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Species photo — your cultivar may vary

Iris, Genus, sibirica, Species, 'Caesar's Brother', Cultivar,

Genus & species
Cultivar

Caesar's Brother Siberian iris

Iridaceae

Garden selection; species {Iris sibirica} is native to central and eastern Europe and temperate Asia

Attracts Pollinators Attracts Butterflies Attracts Hummingbirds Deer Resistant Drought Tolerant Container Friendly

SunFull Sun – Part Shade

WaterMedium · drought-tolerant

HardinessZones 3–8

Overview

Iris sibirica 'Caesar''s Brother' is a Siberian iris cultivar grown for very dark violet-blue to near-black flowers, forming an upright clump 30–36 inches (75–90 cm) tall and 24–30 inches (60–75 cm) wide. Three-petaled flowers 3–4 inches (8–10 cm) across with deep violet-blue falls and standards and a small yellow-white signal patch at the base of each fall appear from mid-May through mid-June for about 3 weeks; flower color sits darker than the typical mid-blue Siberian iris and approaches near-black at full opening. Foliage is composed of medium green narrow sword-shaped leaves 24–30 inches (60–75 cm) long that arch outward from the central crown, holding form through summer and turning golden-brown after the first hard frost. Cultural advantages over tall bearded iris (I. germanica) include tolerance of moist to wet soils, no susceptibility to iris borer, no need for staking at this height, and clump intervals of 5–8 years between divisions rather than the 3–4 years typical of bearded iris. The clumping habit stays in place rather than running by rhizomes, so the plant remains where it is set. The species I. sibirica is native to wet meadows and stream margins of central and eastern Europe and temperate Asia. All parts contain irritant compounds that can cause skin and gastrointestinal reactions in pets and humans. Deer rarely browse iris foliage.

Native Range

The species Iris sibirica is native to central and eastern Europe and temperate Asia, with a range from northern Italy and the Alps east through Russia to Lake Baikal, where it grows in wet meadows, marshes, and along stream margins. I. sibirica 'Caesar''s Brother' is a garden selection introduced in the 1930s, chosen for very dark violet-blue flower color.

Suggested Uses

Used in mixed perennial borders, along the margins of ponds and streams, in rain gardens with reliably moist soil, in mass plantings, and in containers of 7 gallons (26 liters) or larger. The arching grass-like foliage holds form through the summer growing season after the spring bloom finishes, contributing structural texture to mixed plantings. Combines with Hemerocallis, Astilbe, and grasses such as Calamagrostis for moist-border plantings.

How to Identify

Look for very dark violet-blue to near-black three-petaled iris flowers 3–4 inches (8–10 cm) across with small yellow-white signal patches at the base of the falls, carried on slender stems above an upright clump of medium green narrow sword-shaped leaves 24–30 inches (60–75 cm) long. Flower color darker than the mid-blue typical Siberian iris separates I. sibirica 'Caesar''s Brother' from lighter blue cultivars in the same species; smooth (beardless) falls and the narrow grass-like foliage separate Siberian iris from bearded iris (I. germanica), which carries fuzzy beards on the falls and wider sword-shaped leaves.

Appearance

Size & Dimensions

Height2'6" - 3'

Width/Spread2' - 2'6"

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~3 weeks

Flowers: May–June

Spring Summer

Flowers from mid-May through mid-June for approximately 3 weeks across USDA zones 5–7; bloom shifts about 2 weeks earlier in zone 8 and later in zone 4. Very dark violet-blue to near-black flowers with yellow-white signal patches. Carries no perceptible fragrance.

Detailed Descriptions

Flower Description

Very dark violet-blue to near-black with small yellow-white signal patches at the base of the falls

Foliage Description

Medium green narrow sword-shaped leaves 24-30 inches (60-75 cm) long arching from the central crown

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 5-10 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 Range5.5 - 7.0 (Acidic to neutral)

3579

Soil Types

loam clay

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plant in a site receiving 5 or more hours of direct sun daily; clumps tolerate light shade but flower count drops below 5 hours. Soil should be moist to wet, slightly acidic to neutral (pH 5.5–7.0), and tolerates clay better than tall bearded iris. Water during the first season of establishment and during prolonged summer drought thereafter. Top-dress with compost in early spring; the plant responds to moderate fertility. Lift and divide only when the clump center dies out, typically every 5–8 years, in early fall or just after spring bloom finishes.

Pruning

Cut spent flower stalks at the base after bloom finishes in late June if seed-pod development is not wanted. Cut all foliage to 2 inches (5 cm) above the crown in late autumn after the leaves brown, or in early March before new growth pushes; the golden-brown autumn foliage may be left standing through winter for cold-season form.

Pruning Schedule

Prune: March & November

fallearly spring