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Delphinium menziesii (Menzies' Larkspur)
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© Steve Hampton, some rights reserved (CC-BY-NC) · iNaturalist

Delphinium menziesii

Menzies' Larkspur

Pacific coast of western North America

At a Glance

HabitUpright
FoliageDeciduous
Height6-20 inches (15-50 cm)
Width4-8 inches (10-20 cm)
Maturity4 years

Growing Zones

USDA Hardiness Zones

6 - 9
These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →
Frost Tolerancehardy

Overview

A clump-forming herbaceous perennial reaching 6-20 inches (15-50 cm) tall and 4-8 inches (10-20 cm) wide, arising annually from a short tuberous rootstock. Basal and lower stem leaves deeply palmately divided into 5-7 narrow lobes, each lobe further cut into linear segments 0.1-0.2 inch (3-5 mm) wide; foliage withers as flowering ends. Flowering stems carry 5-15 flowers in an open raceme; individual flowers deep blue-purple, 0.75-1.25 inches (1.9-3.2 cm) across, with five sepals (the upper extended into a 0.5-0.75 inch (13-19 mm) spur) and four smaller petals — the upper two whitish and prominent. Flowering occurs April through June depending on elevation. Plants enter summer dormancy by July, with foliage dying back to the rootstock; new growth resumes the following spring. Seedlings reach flowering size in 3-4 years from spring sowing. All parts contain diterpenoid alkaloids; livestock losses occur regularly across western rangelands where the species grows. Plants are short-lived in garden cultivation outside their native climate, with most stands declining within 3-5 years on irrigated soils.

Native Range

Native to western North America from coastal British Columbia south through Washington and Oregon to northern California, with inland populations east to western Idaho. Found in open coniferous woodlands, oak savanna, coastal bluffs, and grassy slopes from sea level to 7,500 feet (2,300 m).

Suggested Uses

Planted in dry meadow plantings, native woodland gardens, and unirrigated borders within its hardiness range, at 8-12 inch (20-30 cm) spacing. Stands occupy cracks between rocks and along path edges where summer drought is reliable. Container culture is rarely successful beyond 2-3 years because crown rot follows even moderate summer watering.

How to Identify

Separated from D. nuttallianum by typically taller stature (often 12-20 inches / 30-50 cm versus 4-12 inches / 10-30 cm) and broader leaf segments 0.1-0.2 inch (3-5 mm) wide. Flowers deep blue-purple with whitish upper petals, in a loose raceme of 5-15 blooms; the spur is straight to slightly curved and 0.5-0.75 inch (13-19 mm) long. Roots are short and tuberous, not deeply taprooted; seedlings produce a single divided cotyledon in their first year. Flowering stems senesce by mid-summer, leaving no above-ground tissue.

Appearance

Size & Dimensions

Height6" - 1'8"
Width/Spread4" - 8"

Reaches mature size in approximately 4 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~5 weeks
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April through June at low elevations, with peak flowering in May. Higher-elevation populations may bloom into early July. Total bloom period per stand lasts 3-5 weeks; individual flowers persist 5-7 days. Cool, wet springs extend bloom by 1-2 weeks.

Detailed Descriptions

Flower Description

Deep blue-purple with whitish upper petals

Foliage Description

Mid-green

Growing Conditions

Sun Requirements

Requires 5-9 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 Range6.0 - 7.5(Neutral)
357912
Soil Types
Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

3-4 years from seed

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plants benefit from supplemental water during the first growing season after planting; established plants need no irrigation once foliage senesces in early summer. Crown rot develops in summer-irrigated beds and is the primary cause of stand decline in cultivation. Slugs damage emerging foliage in March and April in coastal climates. Seeds require 6-10 weeks of cold stratification at 32-40°F (0-4°C) before germination and are commonly autumn-sown for natural stratification. All parts contain diterpenoid alkaloids; ingestion can be lethal to cattle, horses, sheep, and humans, with no reliable treatment for severe poisoning. Most stands decline by year 3-5 in non-native climates and are maintained by replacement seeding rather than long-lived plants.

Pruning

Spent flower stems can be removed once seed disperses if self-seeding is not desired. Withering foliage is left in place after summer dormancy as it pulls free with light tugging in autumn. Cutting back during active growth slows recovery, as wounds on stems and leaves bleed sap that does not seal quickly in dry summers.

Pruning Schedule

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summer

Maintenance Level

low

Container Growing

Minimum container size: 1 gallons

⚠️ Toxicity Warning

Toxic to pets and humans