Most plants display green foliage due to chlorophyll pigments that maximize light absorption for photosynthesis. However, plants with deep purple, burgundy, or nearly black leaves offer a striking contrast, adding visual depth to any garden or interior space. This dramatic coloration is a natural feature, not a sign of distress, and understanding the science and specific varieties available helps growers select and maintain these unique specimens.
The Mechanism of Purple Pigmentation
The purple coloration in leaves is caused by anthocyanins, a group of water-soluble flavonoid pigments responsible for red, blue, and violet shades. These pigments are manufactured within plant cells and stored in the vacuoles, the fluid-filled sacs inside the cell. Anthocyanins do not mean chlorophyll is absent; rather, the purple pigment is concentrated enough to visibly mask the underlying green color.
Anthocyanins also serve a functional role as a protective barrier within the plant tissue. They work by absorbing excess photons and ultraviolet (UV) radiation that could otherwise damage the photosynthetic machinery. Production of anthocyanins is often triggered by environmental stress, such as intense light or cold temperatures, to protect the cells.
Popular Purple Plants for Indoor Settings
For indoor cultivation, several species are prized for their reliably vibrant purple foliage. These varieties generally require bright, indirect light to ensure their purple coloration remains intense; insufficient light exposure will often cause the plant to revert to a duller, greener shade.
The Purple Heart, scientifically known as Tradescantia pallida, is characterized by sprawling stems and leaves saturated with a deep, uniform purple color. This hardy perennial is often grown indoors in hanging baskets where its trailing habit is best displayed.
Another popular choice is the Purple Oxalis (Oxalis triangularis), often called the False Shamrock due to its distinctive three-lobed leaves. Its foliage displays a velvety purple-maroon hue and exhibits nyctinasty, folding its leaves closed at night or during low light conditions. The Purple Passion Plant (Gynura aurantiaca) offers a unique textural element with dark green leaves densely covered in fine, bright purple hairs, giving the plant a soft, fuzzy, iridescent appearance.
The Burgundy Rubber Plant (Ficus elastica ‘Burgundy’) provides a subtle yet sophisticated purple element, particularly in larger specimens. Its stiff, oblong leaves are deep green to near-black on top, but the undersides and new growth often feature a rich, burgundy-purple coloration.
Popular Purple Plants for Outdoor Settings
Outdoor gardening offers a vast array of purple-leaved specimens, ranging from groundcovers to large shrubs.
Shrubs
Among the most dramatic shrubs are the Ninebark (Physocarpus opulifolius) and Smokebush (Cotinus coggygria), both featuring cultivars developed specifically for dark foliage. Ninebark varieties like ‘Summer Wine Black’ grow as dense shrubs with deep burgundy-purple leaves that provide year-round interest in the landscape. Smokebush cultivars such as ‘Winecraft Black’ are known for their rounded, near-black foliage that retains its deep color throughout the summer before transitioning to fiery orange-red tones in the fall.
Perennials
For perennial borders, the Heuchera, commonly called Coral Bells, is a staple, with cultivars like ‘Wild Rose’ displaying a vivid rosy-purple foliage that resists fading even in high heat. Similarly, the Elderberry (Sambucus) cultivar ‘Black Lace’ provides an elegant, dark element with finely cut, almost fern-like leaves that appear nearly black, setting off its light pink flowers in early summer.
Annuals and Groundcovers
Annual plants and groundcovers also contribute significantly to the purple palette, often used in containers or as seasonal bedding. Ornamental sweet potato vine (Ipomoea batatas) is frequently planted for its trailing habit and heart-shaped leaves in shades of deep purple or black, offering quick coverage throughout the warm season. Coleus (Plectranthus scutellarioides) presents hundreds of varieties with leaf patterns that include striking combinations of purple, burgundy, and black, such as the ‘Black Prince’ cultivar.
Cultivating and Maintaining Rich Color
The intensity of purple foliage is primarily influenced by light, as anthocyanin production is directly related to the plant’s need for solar protection. Providing high light levels is the most effective way to ensure the coloration remains saturated and vibrant. The presence of blue and ultraviolet (UV) light wavelengths specifically promotes the biosynthesis of anthocyanins.
Environmental stressors, including cooler temperatures, can also trigger the plant to produce more anthocyanins. However, over-fertilizing with nitrogen may encourage the plant to prioritize chlorophyll production, potentially resulting in a dilution of the purple pigment and a greener appearance.