Louisiana iris refers to five naturally occurring species in the Series Hexagonae of the Genus Iris. The term also includes hybrids created through human-assisted cross-pollination or naturally when the species grow in proximity.
Together, these irises form a diverse, adaptable, and vibrant group of plants well-suited to gardens across much of the United States. They are right at home around New Orleans and the Gulf Coast.
Although they were virtually unknown in horticulture a century ago, many gardeners now grow and enjoy Louisiana irises. However, despite significant strides in recognition, they are not yet as widely known and appreciated as they deserve to be. Even after years of promotion, many people still exclaim, “I had no idea they came in so many colors.”
Along the Gulf Coast, Louisiana irises typically begin blooming in mid- to late March and continue through late April. Weather conditions can shift the season by a week or more, but some irises generally bloom earlier and others later in the season. Peak bloom often arrives in early April, when the greatest number of species and hybrids flower at once.
Occasional bloom stalks may appear in late fall or winter. These off-season stalks are unpredictable, usually bear fewer flowers, and are vulnerable to freeze damage. They’re a welcome surprise, but the true and reliable display belongs to spring.
Louisiana iris species occur in wet environments, though the degree of inundation varies by species. At one extreme, Iris giganticaerulea (the tall blue) grows in the wettest settings, including wooded swamps and open freshwater marshes. At the other end of the spectrum, Iris brevicaulis prefers low, mucky ground but not standing water.
Modern hybrids are remarkably adaptable and perform well in conditions ranging from water gardens to consistently irrigated beds. While they tolerate a variety of settings, like the species, they do not like to dry out. In general, the wetter Louisiana irises remain, the better they grow.
Louisiana irises grow from rhizomes rather than bulbs. Rhizomes are horizontal, creeping underground stems that produce roots from their underside, beginning at the growing tip and extending along most of their length as long as moisture and soil conditions are favorable. Bulbs, by contrast, are rounded structures made up of layered scales surrounding a central point, with roots emerging from the base.
Remember this: it is not cool to say “bulbs” when speaking of Louisiana irises. Think rhizomes!
Vegetative reproduction. Rhizomes produce offsets along their length, either near the growing tip or along the sides, creating identical clones of the parent plant. Over time, this branching forms clumps that can become quite large. Dividing these clumps is the primary way to increase or maintain a particular iris. An individual rhizome blooms only once; the offsets bloom in subsequent seasons. A spent rhizome can be removed, cut into sections, and potted to produce new offsets identical to the parent.
Sexual reproduction. When flowers are pollinated—by bees, humans, or occasionally hummingbirds—seed capsules form, containing corky, buoyant seeds. In the wild, these seeds disperse by floating away as the capsule breaks down.
In many plant groups, species that cross at all produce sterile offspring. This is not the case with the closely related Louisiana iris species. Pollen from Iris giganticaerulea, for example, can fertilize Iris fulva, and the resulting hybrid is fully fertile—capable of backcrossing with either parent or interbreeding with other hybrids.
This natural compatibility is responsible for the extraordinary range of colors and forms seen in Louisiana iris hybrids. Hybridization has both incorporated and amplified the considerable genetic variation already present within the species.
The core, shared characteristics of the Louisiana irises are a good starting point for an fuller exploration of these fascinating plants. Continue your journey in the areas of most interest.
A surprisingly recent and fascinating story
Pages on the wild Louisiana irises native to the State
The astounding changes that hybridization has wrought (coming soon)
Advice on how to grow the irises in varying conditions
How to get irises from irises.
They can only wish they were Louisiana irises (coming soon)
Coming Soon