Instructions for Growing Perennial Louisiana Irises
Once you receive your rhizomes, it's important to follow instructions to ensure you're growing your Louisiana irises properly. To make this process easier for you, we've provided details on how to care for your plants from the Lousiana State University Agcenter Horticulturist, Heather Kirk-Ballard, so that they can provide limitless years of flowers. We follow the LSU Agcenter suggestions and have had excellent results. Many websites vary in their opinions on how to plant and grow irises.
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Lousiana State University Agcenter
The Louisiana iris (Iris spp.) has been named the spring 2022 Louisiana Super Plant selection by the LSU AgCenter. It comes as no surprise to Louisianians that this native beauty is worthy of this title. No other flower conjures thoughts of Louisiana more than the iris, except maybe the southern magnolia. This herbaceous, semi-evergreen perennial grows best in full sun but will perform well in partial shade. Blooming begins in late March and continues through May, and flowers come in a wide range of colors. Plants actively grow beginning in the fall in October through early summer. The Louisiana iris has a dormant period at the end of summer in August through October. This is the best time to divide clumps of iris. Overcrowded areas will not be as healthy and can diminish flower production. This iris spreads by rhizomes — continuously growing, horizontal, underground stems that put out shoots and adventitious roots at growing points. These can be cut into individual portions so long as the section has at least one growing point. |
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Division of clumps should be done during the dormant period in late summer. Divided clumps can be shared with friends and neighbors, relocated to a new location in the garden or planted in containers. Louisiana irises also can be planted successfully in the spring from containers purchased at retail garden centers.
There are five main species of Louisiana iris: Iris fulva, I. brevecaulis, I. hexagonaI, I. nelsonii and I. giganticaerulea. Hundreds of cultivars and hybrid crosses have occurred both naturally and as a result of breeders seeking unique flower colors.
Irises are an excellent selection for low areas that hold water because they are so water tolerant. Additionally, they make a good selection for rain gardens and can be planted along the banks of ponds or lakes to help stabilize the soil. Plants do well also in containers and in raised garden beds.
There are few pest and disease issues associated with the Louisiana iris. The plant disease rust can affect it and typically shows up as tiny red or dark brown spots with yellow margins on the leaves and stems of the plants.
Rust often appears in early summer after flowering has stopped. The disease does not typically kill plants and because it shows up after flowering has completed, it is not necessary to treat. Fungicides such as an organic copper can be used to help control it in heavily affected plants.
Caterpillars, iris borers, leaf miners, snails and slugs can sometimes be a problem. Most do not cause severe damage, and plants typically bounce back with no issues. In severe infestations, you can use a systemic pesticide but follow the label directions strictly. You also can try organic options. Remember, insecticides not only control the pest problems, but they may also harm pollinators.
There are five main species of Louisiana iris: Iris fulva, I. brevecaulis, I. hexagonaI, I. nelsonii and I. giganticaerulea. Hundreds of cultivars and hybrid crosses have occurred both naturally and as a result of breeders seeking unique flower colors.
Irises are an excellent selection for low areas that hold water because they are so water tolerant. Additionally, they make a good selection for rain gardens and can be planted along the banks of ponds or lakes to help stabilize the soil. Plants do well also in containers and in raised garden beds.
There are few pest and disease issues associated with the Louisiana iris. The plant disease rust can affect it and typically shows up as tiny red or dark brown spots with yellow margins on the leaves and stems of the plants.
Rust often appears in early summer after flowering has stopped. The disease does not typically kill plants and because it shows up after flowering has completed, it is not necessary to treat. Fungicides such as an organic copper can be used to help control it in heavily affected plants.
Caterpillars, iris borers, leaf miners, snails and slugs can sometimes be a problem. Most do not cause severe damage, and plants typically bounce back with no issues. In severe infestations, you can use a systemic pesticide but follow the label directions strictly. You also can try organic options. Remember, insecticides not only control the pest problems, but they may also harm pollinators.
