When to prune irises?


The diverse iris genus contains more than 200 distinct species and countless cultivars. Iris is the goddess of the rainbow, and you can find iris blooms in pink, blue, lilac, purple to brown, yellow, orange, almost black, and white. There are no true reds. Many types of iris have fine foliage, whether short or tall, which is a good thing, because the flowers have only a brief period of bloom. These perennials return reliably year after year. Irises usually have basal leaves in two ranks — linear to sword-shaped — often resembling a fan, arising from a thick rootstock (or rhizome), from fibrous roots, or, in some species, from a flower bulb.

How to grow: Most irises need full sun. Except for those like the water flag (Iris pseudacorus), which delights in a watery spot, or the Japanese iris (I. ensata), which thrives in humus-rich moist soil, most irises also prefer a good well-drained garden soil. If plants are protected from iris borers, they become permanently established in the garden.


Propagation: By division after flowering or in the fall or from seed.

Uses: Even though the bloom period is short, a bed of irises is ideal for a flower garden. There are also irises for the poolside and the pool, the wild or woodland garden, the early spring bulb bed, the cutting garden, and the rock garden.

Related species: Iris germanica (tall bearded iris), hardy from Zones 4-8, usually comes to mind when people think of irises. The flowers come in a multitude of color combinations and sizes, with hundreds of new varieties introduced every year. This iris is usually spring blooming, but some rebloom in fall. I. cristata (crested iris), hardy in Zones 5-8, prefers partial shade and a humus-rich soil and blooms in early spring. It is lavender-blue with a two-inch yellow crest across a six-inch stem. I. ensata (Japanese iris) is hardy in Zones 6-8. Richly colored blossoms are often more than six inches wide on stiff, tall stems, blooming in June. The blue flag, I. versicolor, is a lovely three-foot wildflower from the Northeast that appears in ditches and boggy areas along country roads. It is a great pond plant. I.I. sibirica (Siberian iris), hardy in Zones 4-8, has large flat lovely 3- to 4-inch flowers on 30-inch stems and great foliage-the swordlike leaves stand erect and eventually form a large clump. I. pseudacorus (yellow flag) is also a beautiful plant for a bog or at the edge of a pond or pool. The flowers, blooming from May to June, are yellow on 40-inch stems. It is beautiful but can be invasive.

Scientific name: Iris species

Want more information? Try these:

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  • Annual Flowers. Complement your perennials with these great annual flowers. We’ve organized them by color, sunlight, soil type, and height to make it easy to plan your garden.

Planting and Growing Bearded Iris

Flamboyant blooms on stately, splendid plants grace the garden in June. Bearded Irises are available in a veritable rainbow of colors, from vibrant primaries, to subtle bicolors and gentle pastels. Breeders have introduced a variety of reblooming Irises, which have a tendency to flower again from late summer into fall depending on climate and growing conditions. Please note that Bearded Irises may not bloom the first year after planting.

Light/Watering: Full sun and well-drained soil are important for vigorous growth and flowering. Do not overwater, as too much moisture in the soil can cause the rhizomes (roots) to rot, but do water deeply during summer drought. Consistent watering is especially important for reblooming Irises.

Fertilizer/Soil and pH: Iris will not tolerate soils that are wet in winter. Good drainage is important all year, and a pH near neutral (7.0) is preferred. In climates with very hot summers, plant the rhizome just below the soil surface; in cooler climates, the top of the rhizome should be exposed. Do not mulch around the rhizome as this practice may encourage rot. Fertilize in early spring with an all-purpose fertilizer scratched in around the plants, avoiding direct contact with the rhizome. Reblooming Irises perform best if fertilized again after the first wave of flowering is finished.

Pests/Diseases: The Iris borer, the worst pest of these lovely plants, overwinters as eggs in spent leaves, so don’t give the critters a hiding place. The borers emerge in the spring as tiny caterpillars, which spend a couple of weeks boring through the leaves down into the rhizome, where they grow fat and cause great damage, often leading to soft rot that causes even more damage. Vigilance can help—it’s actually possible to kill the borers in situ if you catch them early enough. You’ll see vertical streaks in the leaves; that’s your guide to help you squash the pests. If you see any signs of rot in the rhizome, dig it up and remove the affected parts. Unless the infestation is severe, plants usually recover, or grow lustily enough that you can salvage healthy chunks to keep growing. The rhizomes may also become infected with soft rot. Well-drained soils are important, so add sand if your soil is heavy and plant so that the top of the rhizome is above the soil line. If soft rot does occur, dig out and discard affected rhizomes and cut away any smaller areas of damage.

