By Joe Musacchia
The Louisiana
Iris is one of the most misunderstood yet versatile irises. It’s been called a
water iris, which is not technically correct. Some will grow in water, some will
not. If the foliage is totally submerged, they will most likely die. Most will grow
well in bog conditions, but some will not. They have been grown from Canada to
Mexico and in many countries abroad. They grow from the marshes and swamps of
Louisiana to the deserts of Arizona. The
secret to their successful cultivation is understanding the cultural
differences of the five species that make up this diverse group of iris, and
being able to recognize these traits. The species that make up Louisiana iris
are I giganticaerulea, I fulva, I
brevicaulis, I nelsonii, and I hexagona. Most of the new cultivars on the
market today have all 5 species genes in them. My purpose here is to help you to look at a cultivar
and recognize these traits, so that you will have some idea how this cultivar will
perform in your garden and what culture requirements are best.
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| I. giganticaerulea |
Iris giganticaerulea (or giant blue) is
the tallest of the Louisiana Irises. It can grow
over 6 feet tall in the right conditions. It was discovered and named by Dr.John K. Small in 1925 while he traveled by train through South Louisiana.
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| Iris giganticaerulea growing on a bayou side |
In its native area I. giganticaerulea grows all winter. Hot, dry summers may bring on dormancy, with the plant all but disappearing until late August when the weather cools, and rains return. It is most commonly found in marshes, along bayou banks, in ditches, and the edges of swamps. It can be seen growing in as much as 2 feet of water. Even so, if the plant goes dormant during the summer, an early return of standing water can spell their demise if the growing tip is submerged for an extended time.
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| White I. giganticaerulea ( Barbara Elaine Taylor ) |
I. giganticaerulea blooms very early in the spring
with rapid bloom stalk development. The flowers are very large, generally 4-6
inches across. The color is a blue-purple with an underlying white. A white
form, lacking the blue pigment, has been collected in the wild and brought into
cultivation. They require a lot of sun during their growing season (winter in
Louisiana), but will tolerate some light or afternoon shade in the peak of
summer in that region. They possess tall, straight stalks with little or no
branching. Their rhizomes tend to be large, and will often grow a foot or more
in a growing season, causing the plant to travel.
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| One year winter growth |
I. giganticaerulea’s core traits have an implication on their performance in various
geographic locations. Because they bloom early, hybrids that have strong giganticaerulea traits may not perform
as well in areas outside their normal range. Most commonly, unless the rhizomes
are directly exposed to extreme temperatures (as in the case of frost heave),
the plant will survive and grow, but might never produce bloom. In New York
State for example, where spring freezes are common, the tender, early bloom
stalk will succumb to the assault. You will get a lot of lush green foliage all
summer, but no flowers. Between the early bloom season, the tendency for the
rhizomes to travel in beds, not to mention the need for division every two or
three years, some find them a difficult plant to employ in a home landscape.
These same traits make them ideal for landscaping around ponds, rain gardens
and areas where too much water is a problem. Recognizing these traits in modern
hybrids can help you select the best Louisiana cultivar for success.
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Damaged rhizomes showing increase
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| Benny Trahan shows off an almost 7ft I. giganticaerulea |
Coming Up: The Traits of I. Fulva
