Types of iris

Style (of color pattern)

American Iris Society Awards

When to Plant

For best results, Iris should be planted in July, August or September. It's imperative that the roots of newly planted Iris be well-established before the growing season ends. In areas with hot summers and mild winters, September or October planting may be preferred.

Where to Plant

Iris need at least a half day of sun. In extremely hot climates some shade is beneficial, but in most climates Iris do best in full sun. Be sure to provide your Iris good drainage, planting either on a slope or in raised beds.

Soil Preparation

Iris will thrive in most well-drained garden soils. Planting on a slope or in raised beds helps ensure good drainage. If your soil is heavy, coarse sand or humus may be added to improve drainage. Gypsum is an excellent soil conditioner that can improve most clay soils. The ideal pH is 6.8 (slightly acidic), but Iris are tolerant in this regard. To adjust the pH of your soil, lime may be added to acidic soils or sulfur to alkaline soils. It is always best to have your soil analyzed before taking corrective measures.

Depth to Plant

Iris should be planted so the tops of the rhizomes are exposed and the roots are spread out facing downward in the soil. In very light soils or in extremely hot climates, covering the rhizome with 1 inch of soil may be desirable. Firm the soil around each rhizome and then water to help settle the soil. A common mistake is to plant Iris too deeply.

Distance Apart

Iris are generally planted 12 to 24 inches apart. Close planting gives an immediate effect, but closely planted Iris will need to be thinned often. Plants spaced further apart will need less frequent thinning.

Watering

Newly set plants need moisture to help their root systems become established. Specific watering information depends on your climate and your soil, but keep in mind that deep watering at long intervals is better than more frequent shallow waterings. Once established, Iris normally don't need to be watered except in arid areas. Overwatering is a common error.

Fertilization

Specific fertilizer recommendations depend on your soil type, but bone meal, superphosphate and 6-10-10 are all effective. A light application in the early spring and a second light application about a month after bloom will reward you with good growth and bloom. Avoid using anything high in nitrogen, as nitrogen encourages rot problems.

Thinning Old Clumps

Iris need to be thinned or divided before they become overcrowded, generally every 3-4 years. If Iris are allowed to become too crowded the bloom will suffer, some varieties may crowd others out and disease problems may be aggravated. Old clumps may be thinned by removing the old divisions at the centers of the clumps and leaving new growth in the ground. Or, you may dig up the entire clump and remove and replant the large new rhizomes.

General Garden Care

Keep your Iris beds clean and free of weeds and debris, allowing the tops of the rhizomes to bask in the sun. Bloom stems should be cut off close to the ground after blooming. Healthy green leaves should be left undisturbed, but diseased or brown leaves should be removed.

Iris Versicolor

Botanical: Iris Versicolor (LINN.)
Family: N.O. Iridaceae

• Description
• Constituents
• Medicinal Action and Uses

---Synonyms---Blue Flag. Poison Flag. Flag Lily. Liver Lily. Snake Lily. Dragon Flower. Dagger Flower. Water Flag.
---Part Used---Root.

Iris Versicolor (Linn.) is a perennial herb, found abundantly in swamps and low grounds throughout eastern and central North America, common in Canada, as well as in the United States, liking a loamy or peaty soil. It is not a native of Europe.

It grows 2 to 3 feet high, with narrow, sword-shaped leaves, and from May to July produces large, handsome flowers, blue, except for the yellow and whitish markings at the base of the sepals.

---Description---Blue Flag Rhizome has annual joints, 2 or more inches long, about 3/4 inch in diameter, cylindrical in the lower half, becoming compressed towards the crown, where the cup-shaped stem-scar is seen, when dry, and numerous rings, formed of leaf scars are apparent above and scars of rootlets below. It is dark brown externally and longitudinally wrinkled. The fracture is short, purplish, the vascular bundles scattered through the central column. The rootlets are long, slender and simple. The rhizome has a very slight but peculiar odour, and a pungent, acrid and nauseous taste.

Owing to the similarity of name, and the appearance before blooming, this flag is sometimes mistaken by American children for Sweet Flag or Calamus, which grows in the same localities, often with disastrous results.

Of the 100 species of true Iris, twenty-two inhabit the United States, but only one, Iris Missouriensis, much resembles this species (the rhizome of which yields an official American drug), or has a rhizome likely to be mistaken for it.

When cultivated, the American Blue Flag succeeds best in heavy, rich, moist soil. If planted in August or September, it can be harvested at the end of October the following year. The yield per acre is 3 to 4 tons of the rhizome.