Companions: Irises are at their best in the company of other perennials, especially Lilies, Herbaceous Peonies, Roses, and Oriental Poppies. Be careful to leave enough room between plants to provide for good air circulation.

Reflowering: Remove spent blooms consistently; Bearded Irises will flower sequentially on buds spaced along the stems. After blooming is finished, cut flower stems down at their base. Although reblooming varieties have a tendency to rebloom, sending up new fans that sport flower spikes as they mature later in the season, they are not guaranteed to bloom a second time. Repeat bloom is dependent on many things, including geographic location and growing conditions.

Dividing/Transplanting: Divide your Irises when the clump becomes crowded and bloom diminishes, usually every 3 to 4 years. The timing of division is very different than that of most perennials, because Bearded Irises go dormant shortly after flowering, and summer is the ideal time to dig up the rhizomes. Even though reblooming Irises don’t go dormant, this is also the correct time to divide those varieties. Break the rhizomes into pieces or cut them with a sharp knife. Select divisions with healthy fans of leaves, most likely from the outermost part of the plant. Discard the crowded interior pieces, and any that show signs of soft rot; dispose of these in the trash, not in the compost. This is the time to trim the leaves back to about 6 inches in length. Some gardeners like to dust the cut surfaces with powdered sulfur, or to dunk rhizomes in a solution of 1 part bleach to 10 parts water. We haven’t found this step necessary, but it might be advisable if you have had problems with rot. Replant promptly. You will probably find yourself with extra divisions you can share with friends.

End-of-Season Care: After hard frost in the fall, cut foliage back hard, remove any foliage that appears spotted or yellowed and dispose of all debris in the trash. We recommend winter protection in cold climates, especially for the first winter after planting. We suggest covering the rhizomes with an inch or two of sand topped with a light layer of evergreen boughs, applied after the ground freezes and removed when the Forsythias bloom the following spring.

Calendar of Care

Early Spring: Diligently remove and destroy any old foliage to allow for fresh, new growth and prevent Iris borers from emerging as the weather warms. Remove any winter mulch. Feed plants with an all-purpose fertilizer scratched in around the plants, avoiding direct contact with the rhizome.

Mid-Spring: Watch vigilantly for the telltale signs of Iris borers in the foliage — dark vertical lines that may appear watery show up in the leaves. Squash the bugs where they live; if infestation is severe, remove affected foliage completely and destroy.

Late Spring: Taller forms may need staking. Deadhead as flowers fade, and cut entire flower spikes down at the base when blooming is finished. Fertilize reblooming varieties again after the first wave of flowering is through.

Summer: If plants need dividing, complete this task after flowering finishes and then trim the foliage back to six inches. Water divisions well during dry periods.

Fall: After hard frost in the fall, cut foliage back hard, remove any foliage that appears spotted or yellowed, and dispose of all debris in the trash. Winter protection in cold climates is recommended, especially for the first winter after planting. After the ground freezes, cover the rhizomes with an inch or two of sand topped with a light layer of evergreen boughs; remove when the Forsythias bloom the following spring.

allan becker*garden guru

As someone who loves blue flowers, I cannot find the appropriate words to describe the joy I experience when I see the blue variety of Dutch Irises in bloom. Nor can I begin to express how desolate I felt when I realized that this bulb will bloom for only two seasons here in USDA Zone 4.

Although this flower is just as important to my wife as it is to me – she used it as an accent flower in the pink-yellow-blue centerpieces for our wedding reception, many years ago – we are about to banish it from our flower beds.

The gardener, who strives to create an easy-care garden, has little interest in replanting the same spring flowering bulb each fall, or even every other fall. This hobbyist prefers to plant a bulb, knowing that the work is an investment that will reap dividends for several years to come. That is why I plant daffodils and narcissus, species tulips, crocus, and several varieties of the Darwin hybrid tulip. All seem to re bloom for many years, just like most perennials do.

If catalogs that sell spring flowering bulbs would inform us honestly that Dutch Irises need to be replaced regularly, perhaps fewer gardeners would consider buying them. I will no longer plant them because I consider them an unwise investment and a waste of precious time and energy.

One of the joys of gardening is the thrill of what will bloom next. Anticipating the experience of seeing a spring flowering bulb in bloom and then realizing that it has withered underground forever, is not what enjoyable gardening is all about.

The other day, I received an email from a client inquiring if I had actually planted the blue Dutch Irises she had asked for, over three years ago. She knows how eager I am to please my clients, and being certain that she did ask for them, was puzzled when they did not bloom this spring. Even I was puzzled, because I remember not only her request but also the time I spent planting them. After reading her message, I went into my garden to look for the ones that bloomed there last year. The spot where they once flowered so beautifully was now bare.