Irises can be fertilized in the fall in late October or early November when they begin actively growing again. They can also be fertilized in the springtime just before flowers emerge to give them a boost for flower production. Use slow-release granular or liquid fertilizers. You can also try organic options such as compost or worm castings to help improve the soil.
Cut faded flower blooms off where the stalk emerges from the foliage to prevent seedpod formation and to conserve energy for future flowers.
Louisiana Super Plants is the AgCenter’s educational program that promotes university-tested, industry-approved plants. For more information on the initiative and a list of previously announced Super Plants, visit www.lsuagcenter.com/superplants.
Agcenter Horticulturist Heather Kirk-Ballard
Cut faded flower blooms off where the stalk emerges from the foliage to prevent seedpod formation and to conserve energy for future flowers.
Louisiana Super Plants is the AgCenter’s educational program that promotes university-tested, industry-approved plants. For more information on the initiative and a list of previously announced Super Plants, visit www.lsuagcenter.com/superplants.
Agcenter Horticulturist Heather Kirk-Ballard
It just doesn't get any easier than this, for you to have a big, bountiful beds of Louisiana Irises
Louisiana Irises are a hardy, disease/pest resistant and an easy to grow, magnificent showy flowers
Let's get planting
Louisiana Irises are a hardy, disease/pest resistant and an easy to grow, magnificent showy flowers
Let's get planting
Native irises carry Louisiana name worldwide
Louisiana iris is the name for a unique group of native iris species and their hybrids.
Blooming from late March to early May, the Louisiana iris is a floral ambassador that has carried our state’s name all over the world.
Louisiana iris is the name used worldwide for a unique group of native iris species and their hybrids. Their extraordinary beauty and reliability in the garden have made them increasingly popular, but they still deserve more recognition and use here in their home territory. The Louisiana iris is our state’s official wildflower.
Though a number of iris species are native to Louisiana, only five species – Iris brevicaulis, Iris fulva, Iris giganticaerulea, Iris hexagona and Iris nelsonii – are known as “The Louisianans.”
Only in south Louisiana do all five species occur together. They are closely related and will interbreed with each other but with no other species. The crossing, or interbreeding, of these species has resulted in the modern hybrid varieties we grow today. Their large, attractive flowers cover a broad range of colors, including many shades of blue, purple, red, yellow, pink, gold, brown, lavender, burgundy and white.
Be sure to not confuse Louisiana irises with the yellow and blue flag irises. Louisiana irises are much better performers.
The best time to plant Louisiana irises is in August and September when they are dormant, but you can buy and plant them as well while they are in bloom in spring with good success. When purchased and planted in spring, however, Louisiana irises need to be handled carefully to avoid damaging the foliage and flower buds. And you may need to stake the plants to hold them upright after planting. But once they’re established, Louisiana irises don’t need staking.
Louisiana irises should be grown with as much direct sun as possible. Although they will tolerate shade for part of the day, at least six hours of direct sun are needed for good blooming. You can plant Louisiana irises in beds by themselves, combined with other perennials or even in aquatic gardens.
When preparing a spot to plant them in a typical bed, incorporate a generous 3-inch layer of compost, rotted manure or peat moss and some all-purpose fertilizer into the soil. These irises grow best in a soil high in fertility and organic matter.
Aquatic culture is one of the easiest and most natural ways to grow Louisiana irises – and the foliage tends to stay more attractive during the summer. Simply place a potted iris into your decorative pond or aquatic garden so the rim of the pot is a few inches below the water’s surface. These plants also grow well and look great planted in the ground on the edges of large ponds. They also are excellent plants for rain gardens.
The large seedpods that form after flowering should be removed as soon as you notice them to keep the plants more attractive and vigorous. Next fall, in October or November, fertilize the irises as they begin their winter growing season.
Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.lsuagcenter.com/lahouse and www.lsuagcenter.com/lyn.
Rick Bogren
Louisiana iris is the name for a unique group of native iris species and their hybrids.
Blooming from late March to early May, the Louisiana iris is a floral ambassador that has carried our state’s name all over the world.