---Constituents---The rhizome contains starch, gum, tannin, volatile oil, 25 per cent of acrid, resinous matter, isophthalic acid, traces of salicylic acid and possibly an alkaloid, though a number of substances contained are still unidentified. It owes its medicinal virtues to an oleoresin.

Distilled with water, the fresh rhizome yields an opalescent distillate, from which is separated a white, camphoraceous substance with a faint odour. The oil possesses the taste and smell, but only partly the medicinal activity of the drug.

---Medicinal Action and Uses---The root is an official drug of the United States Pharmacopoeia and is the source of the Iridin or Irisin of commerce, a powdered extractive, bitter, nauseous and acrid, with diuretic and aperient properties.

Iridin acts powerfully on the liver, but, from its milder action on the bowels, is preferable to podophyllin.

The fresh Iris is quite acrid and if employed internally produces nausea, vomiting, purging and colicky pains. The dried root is less acrid and is employed as an emetic, diuretic and cathartic. The oleoresin in the root is purgative to the liver, and useful in bilious sickness in small doses.

It is chiefly used for its alterative properties, being a useful purgative in disorders of the liver and duodenum, and is an ingredient of many compounds for purifying the blood. It acts as a stimulant to the liver and intestinal glands and is used in constipation and biliousness, and is believed by some to be a hepatic stimulant second only to podophyllin, but if given in full doses it may occasion considerable nausea and severe prostration.

Its chief use is for syphilis and some forms of low-grade scrofula and skin affection. It is also valuable in dropsy.

It is said to have been used by the southern North American Indians as a cathartic and emetic.

Iris USAGE

There are hundreds of species and cultivars of iris in all colors of the rainbow. Iris vary from tiny woodland groundcovers to dramatic flowers for the sunny border to species that thrive in swampy soil. There is an iris that will do well in virtually every garden.

HEIGHT/SPREAD

The many different species vary from low ground covers such as Iris cristata at only 6 inches tall to some of the large Japanese iris at 3 to 4 feet tall. Bearded iris ranges from about 6 inches in the miniatures to more than 3 feet in the large types.

GROWTH RATE

Iris are dependable, long-lived perennials. Their growth rate varies by species and type.

ORNAMENTAL FEATURES

Iris are grown for their graceful flowers in an endless array of brilliant colors. The bold sword shaped foliage is also an excellent contrast to the more mounded forms of many garden plants.

PROBLEMS

Poor flowering is normally due to planting in excessive shade, using too much fertilizer, planting the rhizomes too deep, or plants that have become too crowded and need dividing.

Bacterial soft rot is the most serious iris disease. Soft rot causes the rhizomes to become mushy and have a disagreeable odor. Remove any yellowing leaves promptly to help prevent spread of the disease. Iris leaf spot, caused by a fungus, is the most common disease. Remove all leaf and other debris in fall, since diseases and insects often overwinter on old foliage.

Iris borer is the most serious insect pest of iris. Bacterial soft rot readily attacks borer-infested plants. Aphids can be a nuisance problem at times.

LANDSCAPE USE

Most iris, especially bearded iris, will grow best with full sun for at least 6 to 8 hours a day. In very hot areas though, some shade in the afternoon will help keep flower colors from fading in the heat. Iris should be planted in an area with good air circulation to help prevent disease problems.

Most iris need very well-drained soil. Japanese and Louisiana iris will grow in wet soil. If your soil is not ideal you can amend it with organic matter and build raised beds for better drainage. Do not use manure unless it is very well-composted (aged for at least one year). Manure can encourage iris sof t rot. Bearded iris prefer slightly alkaline soil. Many of the beardless iris like a more acid soil. It is a good idea to test your soil and amend the soil before planting a new iris bed.

Fertilize a new iris bed when preparing the soil before planting with a complete fertilizer low in nitrogen and high in phosphorus and potassium. Follow soil test recommendations for best results. In the absence of test results apply 1 pound of 5-10-10 per 100 square feet. Work the fertilizer into the soil and let the bed settle before planting.

When feeding established iris, do not let fertilizer touch the rhizomes. It is better to underfeed than to overfeed bearded iris. Reblooming varieties, however, are more likely to rebloom with supplemental food and water after spring bloom.

Remove old blooms and stalks promptly after flowering to allow the plant to devote its energy to growth rather than seed. Removing old blooms and stalks also encourages repeat flowering on reblooming iris.

The best time to plant bearded iris is July through September, or October near the coast. This will allow them to become well-established before winter. Japanese, Louisiana and Siberian iris can be transplanted during the summer and early fall. Container-grown iris can be planted in the spring.

