The Crape Myrtle (Lagerstroemia) is a popular flowering shrub and small tree, highly valued for its extended summer bloom period and vibrant color palette. These plants are a common sight in warmer climates, offering colors that span from pure white and soft pinks to intense reds and deep purples. Many gardeners seek the darkest possible purple bloom for dramatic contrast in their landscape. Identifying the specific cultivars that achieve the most saturated, almost black-purple shade requires focusing on varieties known for their exceptional pigment density.
Defining the Darkest Purple Spectrum
The color spectrum of purple in Crape Myrtles presents a unique challenge because the deepest shades are typically not a pure, true purple. The color is derived from anthocyanin pigments, which often cause the flowers to lean toward the violet or magenta end of the spectrum. For this reason, the darkest varieties are frequently described using terms like “royal purple,” “deep violet,” or “black-violet” to convey their intensity.
Horticultural breeding focuses on maximizing pigment concentration to achieve saturation that appears nearly black from a distance. The industry uses names like ‘Midnight’ or ‘Black Diamond’ to categorize these intensely colored varieties, even though the flower remains a very dark purple. It is important to differentiate these deep purple varieties from cultivars that feature dark red or maroon flowers, as the color families remain distinct.
Leading Cultivars for Deep Purple Color
Determining the single “darkest purple” cultivar is difficult, as it often depends on the plant’s specific growing conditions. ‘Twilight’ is a long-standing contender for the deepest hue in the tree-form category. This cultivar, which can mature into a small tree reaching 20 to 35 feet, produces large clusters of rich, saturated purple flowers.
The more recent ‘Black Diamond Purely Purple’ is a strong competitor, noted for its striking combination of flower color and foliage. While the flowers are an intense, rich purple, the plant’s new growth and mature leaves maintain a dark burgundy or near-black color throughout the season. This dark foliage provides a high-contrast backdrop that visually amplifies the depth of the purple blooms.
Other popular contenders include ‘Catawba,’ a well-established variety known for its dense clusters of dark violet-purple flowers, typically maturing into a medium-sized tree. The cultivar ‘Blue Amethyst™’ has been marketed as the “deepest true purple ever bred,” highlighting the ongoing effort by breeders to achieve maximum color saturation. ‘Purple Velvet’ features very deep, black-violet tones, particularly in the dwarf and smaller shrub forms.
Environmental Factors Affecting Hue Intensity
While the potential for a dark purple flower is determined by the plant’s genetics, environmental factors significantly influence how intensely the color is expressed. The most important factor for achieving the deepest purple is providing the plant with ample direct sunlight. Crape Myrtles require a minimum of six to eight hours of full sun daily to develop the most vivid and saturated colors.
Planting a dark purple cultivar in partial shade often results in a lighter, softer, or more faded purple hue, reducing the desired intensity. Temperature also plays a role in pigment production; seasonal shifts and cooler overnight temperatures can sometimes lead to a slightly darker color expression. Color variation observed on a single plant is usually a result of the age of the individual blooms and the amount of direct sun they received during their formation.
Unlike plants such as hydrangeas, the flower color of Crape Myrtles is not sensitive to changes in soil pH. The concentration of the anthocyanin pigments dictates the darkness of the purple, and this is primarily a genetic trait. To ensure the darkest possible color, gardeners must focus on a location that receives maximum sunlight exposure throughout the growing season.