GNOIS Logodormon podsSLI

propagation strategy

This is the "how to" page for GNOIS conservation activities.

It's easy to endorse conservation but more complicated to craft achievable steps to promote it. The Conservation and Education Program adopted by GNOIS designed to make a meaningful contribution to the preservation of Louisiana's unique legacy of irises. This page briefly oulines the GNOIS approach. (A more detailed description of the plan is available here as a pdf file).

The conservation activities of GNOIS rest on the twin pillars of Preservation and Propagation. The Preservation pillar is well constructed already. Building on it, the Propagation pillar has begun to take shape.

Preservation.  GNOIS has participated since 2017 in the Louisiana Iris Species Preservation Project (SPP) sponsored by the Society for Louisiana Irises and described on an adjoining page. At its “nursery” in New Orleans City Park, GNOIS grows around 150 distinct, naturally-occurring forms of our five species of wild irises.  They exhibit many shades of blue, red, yellow, white, purple, and hard-to-describe “in-between” colors.  The GNOIS collection is more extensive than those on the core “preservation list” of the SPP and includes natural hybrids between species found in the wild.

conservation project outline

Propagation. The collection of irises assembed for the Species Preservation Project form the basis from which large numbers of new plants — reflecting the full diversity of wild Louisiana irises — can be produced by propagation. Propagation can occur through two methods: seed production and rhizome division and cuttings. The GNOIS approach will utilize both methods, and the resulting irises will be used in a variety of projects similare to those already implemented: in nature preserves, parks, rain gardens, an other places where they provide both education and enjoyment for the public. They also can be used in "restoration" projects: locations where the irises once grew but were destroyed and "new" land created by coastal restoration, such as through Mississippi River diversions.

Propagation from seed requires that we make "controlled" crosses in which a volunteer uses the pollen from one species of the five species of Louisiana irises to pollinate a flower of the same species. This assures that the resulting plants grown from seed are "true" representatives of a given species. (Bees spread pollen randomly among species growing in proximity, and resulting seeds will produce plants that are usually hybrids rather than pure example of any one species.)

Louisiana irises produce seeds prolifically.  A seed pod may contain from 20 to 80 seeds, and one bloom stalk might yield one to four or five pods. If half of the seeds collected germinate, one blooming iris might yield 75 to 100 new plants from a single season.  If these new irises are themselves harvested for seeds in subsequent years, the number of available plants can increase exponentially.

Propagation from rhizome division and cuttings is a way to easily produce new plants genetically identical to the "mother" iris. For a cutting, a two and a half inch section of an iris rhizome is placed in a well-draining medium. It usually will produce several "offsets" that will grow into mature plants far in excess of the natural rate of multiplication. 

rhizome as dug
rhizome cut
potted pieces
new starts


Without taking cuttings, additional plants also can be produced simply by separating the offsets produced by natural increase from rhizomes. If the divided irises are provided a fertile place to grow, the stock of the plant can be increased significantly without other steps.


These methods of propagation are in their early stages, and when fully ramped-up will they will supply the most diverse source of authentic, native Louisiana irises available for various plantings and other projects.

The Species Preservation Project collection in City Park positions GNOIS to develop a diverse array of Louisiana irises unmatched in the country.  No other source exists for as many unique forms and colors of Louisiana iris species.


To date, planting projects have generally drawn upon irises “rescued” from one location and replanted in another.  Such opportunities arise occasionally, and it is entirely appropriate to take irises from a place where they are endangered and plant them elsewhere.  While GNOIS will not ignore such opportunities, plant rescues will not be the vehicle for the routine operation of the GNOIS Conservation Program in the future.  For several reasons, propagation has advantages as the core strategy to produce irises for plantings:

prop vs rescue


The objective of the propagation strategy is to add to the capacity of GNOIS members to effectively promote preservation and conservation of our native irises.  It creates a new and sustainable approach rather than replacing other opportunities, such as rescues, that may arise.  Propagation strategies, hopefully, can engage a more substantial proportion of our members in conservation efforts and bring them to the island nursery in regular, comfortable, and supporting roles.

GNOIS is in the process on expanding and enhancing the propagation process in its planting in City Park. Reports of progress will be posted, and members can expect to be invited to volunteer to help.