Bearded iris are grown from a fleshy, bulblike stem called a rhizome that grows horizontally just below the soil surface. Plant iris with the rhizome high in the soil, and the roots well-anchored. Dig two trenches with a ridge between them, place the rhizome on the ridge and spread the roots carefully in the trenches. Then fill the trenches with soil, letting the top surface of the rhizome be just barely beneath the surface of the soil. In heavy clay soils the rhizome should be planted higher so that up to half of the rhizome is exposed above soil level. Firm the soil well and water thoroughly.

After three to five years, iris generally become crowded and should be divided.

TYPES, SPECIES AND CULTIVARS

The iris most often grown fall into two main groups: Bearded iris and Beardless iris.

Miniature Dwarf Bearded These are the tiniest bearded iris, with stems from 2 inches to 8 inches tall. They are also the earliest to bloom. They are grown in rock gardens or planted in low drifts at the front of the flowerbed.

Standard Dwarf Bearded These iris range in height from 8 inches to 15 inches. They bloom early in the iris season.

Intermediate Bearded These iris stand from 16 inches to 28 inches high. They are large enough that their individual stalks may be nicely branched, forming an elegant bouquet.

Border Bearded These are in the same height range and bloom size as the intermediates, but blooming later with the tall beardeds.

Miniature Tall Bearded These iris have blooms that are smaller than on a border bearded on thin and wiry stems. They are well-suited for arrangements.

Tall Bearded These have stalks over 28 inches tall, extending to approximately 40 inches in height. Each individual stalk makes a stately arrangement in the garden or in a vase. Tall bearded iris have ruffled edged petals or other embellishments more often than other groups of iris. Tall beardeds are the most popular and commonly grown iris type. There are thousands of cultivars of tall bearded iris. In the South, we can grow a number of cultivars that bloom in the spring and then rebloom in late summer or fall.

Reblooming Tall Bearded Iris

White Flag Iris (Iris albicans) This historic iris was once very common throughout the South. It has off-white flowers that bloom in March above gray-green leaves. This old iris is heat-tolerant and durable.

Florentine Iris (Iris germanica ‘Florentine’) This is a very old cutivar that has been grown for centuries for its scented rhizome, used in perfumery. The flowers are a very pale grey-blue, almost white. It blooms in April.

Dalmation Iris (Iris pallida) This historic iris is well adapted to growing in the South. It typically has pale blue flowers above gray leaves and blooms in late April. There is a beautiful variety with yellow striped leaves.

Beardless Iris:

These types of iris have different growing needs than bearded iris. Siberians will tolerate light shade but Japanese and Louisiana Iris need full sun. Louisiana and Japanese iris require moist conditions during the summer months. All are moderate to heavy feeders and need to be fertilized regularly. Most do best in somewhat acid soil, between pH 5.5 and 6.5

Siberian Iris These are excellent landscape plants, easy to grow, with elegant vertical blue-green foliage that looks good throughout the growing season. The blooms are mostly blue, violet and white with large falls and smaller standards. They grow to a height of 2 to 4 feet. Siberian iris thrive in moist soil, but do not like standing water. They will also tolerate most ordinary garden soil and are among the easiest iris to grow in most regions.

Japanese Iris (I. ensata) These require a slightly acid soil and have the most spectacular flowers of all the iris. Blooms are usually huge, ruffled and flat in form; some are marbled with gray or white. They bloom about a month after tall beardeds. Japanese iris will flourish in wet environments, even in shallow water. These iris are heavy feeders and require lots of organic matter for nutrients. They need six hours of full sun.

Louisiana Iris These iris are native to the Gulf Coast. The blooms are very wide-petaled and brightly colored. Louisiana iris need at least a half day of sun, a neutral or acidic soil, and plenty of fertilizer and water. Sandy or heavy clay soils should be amended with organic matter. New growth appears in fall, and in mild winters the foliage remains erect and green.

Louisiana iris rhizomes should be planted deeper than other iris, at least 1 inch under the soil, then mulched with 2 to 4 inches of compost..

Dwarf Crested Iris (Iris cristata) This small native iris thrives in lightly shaded gardens.  Light blue flowers in early spring with attractive miniature foliage throughout the growing season.  Plant the rhizome at ground level rather than burying in the soil.  Prefers infertile, well-drained soil.  

Yellow Flag Iris (Iris pseudacorus) Moisture-loving vigorous iris grows 4 to 5 feet tall with butter-yellow flowers. Although it tolerates well-drained areas, it is happiest in 3 to 6 inches of water or areas that stand in water periodically.