In the future, there will be no more blue Dutch Iris bulbs planted in my garden or that of my clients. If I want to enjoy this flower, I will visit the nearest florist shop where the supply is more reliable. There I will choose a bouquet of the taller variety, just like the ones my wife selected for our wedding centerpieces.

Peter Cundall: Summer means it’s time to rejuvenate irises

SUMMER has arrived at last. That means most gardens are relatively safe from frosts — although where we live in our frost-prone Tasmanian valley there is always a risk in early December.

At the moment I’m thankful for long hours of daylight because I’m spending so much time getting our garden organised for summer and autumn.

Actually, my first and most urgent job is bushfire safety. I’ve never seen such growth, with grass well over my head on the outskirts of our place and in our little orchard.

I’ll admit there’s a certain, almost sadistic pleasure in using a powerful brush cutter to scythe down this grass, right to the ground. I’d love to compost it immediately, of course — I’ve already made several big heaps — but it is still green, lush and amazingly heavy. So I leave it to dry off for a few days and then rake it up.

I’m also getting stuck into our roses. We have about 70 and right now they are blowing everyone’s mind. I’ve never seen such a perfect display. So far they are remarkably healthy with few showing signs of black spot disease.

That’s mainly because after a rain shower I dash out to shake all vulnerable, black-spot susceptible rose varieties. This stops rainwater from settling and ­remaining on the leaves.

Black spot fungus needs about seven hours of wet conditions before it can infect and penetrate a rose leaf.

So the quicker they dry, the less chance there is of black spot striking.

This is also why I was rather brutal when I pruned a few very congested roses. I took out at least half the branches, especially those growing into the centres of bushes

Opening up rose bushes to create wide gaps between branches allows good, leaf-drying air circulation. So far, black spot hasn’t had a chance to become a serious problem.

Later, in January, I’ll just use drip irrigation around our roses so the foliage can’t get wet.

I’m also getting stuck into some old-established bearded iris clumps. They urgently need dividing. As fast as they finish blooming, all dead heads are cut off and entire clusters of rhizomes are lifted from the soil and blasted clean with a hose jet.

This is the perfect time to divide and rejuvenate bearded iris clumps. They look a bit like big skinny crabs when lifted. However, most dark rhizome material has been dead a long time. Only the bright green parts — called “increase”, formed at leaf bases, are alive and healthy.

So it’s a simple job to first slice all leaves back hard to short, stubby fans and then cut free each healthy green increase from the old dead rhizomes.

These new iris divisions are best planted immediately as the replacement roots are now forming. The best location for me — believe it or not — is among our glorious roses.

The rhizomes are simply pushed flat into the soil with roots spread as widely as possible. The top part of each rhizome must be left fully ­exposed to the sun and weather.

Roses and bearded irises are natural companions. Even relatively small gaps between bush roses can successfully grow lovely irises. Every ­November they happily poke through and bloom away, just as the first rose buds are starting to open. It’s a fantastic continuity of non-stop, colourful blooms that lasts for months.

I’ve also been dividing up some dahlia clumps that were lifted last May. They were stored undercover in moist sand in winter and early spring.

The clumps are beginning to send out healthy new shoots that indicate the points where individual tubers can be cut free — always just beneath the central, woody old stem.

Planting huge, undivided clumps of dahlia tubers year after year is a common blunder. Apart from producing increasingly inferior blooms, these ancient, constipated clusters ­attract more diseases and pests.

Planting individual dahlia tubers is the only way to go. Make sure each dahlia plant has a strong wooden stake alongside to support those top-heavy, fragile stems.

All they need is a sunny, well drained, sheltered spot and plenty of water in dry periods.

When you hear the word “iris,” do you see a big bearded beauty rising up above swordlike leaves? You’re thinking of the bearded iris (Iris germanica), a popular spring/summer garden star. The Siberian iris (I. sibirica), another flower entirely, is well worth your attention, too.

Easier to grow than I. germanica and needing very little care, I. sibirica has no beard but is beloved for its delicate flowers and soft, grasslike foliage.

The Siberian iris generally grows 2 to 4 feet tall; withstands wind, rain, and cold; and makes a lovely cut flower. Impressively, one mature plant can send out more than 20 stems of flowers at once, in a bloom season that lasts from late April to early summer. The Siberian iris quickly fills in spaces in a sunny border and works well at corners, too. Good companion plants are aquilegia, daisies, lupines, peonies, phlox, and pinks.

