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PlantFiles: Giant Blue Flag Iris
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 fluviatilis
Synonym:Iris miraculosa
Synonym:Iris rivularis
Synonym:Iris venulosa

» View all varieties of Iris

One vendor has this plant for sale.

15 members have or want this plant for trade.


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
Medium Blue
Dark Blue
White/Near White

Bloom Time:
Midseason (M)


Other details:
May be a noxious weed or invasive
This plant is attractive to bees, butterflies and/or birds
Flowers are fragrant
Requires consistently moist soil; do not let dry out between waterings
Very high moisture needs; suitable for bogs and water gardens
Self-sows freely; deadhead if you do not want volunteer seedlings next season
This plant may be considered a protected species; check before digging or gathering seeds

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)

Seed Collecting:
Allow pods to dry on plant; break open to collect seeds

Awards (if applicable):
Unknown - Tell us

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4 positives
No neutrals
No negatives

Gardeners' Notes:

Positive seedlng 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 creek area of broward county. I live inland from the beach.

in south east florida swales are used along streets to collect
heavy rain and drain them into the canals designed to prevent flooding city streets.

most swales are not used because i think alot of folks
dont know what to do with them.

Ordinances state no trees or planting that will prevent vehicles from seeing pedestrian traffic. so most plants have to be under a certain footage. and not in the center of the swale.

I designed a 2 ft wide strip along the city sidewalk and the swales to handle plantings or irises, grasses and such. i have 4 ft bedding of blue flag iris and white lirope grasses along the area bordering the driveway , swale and side -walk, with plantings that will not interfere with waterflow and possibly help suck up the moisture as sometimes the heavy rains do stand, flooding streets for a day or two.

lousiana iris , blue flag iris, african iris (yellow and white) green and white liriope, rain lillies and blue daze along with other small perennials.

much to my surprise the first season, the blue flag iris wilted and died out. This year however, it has re claimed its place and has been growing with abandoned glory. it has not taken any particular care, othern then pruning out the dead leaves which is not frequent.

I think the key to growing them , here in south east florida in this particular siutuation is to, allow them to grow into their location. it has proven to be very strong. the summers are extremely hot , rainy and humid. winters are dry , sunny and cool sometimes. in the winters when it is droughty the iris does tend to die back a bit. but the iris re-claims its place
once the conditions for mositure continues to grow.

I practice xeriscape, low maintenance and some native gardening. most of all I experiement. using natives as my bones of the garden. blue flag works well here...

Positive MotherNature4 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.

Positive suncatcheracres 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 Mississippi River Delta, and in areas around St. Martinville near Lafayette in Southwest Louisiana (also near Cade, where my Grandmother was born) and near the Texas-Louisiana border. These collected natural species and hybrids were used extensively by early collectors and hybridizers to produce the fantastic modern Louisiana iris hybrids of today, but unfortunately many of the original species and hybrids have been lost, due to drainage of natural wetlands that comes with suburban growth and industrialization.

But modern DNA techniques can now tell us something about the parentage of the modern plants, and I. giganticaerulea shows up prominently. It was the most plentiful of the five original species of Louisiana iris, and "great numbers were collected and used in hybridization," contributing doubles, semi-doubles, and cartwheels, or 'all-falls,' type flowers.

I. giganticaerulea, true to its name, can reach close to six feet tall, and it contributed many pure whites to the modern hybrids. Blues and blue-purples were other common colors of the original I. giganticaerulea species, and the showy flowers were born above the foilage, with double flowers at the top, and singles along the stem. "Her Highness,' a self white with green style arms, is one of only two collected (found growing in the wild) Louisiana Iris to win the prestigious DeBaillon Award, in 1959, and I. giganticaerulea may have contributed its white color to the famous 'Clara Goula' variety of I. nelsonii, with large, ruffled creamy white flowers, and another DeBaillon Medal winner in 1987. I have 'Clara Goula' currently growing in my garden in a rich, moist, sunny bed with tall cannas.

Positive dogbane 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.

Some botanist argue that this is a variety of I. hexagona, which has a much wider range but lacks the stature and large flower size of I. giganticaerula.

Hummingbirds frequent these flowers but bumble bees do the pollinating. The flowers have what some consider a strong and not altogether pleasant scent, but I think it works well outdoors.

Seeds have a cork-like coat. Ripe yet soft seeds germinate readily. The hard, dry seeds may take over a year to germinate.


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)
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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