Delphinium Hybrids, delphinium
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Perennials

Delphinium Hybrids

delphinium

Ranunculaceae

Northern Hemisphere; primary parent species from central Europe and Siberia

At a Glance

TypePerennial
HabitUpright
FoliageDeciduous
Height3-8 feet (90-240 cm)
Width2-3 feet (60-90 cm)

Growing Zones

USDA Hardiness Zones

3 - 7
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Attracts Pollinators
Attracts Hummingbirds
Deer Resistant
Maintenancehigh

Overview

A group of tall, clump-forming perennials in the family Ranunculaceae, derived primarily from Delphinium elatum and related species, encompassing thousands of named cultivars. Plants produce stout, upright stems 3–8 feet (90–240 cm) tall, clothed in large, deeply palmate-lobed leaves 3–6 inches (8–15 cm) across. Flowers are arranged in dense, erect racemes 12–36 inches (30–90 cm) long. Individual flowers 1–2 inches (2.5–5 cm) across have five petal-like sepals surrounding a small central cluster of modified petals called the bee, often in a contrasting color. The color range includes white, cream, pale pink, lavender, mid-blue, deep blue, violet, and purple; true blue shades are among the most sought-after in the horticultural world. All parts of the plant are toxic if ingested. Delphiniums are cool-season plants that perform best in cool summers; they decline rapidly in heat and humidity and are generally short-lived (2–4 years) in zones 7–8. Staking is required for all tall types.

Native Range

Garden hybrid delphiniums are predominantly derived from D. elatum, native to subalpine meadows and open woodland margins across central and eastern Europe and Siberia, as well as contributions from D. cardinale, D. nudicaule, and other species. The genus Delphinium comprises approximately 300 species distributed across the Northern Hemisphere and Africa.

Suggested Uses

Planted at the back of mixed perennial borders at 24–36 inch (60–90 cm) spacing, providing dramatic vertical accents in June. Classic companions include roses and peonies in the cottage garden tradition. Cut flowers last 5–7 days in water; cut when the bottom third of the spike is open. Not suited to hot, humid climates; performs best in zones 3–6 and the coastal Pacific Northwest.

How to Identify

Identified by large, deeply palmate-lobed leaves and tall, dense racemes of spurred flowers with a prominent spur projecting from the back of each flower. The bee — a central cluster of smaller petals often in a contrasting color — is visible at the center of each flower. Erect, hollow stems 3–8 feet (90–240 cm) tall and predominantly blue to purple coloring are characteristic, though white and pink forms exist.

Appearance

Size & Dimensions

Height3' - 8'
Width/Spread2' - 3'

Colors

Flower Colors

white
pink
lavender
blue
violet
purple

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~6 weeks
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SummerFall
Blooms June through July in zones 3–7; peak bloom in June in most temperate climates. A second, lighter flush of bloom is possible in September if plants are cut back to 12 inches (30 cm) immediately after the first bloom fades and watered and fertilized to encourage new growth. In zones 8–9, quality declines significantly and plants are often treated as cool-season annuals.

Detailed Descriptions

Flower Description

white, pink, lavender, blue, violet, purple

Foliage Description

medium green

Growing Conditions

Sun Requirements

Full Sun
Requires 6-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.5 - 7.5(Neutral)
357912
Soil Types
loamclay
Drainage
well drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

1-2 years

Care & Maintenance

Care Guide

Plant in full sun in deep, fertile, well-drained soil with a pH of 6.5–7.5; delphiniums are heavy feeders and require rich soil with ample organic matter. Stake stems when they reach 12–18 inches (30–45 cm) — do not wait until taller, as wind damage to unstaked stems is the most common cause of plant loss. Water deeply and regularly; do not allow soil to dry out. Fertilize every 3–4 weeks during the growing season with a balanced fertilizer. After first bloom, cut spikes back to 12 inches (30 cm) and fertilize to encourage a fall rebloom. Slugs are a serious pest — protect emerging shoots in spring with slug controls. In zones 7–8, treat as short-lived perennials and replace every 2–3 years.

Pruning

Cut spent flower spikes back to 12 inches (30 cm) immediately after bloom fades to encourage a second flush of bloom in September. After the second bloom, or in late fall, cut all stems to ground level. Do not leave hollow stems standing through winter as they collect water and promote crown rot. Divide in early spring every 2–3 years; replant vigorous outer sections and discard the old center.

Pruning Schedule

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summerfall

Maintenance Level

high

⚠️ Toxicity Warning

Toxic to pets and humans