Hybrid

Delphiniums Pacific Giant Series

Delphinium elatum 'Pacific Giant'

These towering cottage garden classics produce magnificent spikes of densely packed flowers in shades of blue, purple, pink, and white, reaching impressive heights that create stunning vertical drama. The Pacific Giant series is renowned for producing the tallest and most robust delphiniums, with flower spikes that can extend 3-4 feet in length. Though challenging to grow, their spectacular display rewards dedicated gardeners with one of the most breathtaking sights in the flower garden.

Harvest

N/Ad

Days to harvest

📅

Sun

Full sun with afternoon shade in hot climates

☀️

Zones

3–7

USDA hardiness

🗺️

Height

3-5 feet

📏

Planting Timeline

Zone:

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Start Indoors

Transplant

Direct Sow

Start Indoors

Transplant

Direct Sow

Showing dates for Delphiniums Pacific Giant Series in USDA Zone 7

All Zone 7 flower →

Zone Map

Click a state to update dates

Delphiniums Pacific Giant Series · Zones 3–7

What grows well in Zone 7? →

Growing Details

Difficulty

Difficult

Spacing18-24 inches

SoilRich, fertile, well-drained soil with high organic matter

pH7.0-7.5 (slightly alkaline preferred)

WaterConsistent moisture, deep watering, good drainage essential

SeasonCool season perennial, often grown as annual in warm climates

FlavorN/A

ColorMixed colors including deep blue, light blue, purple, pink, and white

Size3-4 foot flower spikes with individual 2-3 inch florets

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
Zone 3	April – May	June – July	June – August	—
Zone 4	March – April	June – June	June – July	—
Zone 5	March – April	May – June	May – July	—
Zone 6	March – April	May – June	May – July	—
Zone 7	February – March	April – May	April – June	—
Zone 8	February – March	April – May	April – June	—
Zone 9	January – February	March – April	March – May	—
Zone 10	January – January	February – March	February – April	—

Complete Growing Guide

Soil: High Organic Matter. Soil pH: Alkaline (>8.0). Drainage: Good Drainage. Height: 3 ft. 0 in. - 5 ft. 0 in.. Spread: 2 ft. 0 in. - 3 ft. 0 in.. Spacing: 12 inches-3 feet, 3 feet-6 feet. Growth rate: Medium. Propagation: Seed. Regions: Mountains, Piedmont.

Harvesting

Bloom time: Summer

Edibility: Toxic if eaten.

Storage & Preservation

Fresh delphinium cuts should be processed immediately after harvesting for maximum longevity. Place stems in deep, cool water (around 40-50°F) and store in a cool location away from direct sunlight. They'll maintain quality for up to a week when properly conditioned.

For preservation, delphiniums excel at air drying due to their dense flower structure. Harvest spikes when flowers are just beginning to open, strip lower leaves, and hang upside down in small bundles in a warm, dry, dark location with good air circulation. They'll dry completely in 2-3 weeks, retaining much of their original color intensity.

Silica gel drying produces superior results for individual florets, maintaining better color and form. Press individual flowers in a flower press or heavy book between absorbent paper for craft projects. The dried flowers work beautifully in wreaths, potpourri, and permanent arrangements, though remember all parts remain toxic even when dried.

History & Origin

Origin: Europe to Mongolia

Advantages

+Disease resistance: Deer, Rabbits
+Attracts: Toxic if eaten.
+Wildlife value: Flowers attract hummingbirds and butterflies.
+Edible: Toxic if eaten.

Considerations

-Toxic (Flowers, Leaves, Stems): Medium severity
-Causes contact dermatitis

Companion Plants

Plant Together

Roses

Delphiniums provide natural support structure and both benefit from similar growing conditions

Larkspur

Similar care requirements and creates layered cottage garden effect with complementary flower forms

Peonies

Bloom timing complements delphiniums and both prefer rich, well-drained soil

Campanula

Provides ground cover and contrasting flower shape while sharing similar moisture needs

Astilbe

Thrives in partial shade created by tall delphiniums and adds textural contrast

Monkshood

Similar growing requirements and extends the blue color palette in the garden

Hollyhocks

Creates dramatic height variation and both are classic cottage garden plants

Catmint

Repels pests and provides low-growing complement to tall delphinium spikes

Keep Apart

Black Walnut

Produces juglone toxin that can severely damage or kill delphiniums

Crown Imperial Fritillaria

Allelopathic compounds can inhibit delphinium growth and establishment

Brassicas

Compete for similar nutrients and can attract pests that also damage delphiniums

Nutrition Facts

Calories

15kcal(1%)

Protein

1.03g(2%)

Carbs

3.28g(1%)

Fat

0.07g(0%)

Vitamin C

28mg(31%)

Vitamin A

97mcg(11%)

Iron

0.7mg(4%)

Calcium

39mg(3%)

Potassium

173mg(4%)

Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #169270)

Pests & Disease Resistance

Resistance

Susceptible to crown rot, bacterial black spot, and powdery mildew

Common Pests

Aphids, spider mites, slugs, snails, delphinium leaf miner

Diseases

Crown rot, bacterial black spot, powdery mildew, fusarium wilt

Frequently Asked Questions

How long does Pacific Giant delphinium take to bloom from seed?▼

Pacific Giant delphiniums typically take 5-6 months from seed to bloom when started indoors in late winter. With proper cold stratification and indoor starting 10-12 weeks before the last frost, expect spectacular flower spikes by mid to late summer. Second-year plants often bloom earlier and more prolifically in perennial zones.

Can you grow Pacific Giant delphiniums in containers?▼

While challenging, Pacific Giants can grow in very large containers (minimum 20 gallons) with excellent drainage and consistent moisture management. Use a deep pot to accommodate their long taproot, provide sturdy staking, and expect smaller mature size. Container growing increases disease risk, making this variety better suited for garden beds.

Are Pacific Giant delphiniums good for beginners?▼

Pacific Giant delphiniums are definitely not beginner-friendly. They require specific soil conditions, precise watering, cold seed stratification, careful transplanting, and consistent disease prevention. New gardeners should start with easier annuals and work up to delphiniums after gaining experience with soil preparation and plant care fundamentals.

When should I plant Pacific Giant delphinium seeds?▼

Start Pacific Giant delphinium seeds indoors 10-12 weeks before your last frost date, typically late January to early February in most regions. Seeds require 2-3 weeks of cold stratification in the refrigerator before sowing. In mild winter areas (zones 8-9), direct sow in fall for spring blooms.

How tall do Pacific Giant delphiniums actually get?▼

Pacific Giant delphiniums typically reach 6-8 feet in optimal conditions, with flower spikes themselves measuring 3-4 feet long. Height depends heavily on soil fertility, moisture consistency, and protection from wind. First-year plants from seed often reach 4-6 feet, while established perennial crowns achieve maximum height in subsequent years.

Why do my Pacific Giant delphiniums keep dying?▼

Crown rot from poor drainage or overwatering kills most Pacific Giant delphiniums. These plants need rich, well-draining soil that never stays soggy. Other common causes include planting in heavy clay, watering overhead instead of at soil level, insufficient air circulation, or extreme heat stress in southern climates without afternoon shade.