Purple dahlias are cherished for their rich, regal blooms, adding elegance to gardens and floral displays across the USA. Part of the Asteraceae family, these herbaceous perennials offer shades from deep violet to soft lavender, complementing diverse color palettes. Their vibrant flowers bloom from mid-summer to the first frost, enhancing beds, borders, and arrangements.
Native to Mexico, purple dahlias were cultivated by the Aztecs before reaching Europe in the 16th century. By the 19th century, breeders developed numerous forms, boosting their global appeal. In the U.S., they became garden staples, thriving in various climates and celebrated for their striking hues and versatility.
Purple dahlias feature diverse flower forms, including single, double, cactus, and decorative types, with petals ranging from smooth to spiky. Plants grow 1-6 feet tall, with green foliage supporting sturdy stems. Their tuberous roots store energy, enabling regrowth annually, though tubers are lifted in colder U.S. zones (2-7).
Purple dahlias thrive in full sun with well-drained, fertile soil (pH 6.5-7.0) and consistent moisture. Planted in spring (April-May), they bloom July to October in the USA, available as tubers or cut flowers at nurseries and markets, especially in states like California and Oregon.
While not a food source, purple dahlias enrich gardens by attracting pollinators like bees. Their bold blooms provide emotional nourishment, enhancing well-being. Low-maintenance with proper care, they’re a sustainable choice for vibrant, health-conscious U.S. landscapes.
Purple Dahlias
Purple Gem
A semi-cactus dahlia with vibrant, deep purple blooms that create a striking, spiky starburst effect. Its elongated, tubular petals radiate drama, making it ideal for bold garden displays or cut flowers. This cultivar is known for its robust growth and long bloom season.
Identifying Characteristics:
- Deep purple, semi-cactus blooms, 6-8 inches across.
- Long, pointed, partially rolled petals with a spiky look.
- Plant height of 3-4 feet, spreading 18-24 inches.
- Blooms mid-summer to frost; strong, upright stems.
Thomas Edison
A formal decorative dahlia boasting large, fully double blooms in a rich, velvety purple hue. Its broad, smooth petals form a symmetrical, lush flowerhead, perfect for exhibitions, bouquets, or as a garden focal point, exuding classic elegance.
Identifying Characteristics:
- Velvety purple, formal decorative blooms, 8-10 inches across.
- Broad, flat petals in a tightly packed, symmetrical arrangement.
- Plant height of 4-5 feet, spreading 18-24 inches.
- Blooms mid to late summer; sturdy stems for cutting.
Blackberry Ripple
A waterlily dahlia with medium-sized blooms featuring a blend of soft purple and creamy white streaks. The layered, slightly cupped petals resemble a water lily, offering a delicate, painterly effect for garden beds or arrangements.
Identifying Characteristics:
- Soft purple with white streaks, waterlily blooms, 6-8 inches across.
- Layered, shallow, cupped petals with a soft texture.
- Plant height of 3-4 feet, spreading 18-24 inches.
- Blooms late summer to frost; open, delicate form.
Verrone’s Obsidian
A single-flowered dahlia with small, star-shaped blooms in a deep, almost black-purple hue. A single layer of rounded petals surrounds a golden disc, attracting pollinators and adding contrast to mixed borders or naturalistic gardens.
Identifying Characteristics:
- Deep black-purple, single blooms, 3-4 inches across.
- Rounded, flat petals in a single layer; golden central disc.
- Plant height of 2-3 feet, spreading 12-18 inches.
- Blooms mid-summer to fall; open, pollinator-friendly structure.
Midnight Moon
A collarette dahlia with medium blooms showcasing a single layer of soft lavender-purple petals and a ruffled, lighter purple inner collar. Its open, layered look adds charm to containers, borders, or as a cut flower.
Identifying Characteristics:
- Lavender-purple outer petals with a lighter purple collarette, 4-5 inches across.
- Single petal layer with ruffled inner florets; yellow disc.
- Plant height of 3-4 feet, spreading 18-24 inches.
- Blooms mid-summer to frost; collarette form with textured contrast.
Jescot Julie
An orchid-flowered dahlia with unique, medium-sized blooms in a vibrant purple shade. Petals curve backward, creating an exotic, star-like appearance that stands out in garden beds or as a focal point in arrangements.
Identifying Characteristics:
- Vibrant purple, orchid blooms, 4-6 inches across.
- Backward-curving, rolled petals in a star-shaped form.
- Plant height of 3-4 feet, spreading 18-24 inches.
- Blooms late summer to fall; exotic, open structure.
Purple Haze
A cactus dahlia with large, spiky blooms in a bold, magenta-purple hue. Its long, tubular petals twist and curl, creating a dynamic, fiery effect, perfect for adding drama to borders or large floral displays.
