results largely from centuries of human hybridization and selective breeding. Early dahlias were more basic in appearance, often single-flowered with open centers. Breeders selected plants with desirable traits, like increased petal count and varied colors, then cross-pollinated them to combine characteristics.
Dahlias have a complex genetic makeup, significantly contributing to their variability. Unlike many organisms that have two sets of chromosomes, most dahlias are octoploids, meaning they have eight sets of chromosomes. This genetic complexity allows for many potential combinations, leading to the wide range of colors, shapes, and sizes seen today. Dahlias also contain “jumping genes” (transposons) that move within the plant’s DNA, causing spontaneous mutations. This adds to their diversity and can lead to unexpected color changes.
Beyond Solid Hues: Patterns and Combinations
Beyond solid colors, dahlia blooms frequently display intricate patterns and combinations, adding visual interest. Bi-color dahlias feature two distinct, sharply separated colors on their petals, creating striking contrasts. Blended dahlias show colors that seamlessly fade, often presenting a soft transition of shades like peach, pink, and red hues evoking a sunset.
Other common patterns include stripes, where one color appears as lines or streaks on a base color, and picotee edges, where the petal margins are outlined in a contrasting shade. Variegated dahlias exhibit two or more distinct, contrasting colors on the petal face, appearing as flecks, dots, or splashes. These complex color expressions attest to the ongoing work of breeders and the dahlia’s inherent genetic fluidity.