Louisiana iris is the name used worldwide for a unique group of native iris species and their hybrids. Their extraordinary beauty and reliability in the garden have made them increasingly popular, but they still deserve more recognition and use here in their home territory. The Louisiana iris is our state’s official wildflower.
Though a number of iris species are native to Louisiana, only five species – Iris brevicaulis, Iris fulva, Iris giganticaerulea, Iris hexagona and Iris nelsonii – are known as “The Louisianans.”
Only in south Louisiana do all five species occur together. They are closely related and will interbreed with each other but with no other species. The crossing, or interbreeding, of these species has resulted in the modern hybrid varieties we grow today. Their large, attractive flowers cover a broad range of colors, including many shades of blue, purple, red, yellow, pink, gold, brown, lavender, burgundy and white.
Be sure to not confuse Louisiana irises with the yellow and blue flag irises. Louisiana irises are much better performers.
The best time to plant Louisiana irises is in August and September when they are dormant, but you can buy and plant them as well while they are in bloom in spring with good success. When purchased and planted in spring, however, Louisiana irises need to be handled carefully to avoid damaging the foliage and flower buds. And you may need to stake the plants to hold them upright after planting. But once they’re established, Louisiana irises don’t need staking.
Louisiana irises should be grown with as much direct sun as possible. Although they will tolerate shade for part of the day, at least six hours of direct sun are needed for good blooming. You can plant Louisiana irises in beds by themselves, combined with other perennials or even in aquatic gardens.
When preparing a spot to plant them in a typical bed, incorporate a generous 3-inch layer of compost, rotted manure or peat moss and some all-purpose fertilizer into the soil. These irises grow best in a soil high in fertility and organic matter.
Aquatic culture is one of the easiest and most natural ways to grow Louisiana irises – and the foliage tends to stay more attractive during the summer. Simply place a potted iris into your decorative pond or aquatic garden so the rim of the pot is a few inches below the water’s surface. These plants also grow well and look great planted in the ground on the edges of large ponds. They also are excellent plants for rain gardens.
The large seedpods that form after flowering should be removed as soon as you notice them to keep the plants more attractive and vigorous. Next fall, in October or November, fertilize the irises as they begin their winter growing season.
Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.lsuagcenter.com/lahouse and www.lsuagcenter.com/lyn.
Rick Bogren
LOUISIANA IRISES
by Allan Williams from the LSU AgCenter publications
GROWING LOUISIANA IRISES
Louisiana irises can be grown successfully throughout Louisiana and in much of the United States.
Although the original species often grow in swampy or boggy conditions in their native habitats, the species and hybrids also can be grown in ordinary garden beds with excellent results.
The iris lover can expect outstanding results when they grow Louisiana irises in containers in aquatic gardens or planted in the ground at the edge of ponds.
They can be planted around a house, fence line or practically anywhere bedspace is desired.
Their culture is really quite easy as long as you provide the right growing conditions and take advantage of their growing seasons for flower production and their dormant season for propagation. Remember you are developing your irises for beautiful flower display during their growing season and you are expanding the growing area and numbers of irises during their dormant season. So Louisiana irises are on the move to give the iris lover continuous opportunities to develop more and more of the flowers for which they are so loved.
It is important to know that the active growing season for Louisiana irises is different from most herbaceous perennials that are typically dormant in winter.
Louisiana irises begin to grow as the weather cools down in October and continue to grow until April when they bloom.
After all the flowers on a stalk have bloomed, cut the flower stalk off where it emerges from the foliage. Cutting here prevents seed pod formation. Making seeds is a wasted effort unless you are breeding Louisiana irises.
The energy put into making seeds is better put into strong rhizome growth and future flowers.
In addition, the heavy seed pods pull the plant over causing it to flop unattractively.
By June, the irises go dormant, and some or most of the foliage turns yellow and brown.
During summer dormancy, feel free to trim off the yellow/brown foliage to make the planting more attractive.
Irises are usually at their most dormant (although some green foliage may remain) in August and September.
