FlowerDelphinium
Pacific Giant Series Delphinium
Pacific Giant Series delphinium brings the drama of a classic English cottage garden to zones 3-7, with towering spikes that reach 48-60 inches tall and burst with nearly fully double blooms in vivid colors. These perennials mature in their second year, rewarding patient gardeners with hardy, long-lasting flowers that rival fresh-cut larkspur or snapdragon in the vase. Thriving in full sun with straightforward care, they're a bold choice for reinvigorating tired flowerbed edges and garden walkways with dazzling color and architectural presence.
Photo © True Leaf Market
Growing Conditions
USDA Zone
3-7
Sunlight
Full Sun
Growth Stats
60 in
Height
TypeUpright
Spacing
36
Plant Profile
Sunlight
Full Sun
Water
—
Zones
3-7
Size
60in H x ?in W
Growth
—
Care
High
Hover over chart points for details
Highlights
These delphiniums command attention with their sheer height and densely packed flower spikes that seem almost impossibly full. The nearly complete doubling of the blooms creates an almost cloud-like texture along the stem, quite unlike the simpler, single-flowered varieties. They perform reliably across cold hardiness zones 3-7, so gardeners in harsh climates can grow something that feels genuinely special rather than settling for compromise plants.
Common Uses
Pacific Giant delphiniums are grown primarily as ornamental cut flowers and as architectural elements in perennial borders. The tall, columnar spikes with their fully double flowers make them exceptional substitutes for traditional larkspur or snapdragon in fresh bouquets, where they hold up remarkably well and add instant drama to any arrangement. Gardeners use them to create strong vertical lines in borders, to frame entryways and pathways, and to add height and structure to mixed plantings.
Growing Timeline
No timeline data available yet for this variety.
Care Instructions
Start Indoors
Start Pacific Giant delphinium seeds indoors 8-10 weeks before your last spring frost. Sow seeds on the surface of moist seed-starting mix or press them lightly into the soil, as they benefit from light exposure to germinate. Maintain temperatures around 70°F and keep the soil consistently moist but not waterlogged. Seedlings typically emerge within 15-20 days.
Transplant Outdoors
Harden off seedlings over 7-10 days by gradually exposing them to outdoor conditions. Transplant into the garden after the last frost date once soil has warmed. Space plants 36 inches apart in full sun, with 60 inches between rows if planting in a cutting garden format. Plant at the same depth they were growing in their cells.
Direct Sow
Direct sow seeds in fall, about 4-6 weeks before the first frost, for germination in spring. Alternatively, direct sow in early spring as soon as soil is workable, pressing seeds lightly into moist soil.
Harvesting
Cut Pacific Giant delphinium flowers for arrangements when the spike is about three-quarters open, with the lower and middle flowers fully open and the top buds still slightly closed. Cut stems in the early morning when they're most hydrated, using sharp shears to make a clean cut at least one-third of the way down the stem. Remove the lower leaves that would sit below the waterline in a vase. The flowers continue to open in the vase over several days, giving you an extended display.
Pruning
Deadhead spent flower spikes by cutting them just above the nearest set of healthy leaves to encourage additional bloom production and extend the flowering season. After the first heavy frost or when flowering ceases in fall, cut the entire plant back to ground level to prepare it for winter dormancy. In early spring, remove any winter-damaged growth once new shoots emerge.
Growing Calendar
Enter your ZIP code to see a personalized growing calendar for this plant.
Companion Planting
Pests & Diseases
Scientific Classification
Delphinium cultorum
Growth Habit
Upright
History & Origin
“The Pacific Giant Series represents a pivotal moment in delphinium breeding when hybridizers focused on creating perennial varieties with superior size, flower fullness, and reliability compared to their wild ancestors. Delphinium cultorum hybrids emerged from generations of selection for garden performance, combining the hardiness of perennial delphiniums with the showy, densely packed flower forms that make them garden showstoppers. This series specifically targets gardeners seeking dramatic cut flowers and garden presence without sacrificing the cold hardiness needed in northern climates.”