Species Iris, Giant Blue Iris, Giant Blue Flag

Iris giganticaerulea

Family: Iridaceae (eye-rid-AY-see-ee) (Info)
Genus: Iris (EYE-ris) (Info)
Species: giganticaerulea (jy-gan-tee-see-ROO-lee-uh) (Info)
Synonym:Iris aurilinea
Synonym:Iris citricristata
Synonym:Iris elephantina
Synonym:Iris fluviatilis
Synonym:Iris miraculosa
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Species (SPEC)


4-6 ft. (1.2-1.8 m)


9-12 in. (22-30 cm)


USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

Sun Exposure:

Full Sun

Sun to Partial Shade


Parts of plant are poisonous if ingested

Bloom Color:

Pale Pink



Light Blue

Dark Blue

Medium Blue



Medium Purple

White/Near White

Bloom Time:

Midseason (M)



Other details:

May be a noxious weed or invasive

Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

Patent Information:


Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

Self-sows freely; deadhead if you do not want volunteer seedlings next season

Seed Collecting:

Allow pods to dry on plant; break open to collect seeds

Awards (if applicable):

Unknown - Tell us

Foliage Color:

Unknown - Tell us

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Flowers are fragrant

Water Requirements:

Requires consistently moist soil; do not let dry out between waterings

Very high moisture needs; suitable for bogs and water gardens

Where to Grow:

Unknown - Tell us


This plant has been said to grow in the following regions:

Fort Lauderdale, Florida

Old Town, Florida

Panama City, Florida

Kuna, Idaho

Coushatta, Louisiana

Franklin, Louisiana (2 reports)

Gonzales, Louisiana

New Orleans, Louisiana

Pollock, Louisiana

Rochester, New York

Webster, New York

Jefferson, Ohio

Beaumont, Texas

Broaddus, Texas

Houston, Texas (2 reports)

Shepherd, Texas

Tomball, Texas

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Gardeners' Notes:


On Jun 16, 2005, seedlng from Fort Lauderdale, FL wrote:

Fort Lauderdale: Florida ( south - east florida )

This Blue Flag Iris works well here...

Northerns who have moved to florida, looking for an iris that is similar to what they are used to seeing up north, try this one.

I purchased mine from the web online.
It looked very tiny when I received this iris through the mail, but since it appeared in good health and had good roots.

if you live in florida and are researching plants to include in a rain garden, or planting group in our common street side swales created to improve water flow to our many drains that collect and wash out to canals build to handle our rain and flooding, --try this.

I am a garden designer, just moved into a home in
cypress cree... read more


On Apr 9, 2005, MotherNature4 from Bartow, FL (Zone 9a) wrote:

They're blooming in Polk County, central Florida, right now and they're breathtaking.


On Nov 24, 2003, suncatcheracres from Old Town, FL wrote:

The Irises are another example of why we need exact botanical names, as 'Blue Flag' is a term used for several different iris plants in the South. The 'Great Blue Flag,' or 'Southern Blue Flag,' Iris virginica, is found all over the Southeastern US, and can reach 6 feet tall. The 'Blue Flag,' Iris versicolor, is a shorter natural hybrid of I. virginica. In Florida, I. hexagona, one of the original five Louisiana iris species, is also called the 'Dixie' iris as well as 'Giant Blue Flag,' and is extensively used in wetland restoration, as it will form huge clumps.

Thousands of species and natural hybrids of Louisiana iris were collected in the 1930's and 1940's from the wild, and I. giganticaerulua was found by collectors growing naturally near the New Orleans area and the ... read more


On Nov 23, 2003, dogbane from New Orleans, LA (Zone 9a) wrote:

This is one of the native parents of the 'Louisiana iris'.

Naturally found in marshes and swamps, this species is ideally suited for water garden. In it's natural range, the foliage begins growth in early to mid fall, blooms appear around April and the foliage usually goes dormant in the summer. However, it performs remarkably well in a perennial border. Tends to "wander" in the garden, proliferating in the right conditions. Reproted to grow well far outside of its natural range.

The flowers vary highly in color and can be found in the wild in nearly any part of the spectrum from white to dark purple. Reds and yellows are not indicative of this species, but since it hybridizes in nature with I. fulva and I. nelsonii those colors may appear.
... read more