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The Navarre Garden Club, Flower of the Month for

DECEMBER 2004

Louisiana Giant Blue Flag Iris

Family: Iridaceae
Genus: Iris
Species: giganticaerulea

Photo courtesy Louisiana Iris Farms, LLC

The Louisiana iris group (known as the hexagonae series) is composed of five distinct species: Iris fulva, I. brevicaulis, I. nelsonii, I. hexagona, and I. giganticaerulea.

Louisiana iris has the distinction of having the greatest diversity of colors out of any iris group. Virtually every color of the rainbow is found in the flowers of these iris species. This is fortunate, as the name iris is derived from the Greek word meaning rainbow. Early French explorers to the Gulf of Mexico called the Louisiana iris "les glis de marais" or "glads of the marsh." The broad color range has made the Louisiana's one of the most popular irises in the world.

They can be found growing in the gardens of England, Australia, South Africa and New Zealand. Louisiana irises typically bloom from late March thru April, and best after a winter with a hard freeze. The striking vertical leaves of this herbaceous perennial make it a welcome addition to any garden bed.

Because irises bloom in the spring, combine with low growing summer and fall blooming perennials and annuals. Louisiana iris makes a great background plant for 'New Gold' lantana, verbena, pentas, coreopsis, and other flowering plants. Use Louisiana iris as accents and focal points for pond edges, stream banks and damp areas.

Louisiana Giant blue flag iris, or Iris giganticaerulea is found along the gulf coast in sunny marshes and swamps. It can range in height from three to six feet in height and has flowers ranging in color from pure white to deep velvety blues
Giant blue flag Louisiana iris are very easy to grow. They thrive in ditches, bogs, along pond edges, or in garden beds that stay moist and fertile. When planting in water, place the root ball no deeper than six inches below the water surface. When growing iris in the garden, provide thick mulch around the plants to ensure proper moisture and organic matter. The mulch also reduces the chances of sunscald on iris rhizomes (the horizontal plant stems that run along the ground).

Louisiana iris grows actively in the winter months until flowering, then goes into a state of dormancy in the summer as the heat arrives. It is normal during the summer dormant period for the leaves to yellow and wither.

Iris need at least six hours of full sunlight in order to bloom, preferably morning sun. In soil conditions with a pH greater than 6.0, yellow leaves and poor growth can occur. Fertilize the plants periodically during the winter with an 8-8-8 liquid or slow release fertilizer. If planted less than 4 ft. apart the plants will grow together in two-four years. At 4 ft. or more apart they will form nice clumps. This plant is attractive to bees and butterflies.

Propagate by dividing rhizomes, tubers, corms or bulbs (including offsets). Seed collection is accomplished by allowing pods to dry on plant; break open and collect seeds. Ripe yet soft seeds germinate readily, while hard, dry seeds may take over a year to germinate. Louisiana iris self-sow freely (deadhead if you do not want volunteer seedlings next season).

There are few serious insect and disease problems associated with Louisiana iris. Cutworms and leaf miners may damage the leaves of the plant, but do little harm to overall plant health. Many general-purpose insecticides may repel or control these insects. Iris rust is a foliar disease that causes brown spots to appear occasionally. This fungus does not harm the plant but may discolor the foliage. An excessive use of nitrogen fertilizer tends to stimulate the occurrence of iris rust.

Above information from Jim Carson, our Horticulture Chairman

Jim gives away Louisiana Giant Blue Iris plants at our December Meeting