Those that receive abundant moisture and those growing in aquatic situations generally do not go as dormant as those in drier conditions, and more of the foliage stays green through the summer.
And this dormant season is THE time to identify the clusters of rhizome growth and is the opportune time to separate the rhizomes to be replanted in expanded beds or given away to admiring neighbors.
Location
Louisiana irises are also strikingly beautiful planted on the edges of ponds, creeks or streams.
The sight of blooming Louisiana irises reflected in water is one of spring’s great pleasures.
Bed Preparation
Louisiana irises prefer an acid soil with a pH of 6.5 or somewhat lower.
However, they are adaptable and will also grow well in soils that are slightly alkaline.
A soil high in fertility and rich in organic matter will encourage vigorous growth and abundant flowers.
The first step of bed preparation is to remove any unwanted vegetation from the area and then turn the soil to a depth of about 8 inches.
Sandy soils that tend to dry out rapidly should be amended with 4 inches of organic matter.
Clay soils are fine for Louisiana irises, but will be improved by the addition of 2-4 inches of organic matter.
Next, sprinkle a light application of a general purpose fertilizer over the area following package directions, and thoroughly incorporate the organic matter and fertilizer into the soil.
by Allan Williams from the LSU AgCenter publications
GROWING LOUISIANA IRISES
Louisiana irises can be grown successfully throughout Louisiana and in much of the United States.
Although the original species often grow in swampy or boggy conditions in their native habitats, the species and hybrids also can be grown in ordinary garden beds with excellent results.
The iris lover can expect outstanding results when they grow Louisiana irises in containers in aquatic gardens or planted in the ground at the edge of ponds.
They can be planted around a house, fence line or practically anywhere bedspace is desired.
Their culture is really quite easy as long as you provide the right growing conditions and take advantage of their growing seasons for flower production and their dormant season for propagation. Remember you are developing your irises for beautiful flower display during their growing season and you are expanding the growing area and numbers of irises during their dormant season. So Louisiana irises are on the move to give the iris lover continuous opportunities to develop more and more of the flowers for which they are so loved.
It is important to know that the active growing season for Louisiana irises is different from most herbaceous perennials that are typically dormant in winter.
Louisiana irises begin to grow as the weather cools down in October and continue to grow until April when they bloom.
After all the flowers on a stalk have bloomed, cut the flower stalk off where it emerges from the foliage. Cutting here prevents seed pod formation. Making seeds is a wasted effort unless you are breeding Louisiana irises.
The energy put into making seeds is better put into strong rhizome growth and future flowers.
In addition, the heavy seed pods pull the plant over causing it to flop unattractively.
By June, the irises go dormant, and some or most of the foliage turns yellow and brown.
During summer dormancy, feel free to trim off the yellow/brown foliage to make the planting more attractive.
Irises are usually at their most dormant (although some green foliage may remain) in August and September.
Those that receive abundant moisture and those growing in aquatic situations generally do not go as dormant as those in drier conditions, and more of the foliage stays green through the summer.
And this dormant season is THE time to identify the clusters of rhizome growth and is the opportune time to separate the rhizomes to be replanted in expanded beds or given away to admiring neighbors.
Location
Louisiana irises are also strikingly beautiful planted on the edges of ponds, creeks or streams.
The sight of blooming Louisiana irises reflected in water is one of spring’s great pleasures.
Bed Preparation
Louisiana irises prefer an acid soil with a pH of 6.5 or somewhat lower.
However, they are adaptable and will also grow well in soils that are slightly alkaline.
A soil high in fertility and rich in organic matter will encourage vigorous growth and abundant flowers.
The first step of bed preparation is to remove any unwanted vegetation from the area and then turn the soil to a depth of about 8 inches.
Sandy soils that tend to dry out rapidly should be amended with 4 inches of organic matter.
Clay soils are fine for Louisiana irises, but will be improved by the addition of 2-4 inches of organic matter.
Next, sprinkle a light application of a general purpose fertilizer over the area following package directions, and thoroughly incorporate the organic matter and fertilizer into the soil.