Blue Flag Iris (Iris versicolor) Blue flag is a beautiful native iris that grows in damp areas in the eastern United States. Lavender-blue flowers on 3-foot stems during May and June.

Dutch Iris These slender, graceful flowers are grown from bulbs. Dutch iris bloom in early summer in deep and light blue, purple, yellow and white on 24 inch tall stems. They prefer sun or afternoon shade and rich, well-drained soil. Plant bulbs 4 to 6 inches deep in October or November.

Siberian Iris

Siberian Irises are ideal for most gardens, as they have many characteristics suitable to today's sustainable urban landscape practices. They are extremely hardy and require minimal maintenance. They provide drought and moisture tolerance, pest and disease resistance, shade tolerance, soil adaptability, and are not invasive. Their spring flowers flutter like dancing butterflies above grass-like foliage. And they offer variety in height, texture, form, and seasonal interest. These traits make Siberians ideal for private and public gardens in formal or natural settings. Not your grandmother's bearded iris Siberians are beardless irises differentiated from the common bearded iris by more than the lack of a beard in the fall.

The Siberian Iris species are meadow plants and prefer the abundant moisture found in spring meadows and streams. In contrast, common bearded irises are steppe plants and thrive in sunny, dry conditions where their rhizomes are baked. The moisture loved by Siberian Irises will rot their bearded cousins. Siberian species thrive in meadows in constant competition with grasses and forbs, so they are great for natural perennial borders.

There are more than 1,000 modern hybrids mostly derived from two species: I. sibirica, which is found throughout Central Europe into Russia, and I. sanguinea, which is found in Japan, Korea, northeast Asia, and Siberia. I. typhifolia, a recently rediscovered iris from northeast China, completes the "robust" class of Siberian Iris. Also known as the "garden Siberians," they are genetically differentiated by having a chromosome count of 2n=28. A second group of eight species found in the highlands of southwest China into the Himalayas comprises a "gracile" sub classification. Also known as the Sino-Siberians, they have a chromosome count of 2n=40. Because the climate of their tropical highland meadows lacks the temperature extremes of Minnesota, species and hybrids from this class are more difficult to maintain in our region. Siberian Iris culture These irises like full sun. They can tolerate some shade, but less than a half-day of sun will reduce bloom and vigor. While Siberians also tolerate a wide range of soils, they favor neutral to slightly acidic conditions-pH 5.5 to 6.5-and will languish or dwindle in alkaline soil. They also prefer soil with ample organic matter; thoroughly composted manure, peat moss, and other organic materials make excellent soil amendments.

All Siberian Irises like abundant water during the growing season; 1 inch of water per week is recommended. They can withstand flooding for short periods of time, yet they are not water irises, and a site should have adequate soil drainage. Established garden Siberians can tolerate dry conditions later in the season (around the time that their native meadows would often dry out). Planting Prepare bare-root stock by soaking the roots for several hours before planting. Plant Siberians with the base of the leaf system or crown roughly 1 to 2 inches below the final level of soil, and make sure no, air pockets remain around the root system.

Thoroughly water the iris at the time of planting and for the first couple of months after planting, not allowing the plant to become dry. Traditionally, early fall is the best time for planting bare-root material as it gives roots and rhizomes a chance to anchor before winter. In our northern climate spring planting also can be successful. Transplanting with a root ball of soil avoids transplant shock. Spring-planted Siberians may be expected to flower the following year. Fall-planted irises cannot be expected to flower until the second year. To maintain abundant bloom and vigorous growth you can transplant Siberians every six to nine years. Divide clumps with a fork or spade, and remove old roots and rhizomes from the center. Transplant the outer portions as you would new plants. Siberian Irises are moderate feeders.

A minimum program of a balanced 10-10-10 granular fertilizer may be applied as new growth appears, just after bloom, and once in early fall. Fertilizer should not be applied to new plantings for a month. Some growers apply soluble fertilizer twice in early spring-once before bloom, after bloom, and in early fall. New plantings should be mulched the first year to moderate soil temperatures while the root and rhizomes expand. A winter mulch prevents heave from the freeze and thaw cycle. Well-established plantings may only need mulching for weed control; pine needles, shredded leaves, wood chips, pine bark, cocoa bean hulls, straw, and peat moss are excellent choices. Unwanted seedpods may be removed so the plant will return energy to root and rhizome growth. Foliage can be cut and removed in the fall after turning brown. By doing so, you remove sources for future pest, fungus, and disease contamination.

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