Best Conditions for Iris

The Siberian iris grows well in USDA Zones 2 to 9. In northern regions, grow it in full sun. It performs reasonably well in light shade where seasons are warm. In extremely hot southern climates, grow it in a shady location. Although it will tolerate dry periods, for best performance, plant it with perennials that you water well all summer long.

How to Plant Iris

Plant rhizomes with the crowns 1 inch below the soil level and cover them with soil—2 inches deep, if the soil is sandy. To avoid air pockets beneath the crown, make a small hill of soil in the center of the planting hole, place the rhizome on the hill with the roots spread around it, fill the hole with soil, and pack it tight. Keep evenly moist for 6 to 8 weeks after planting.

Photo: Anna bogush/

Ensure a Long Season

To have Siberian irises in bloom for the longest period of time, include both early and late varieties in your garden. Here are a few examples:

Early Bloomers:

  • ‘Bouquet’
  • ‘Indy’
  • ‘Pleasures of May’

Late Bloomers:

  • ‘King of Kings’
  • ‘Liberty Hills’

For Best Iris Blooms

Remove spent flowers after they bloom to keep seed heads from forming. In late fall, cut foliage to the ground and mulch well after the ground has frozen.

After a few years, when large clumps form, divide them to ensure continued bloom. Dig mature iris plants in the spring or early summer after they bloom or in the early fall, well before frost threatens. Loosen the soil carefully and pry the rhizomes loose with a rocking motion. Cut the rhizomes with a sharp knife, leaving each new piece with two fan divisions. Plant the divisions, cover with soil to a depth of 1 to 2 inches (as directed), and keep the new plants evenly moist for 6 to 8 weeks after planting.

Photo: Michael thaler/

The Top 12 Siberian Iris Varieties

  • Siberian irises come in a wide range of colors—purple, blue, pink, lavender, yellow, white, and bi- and tritones. In a poll, the Society for Siberian Irises (SSI) members put these varieties at the top of their list: ‘Roaring Jelly’
  • ‘Over in Gloryland’
  • ‘Jewelled Crown’
  • ‘Strawberry Fair’
  • ‘Coronation Anthem’
  • ‘Shaker’s Prayer’
  • ‘Lady Vanessa’
  • ‘Sultan’s Ruby’
  • ‘Lake Keuka’
  • ‘Mesa Pearl’
  • ‘Pink Haze’
  • ‘Somebody Loves Me’

Iris: What’s in a Name?

In Greek mythology, Iris is the name of the goddess of the rainbow. The iris bloom has been the symbol of monarchs and royal families throughout history. One of the earliest paintings of an iris is a fresco in King Minos’s palace on the Greek island of Crete. The palace dates from 2100 b.c.

The Bourbon kings of France, including Louis XIV, adapted the iris bloom on royal banners as the “fleur-de-lis.”

The iris is the state flower of Tennessee, and the fleur-de-lis is the emblem of the city of New Orleans, Louisiana.

Growing Siberian Irises in the Home Garden

There are approximately 200 species of Iris. Bearded irises are one of the most common perennials in the home garden. Though less popular than the bearded irises, Siberian irises (Iris sibirica) are excellent perennials. They are hardy, easy to grow, and relatively trouble-free.

Iris flowers are composed of 6 segments. The inner 3 upright segments are the true petals and are referred to as standards. The drooping, outer 3 segments are petal-like sepals and are known as falls.

The flowers of Siberian irises are smaller and more delicate than those of the bearded irises. Unlike bearded irises, their falls do not have fuzzy growths or beards. Numerous varieties of Siberian irises are available. They are available in shades of blue, purple, wine-red, pink, white, and yellow. Their flowers are borne atop tall stems in late May or June.

The foliage of Siberian irises is narrow (approximately 1/2 inch wide), upright, grass-like in appearance. The green foliage often turns to an attractive yellow or orange-brown in the fall. Siberian iris varieties range in height from 12 to 40 inches.

Siberian irises perform best in moist, well-drained, fertile soils. However, they will tolerate poor, dry sites. They can be grown in partial shade to full sun.

Siberian irises are usually planted in spring or late summer. However, container grown material can be planted any time during the growing season. Space plants about 18 to 24 inches apart. Plant 3, 5, or more of the same variety in a clump for the best visual display.

To aid establishment, water Siberian irises once a week during hot, dry weather. Water when needed for at least one full growing season.

Plants seldom bloom the first year after planting. Siberian irises should be blooming well by the third or fourth year. They will eventually form large, well-established clumps.