Identifying Characteristics:
- Magenta-purple, cactus blooms, 8-10 inches across.
- Long, rolled, twisting petals with pointed tips.
- Plant height of 4-5 feet, spreading 18-24 inches.
- Blooms mid to late summer; spiky, radiant form.
Arabian Night
A formal decorative dahlia with medium to large, fully double blooms in a deep, wine-purple shade. Its tightly packed petals form a rounded, lush flowerhead, ideal for cut flowers or creating a luxurious garden aesthetic.
Identifying Characteristics:
- Deep wine-purple, formal decorative blooms, 6-8 inches across.
- Broad, smooth petals in a dense, rounded arrangement.
- Plant height of 4-5 feet, spreading 18-24 inches.
- Blooms mid-summer to frost; elegant, symmetrical form.
Diva
A ball dahlia with perfectly spherical, medium-sized blooms in a rich, royal purple hue. The tightly packed petals create a pompon-like effect, making it a favorite for bouquets and compact garden spaces.
Identifying Characteristics:
- Royal purple, ball blooms, 4-6 inches across.
- Spherical, dense, uniform petal arrangement.
- Plant height of 3-4 feet, spreading 18-24 inches.
- Blooms mid to late summer; rounded, compact form.
Purple Flame
A semi-cactus dahlia with vibrant, violet-purple blooms that blend into lighter tips, creating a gradient effect. Its spiky, partially rolled petals add texture and energy, suitable for bold garden displays or arrangements.
Identifying Characteristics:
- Violet-purple blooms with lighter tips, 6-8 inches across.
- Partially rolled, pointed petals with a spiky look.
- Plant height of 4-5 feet, spreading 18-24 inches.
- Blooms late summer to frost; semi-cactus form with gradient color.
Lavender Perfection
A dinnerplate dahlia with massive, fully double blooms in a soft lavender-purple shade. Its broad, slightly curled petals form a grand, rounded flowerhead, ideal for exhibitions or as a garden centerpiece.
Identifying Characteristics:
- Soft lavender-purple, formal decorative blooms, 10-12 inches across.
- Broad, curled petals in a symmetrical, full arrangement.
- Plant height of 4-5 feet, spreading 18-24 inches.
- Blooms mid-summer to frost; large, sturdy stems.
Mystic Illusion
A single-flowered dahlia with small, dark purple blooms contrasted by dark, almost black foliage. A single layer of petals surrounds a yellow disc, creating a striking, modern look for containers or borders.
Identifying Characteristics:
- Dark purple, single blooms, 3-4 inches across.
- Single layer of rounded petals; yellow disc; dark foliage.
- Plant height of 2-3 feet, spreading 12-18 inches.
- Blooms mid-summer to fall; compact, contrasting leaves.
Voodoo
A cactus dahlia with large, deep magenta-purple blooms that exude intensity. Its long, rolled petals twist outward, creating a spiky, explosive effect, perfect for dramatic garden beds or cut flowers.
Identifying Characteristics:
- Deep magenta-purple, cactus blooms, 8-10 inches across.
- Long, tubular, twisting petals with pointed ends.
- Plant height of 4-5 feet, spreading 18-24 inches.
- Blooms late summer to frost; spiky, bold form.
Purple Taiheijo
A waterlily dahlia with medium-sized, soft purple blooms featuring layered, slightly cupped petals. Its delicate, open structure resembles a water lily, adding elegance to garden beds or floral arrangements.
Identifying Characteristics:
- Soft purple, waterlily blooms, 6-8 inches across.
- Layered, shallow, cupped petals with a gentle texture.
- Plant height of 3-4 feet, spreading 18-24 inches.
- Blooms mid to late summer; open, refined form.
Laciniated Purple
A laciniated dahlia with medium to large blooms in a vibrant, royal purple hue. Its fringed, split-tipped petals create a feathery, textured effect, adding intrigue to borders or as a statement in bouquets.
Identifying Characteristics:
- Royal purple, laciniated blooms, 6-8 inches across.
- Fringed, split-tipped petals with a feathery look.
- Plant height of 4-5 feet, spreading 18-24 inches.
- Blooms late summer to frost; intricate, textured form.
General Notes
- Bloom Season: Purple dahlias typically bloom from mid-summer (July) to the first frost (October-November), depending on U.S. region and climate (USDA zones 8-11 for overwintering, tubers lifted in zones 2-7).
- Growth Requirements: Prefer full sun, well-drained, fertile soil (pH 6.5-7.0), and regular watering. Stake taller varieties like Thomas Edison or Lavender Perfection to support heavy blooms.
- Uses: Ideal for garden borders, containers, cut flowers, and exhibitions due to diverse sizes (3-12 inches) and forms (e.g., decorative, cactus, single).