Iris 'Professor Neil'

Common Name: Louisiana iris 
Type: Herbaceous perennial
Family: Iridaceae
Zone: 5 to 9
Height: 2.00 to 3.00 feet
Spread: 1.00 to 2.00 feet
Bloom Time: May to June
Bloom Description: Wine red
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Low
Suggested Use: Water Plant, Naturalize, Rain Garden
Flower: Showy
Attracts: Hummingbirds
Tolerate: Deer, Clay Soil, Wet Soil


Easily grown in average to rich, slightly acidic, moist to wet soils in full sun to part shade. Adaptable to different soils, climates and cultural practices. Prefers full sun, but appreciates some afternoon shade particularly in hot summer growing conditions. This is a water-loving iris. The wetter the soil, the more vigorous the growth. Deep watering is best. Grows well in up to 6” of standing water. Tolerates clay soils which retain moisture. Avoid well-drained sandy soils unless copious amounts of organic matter are added. Soils should never dry out during the growing season. Can be grown in pots sunk into the ground in water gardens. Can also be grown in elevated beds as long as adequate moisture levels are maintained.

Best planted in late spring (early May to early June). Fall planting (mid-August to mid-September) also works, particularly in areas with mild winters. Soak rhizome in water over night before planting. Keep tops of rhizome shallow (about 1” below the soil surface). A year-round mulch of pine needles around each plant with straw mulch added in winter (particularly in areas where the ground freezes in winter) will help keep the soils moist and protect the plant rhizomes from damage and/or sunscald. Propagate by division.

Noteworthy Characteristics

Louisiana iris is a catchall term used to describe a large group of rhizomatous beardless interspecific hybrid irises that contain varying percentages of the five species which make up the Louisiana Iris Group: Iris fulva, Iris hexagona, Iris brevicaulis, Iris giganticaerulea and Iris nelsonii. These irises will spontaneously hybridize in the wild. Species in the Louisiana iris group are native to the bayous and marshes, damp hillsides, swamps, and riversides of Southern Louisiana to Florida and the Carolinas north along the Mississippi River drainage to southeastern Missouri and southern Ohio. Notwithstanding the southern native territory of Louisiana iris, the hybrid cultivars available in commerce today are typically winter hardy to USDA Zone 5 (in some cases 4) and are currently being grown in most U.S. States.

Louisiana hybrids grow from 12-60” tall. Flowers come in a large variety of different colors and color combinations. Flowers bloom May-June. Flowers are usually slightly fragrant and attract hummingbirds. Each plant features linear, sword-like to grass-like, unribbed foliage. Foliage may go dormant in summer.

Louisiana iris became the State Wildflower of Louisiana in 1990.

Genus named for the Greek goddess of the rainbow.

The name Louisiana iris comes from an 1821 painting from John James Audubon’s Birds of America which features a pair of parula warblers perched on a flower stalk of a blooming Iris fulva plant.

‘Professor Neil’ is a Louisiana iris that typically grows to 2-3’ tall. Flowers bloom May-June. Hybridized by Joseph Mertzweiller. Registered in 1990. Dark red standards and dark red falls with bright yellow signal. Musky fragrance.


Leaf spot, bacterial soft rot, root rot, iris rust and mosaic viruses may appear. Watch for slugs, snails, cutworms, whiteflies, leaf miners, aphids and thrips. Iris borers can cause significant problems in areas where they are found. Deer tend to avoid this plant


Water gardens, bog gardens, pond or stream margins, or moist low spots. Ideal for growing in pots sunken into fishponds or water gardens.