How to Grow White Double
iNaturalist
White Double
Dahlia × hybridus 'White Double'
flowerWhite Double is a stunning dahlia cultivar featuring fully double white blooms with multiple layers of petals forming a formal, symmetrical flower shape. These elegant flowers make excellent cut flowers and garden focal points, blooming prolifically throughout the growing season. The plant grows as a tender perennial typically treated as an annual in most climates.
When should you plant White Double in your zone?
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Example White Double timeline · Pittsburgh, PA (Zone 6b)
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Plant White Double
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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First White Double blooms
Around Jun 16≈ 60 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact White Double dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Zones 8-11; grow as annuals or lift tubers in zones 3-7
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Tuber/Transplant Establishment
2-3 weeksRecently planted tubers or transplants begin developing root systems and initial leaf shoots emerge from the soil.
Keep soil warm (60°F+) and consistently moist. Plant after last frost date. Provide staking support early to prevent wind damage.
Vegetative Growth
3-4 weeksPlant develops multiple stems and bushy foliage with increasingly larger leaves; no flowers yet but rapid height and width growth.
Pinch center stem when plant reaches 12 inches tall to encourage branching and bushier growth. Water regularly and apply balanced fertilizer every 2-3 weeks.
Bud Formation
2-3 weeksFlower buds begin to form at stem tips and axils; plant structure is mostly established.
Switch to lower nitrogen, higher phosphorus fertilizer (e.g., 5-10-10) to promote flowering. Continue staking and support. Remove side buds for larger blooms if desired.
Flowering
8-12 weeks or until frostLarge, fully double white blooms open continuously in succession; peak ornamental period with prolific flowering.
Deadhead spent flowers regularly to encourage continuous blooming. Water deeply and consistently. Stake tall varieties. Apply mulch to retain moisture and regulate soil temperature.
Senescence/Dormancy Preparation
4-6 weeks or until frostAs temperatures cool in fall, flowering slows; tubers underground begin thickening and storing energy; foliage yellows.
Reduce watering as growth slows. In zones 8-9, allow plants to die back naturally and lift tubers after first frost. In colder zones, lift tubers before first frost for winter storage at 40-50°F.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Spray with water to dislodge; use neem oil or insecticidal soap; maintain adequate humidity
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Remove infested flowers; use sticky blue traps; apply spinosad or neem oil
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Hand-pick in early morning; use pheromone traps away from plants; apply neem oil
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Improve air circulation; spray with sulfur or potassium bicarbonate; remove infected leaves
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Remove affected flowers; improve drainage and air circulation; avoid overhead watering
Uses
Edible flowers
CulinaryDahlia petals are edible with a slightly sweet, earthy flavor and can garnish salads, desserts, and specialty dishes. They add elegant visual appeal to culinary presentations. [source]
Cut flower arrangements
CraftWhite Double dahlias are premier cut flowers prized by florists for their large, formal double blooms and long vase life (7-10 days). They serve as elegant focal flowers in wedding bouquets and high-end arrangements. [source]
Garden display and focal point
HouseholdThese striking white blooms create dramatic visual impact in garden borders, raised beds, and containers. They provide continuous color from summer through early fall. [source]
Pollinator support
WildlifeWhile fully double flowers have reduced nectar and pollen compared to single varieties, they still attract bees, butterflies, and other beneficial insects to the garden. [source]
Traditional herbal use
MedicinalIn traditional medicine, dahlia tubers have been used in some cultures for their potential anti-inflammatory and nutritive properties, though scientific evidence is limited. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Cut flowers in early morning when stems are fully hydrated, using sharp scissors or pruners. Cut at a 45-degree angle. Remove lower leaves from stems. Place immediately in cool water with floral preservative. Deadhead spent blooms throughout the season to maintain continuous flowering. For maximum bloom size, remove secondary flower buds leaving only terminal buds.
Fun Facts
- 🌱 Dahlias originated in Mexico where they were cultivated by the Aztecs, who valued the tubers as a food source. The plant is the national flower of Mexico.
- 🌱 A single White Double dahlia can produce 50+ blooms per season if deadheaded regularly, making it an exceptionally prolific flower.
- 🌱 Dahlia tubers can be divided like potatoes—each piece with an 'eye' (dormant bud) will grow into a new plant, allowing gardeners to propagate their own stock for free.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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