The Florist's Guide to Large Dahlia Varieties
Large dahlias are among the most spectacular flowers available to florists, offering dramatic focal points and stunning visual impact in arrangements. These impressive blooms, typically measuring 8-12+ inches across, can transform any floral design from ordinary to extraordinary.
Understanding Dahlia Size Classifications
Dahlias are classified by bloom size, with the largest categories being:
Giant/AA: 10+ inches in diameter
Large/A: 8-10 inches in diameter
Medium/B: 6-8 inches in diameter
For maximum impact, florists should focus on Giant and Large varieties, though some Medium varieties can also provide substantial presence in arrangements.
Top Giant Dahlia Varieties (10+ inches)
Café au Lait Perhaps the most famous giant dahlia, Café au Lait produces enormous creamy-white blooms with subtle peachy-pink edges. The flowers can reach 12-14 inches across and feature a classic dinner-plate form with broad, slightly cupped petals. This variety is exceptionally popular for wedding work due to its neutral coloring and impressive size.
Thomas Edison This deep purple giant creates dramatic, almost black-purple blooms that can exceed 10 inches. The rich color provides excellent contrast in arrangements and photographs beautifully. The sturdy stems make it reliable for large arrangements.
Labyrinth A stunning coral-orange giant with exceptional form and size consistency. The blooms often reach 12+ inches and maintain their shape well in arrangements. The vibrant color works beautifully in autumn designs.
American Dawn Features massive pink blooms with white tips on each petal, creating a stunning two-tone effect. The flowers regularly reach 10-12 inches and have excellent keeping quality when properly conditioned.
Premier Large Dahlia Varieties (8-10 inches)
Café au Lait Royal A deeper-colored cousin to Café au Lait, producing burgundy-bronze blooms with the same impressive size and form. Excellent for creating rich, sophisticated arrangements.
Otto's Thrill Brilliant orange-red blooms with exceptional substance and longevity. The 8-10 inch flowers have sturdy petals that hold up well in arrangements and shipping.
Nadia Ruth Soft lavender-pink blooms with excellent form and size consistency. This variety produces numerous large blooms per plant and has become increasingly popular for special events.
Bishop of Auckland Deep red blooms with dark foliage create striking contrast. While slightly smaller than true giants, the 8-9 inch blooms have exceptional keeping quality.
Growing Considerations for Florists
Soil and Planting Large dahlias require rich, well-draining soil with consistent moisture. Plant tubers after soil temperature reaches 60°F, spacing them 3-4 feet apart to accommodate their substantial size. These varieties typically need 4-5 months from planting to peak bloom production.
Support Systems Giant dahlias require sturdy staking due to their substantial flower heads. Install stakes at planting time to avoid damaging tubers later. Use soft ties to secure stems as they grow, typically requiring support when plants reach 2-3 feet in height.
Fertilization Heavy feeders that benefit from regular fertilization throughout the growing season. Use a balanced fertilizer early in the season, then switch to a lower-nitrogen formula once buds begin forming to encourage flower production over foliage.
Harvesting and Conditioning
Optimal Harvest Time Cut large dahlias when blooms are about 75% open, typically in early morning when stems are fully hydrated. Look for petals that are firm and just beginning to separate from the center.
Conditioning Protocol Immediately place cut stems in cool water and recut underwater at an angle. Large dahlias benefit from warm water conditioning (100-110°F) for the first hour, then transfer to cool water. Strip lower foliage and place in floral preservative solution.
Longevity Tips Properly conditioned large dahlias can last 5-7 days in arrangements. Change water every 2-3 days and recut stems. Keep arrangements away from direct sunlight and heat sources to maximize vase life.
Design Applications
Focal Point Usage Large dahlias work best as primary focal points in arrangements rather than filler flowers. Their substantial size means one or two blooms can anchor an entire design. Consider their visual weight when balancing arrangements.
Complementary Flowers Pair large dahlias with smaller, more delicate flowers to create contrast and balance. Excellent companions include spray roses, lisianthus, eucalyptus, and delicate grasses. Avoid competing with other large focal flowers.
Color Coordination The wide range of available colors allows large dahlias to work in virtually any color scheme. Consider the undertones when selecting varieties – some "white" varieties have pink or yellow undertones that may clash with pure white flowers.
Seasonal Availability and Storage
Large dahlias are typically available from mid-summer through the first hard frost, making them excellent choices for late summer and fall arrangements. In most climates, peak availability occurs from August through October.
For storage, keep cut stems in cool conditions (35-40°F) and high humidity. Properly stored blooms can maintain quality for several days before use, though they're best used as soon as possible after cutting.
Special Considerations
Large dahlias can be top-heavy and may require additional support in tall arrangements. Their substantial water needs mean arrangements will require frequent monitoring and water replenishment. The impressive size and relatively short availability window often command premium pricing, making them ideal for special occasion work where their dramatic impact justifies the cost.
These magnificent varieties offer florists the opportunity to create truly spectacular arrangements that leave lasting impressions on clients and event attendees.