Established Siberian irises don’t require a great deal of care. Plants can be lightly fertilized in early spring with an all-purpose garden fertilizer, such as 10-10-10. They can also be fertilized immediately after bloom. A 2- to 3-inch-layer of mulch around the plants helps control weeds and conserves soil moisture. If possible, water once a week during hot, dry weather. Cut back the dead debris in late fall or early spring.

Siberian irises don’t have serious insect or disease problems. Unlike bearded irises, they are seldom bothered by the iris borer, soft rot, or leaf spot.

Division is rarely necessary for Siberian irises. Divide Siberian irises when clumps become crowded or when flowering decreases. Clumps can be divided in early spring at the first sign of growth or immediately after bloom.

Home gardeners can choose from numerous Siberian iris varieties. Suggested varieties include:

  • Butter and Sugar-white standards, yellow falls, 28 inches tall.
  • Caesar’s Brother-dark purple flowers, 36 inches.
  • Dreaming Yellow-cream standards, pale yellow falls, 30 inches.
  • Eric the Red-dark wine-red flowers, 36 inches.
  • Flight of Butterflies-violet-blue standards, white falls with butterfly-wing pattern of violet-blue veins, 36 inches.
  • Halcyon Seas-medium violet-blue flowers, 36 inches.
  • Jeweled Crown-deep wine-red flowers, falls have large circular gold blaze which fades to white, 24 inches.
  • King of Kings-large white flowers, 36 inches.
  • Lady Vanessa-light wine-red standards, ruffled medium wine-red falls, 36 inches.
  • Little White-white flowers, 12 to 18 inches.
  • Orville Fay-medium blue with darker blue veins, 36 inches.
  • Pink Haze-pink-lavender flowers, 38 inches.
  • Ruffled Velvet-violet standards, darker falls, 24 inches.
  • Savoir Faire-deep blue flowers, 36 inches.
  • Snow Queen-white flowers, 32 inches.
  • Sparkling Rose-rose-pink flowers, 30 inches.
  • Spring’s Brook-blue-violet flowers, 40 inches.
  • Sultan’s Ruby-deep magenta flowers, 30 inches.
  • Super Ego-light blue standards, lighter falls, 30 inches.
  • Wing on Wing-White ruffled flowers, 36 inches.

When selecting perennials for the home garden, be sure to include Siberian irises.

This article originally appeared in the March 28, 1997 issue, pp. 29-30.

A Guide to Growing Iris Blooms All Season

For those of us that love irises, their blooms seem to come and go much too quickly in the average garden. Most irises bloom for a week or two and then fade into the background of the garden for the rest of the season.

Irises in garden of Graeme Grosvernor, courtesy of the American Iris Society

This would be the end of the story for the iris if there were only one species of iris to grow. Lucky for us, there are actually several different species and cultivars of iris that bloom at different times throughout the season. Using a mix of different species and cultivars, you can have iris blooming virtually all season long in your garden.

The Misunderstood Iris

Homeowners and landscapers that are not experienced gardeners usually don’t realize the wide variety of irises that are available to them. Most of us can only identify the common bearded iris (iris germanica) with its broad sword-like leaves and its traditional floppy purple blooms. In this post, we’ll introduce you to a handful of other iris species and let you know how to plant them so that you can enjoy them from April until September. All of them are easily available from most well stocked nurseries (or over the internet), and all of them are relatively easy to grow. So, let’s get to know some of them…

Early Blooming Irises

Iris reticulata (Iris reticulata) is the earliest blooming of the irises we’ll discuss here. It is a bulb and therefore must be planted in the fall.

Iris reticulata in bloom

Iris reticulata is a low growing colorful iris that blooms brightly in late March in the Northeast. Its flowers are borne on short stems only about 6 inches high or less and the foliage is very thin and grass like. The blooms usually last into mid-April and then the plant virtually disappears. Unlike most bulbs, it doesn’t go through an ugly phase after blooming. The flowers come in several different colors, but it is most easily found in shades of purple. Since the flower is so small, you will want to plant several (think groups of 50-100 bulbs) to make a statement. Plant this iris in a sunny spot where it will be easily visible. They only need to be planted a few inches deep, so they’re easier than most bulbs. The only drawback to Iris reticulata is that it sometimes peters out after a season or two, so you may have to add additional bulbs to your planting in subsequent years.

Don’t bother looking for this iris in the nursery. Since it is a bulb , it is easiest to buy via mail order or over the internet during the spring or the summer. Buy it in large quantities. Each bulb will only produce one small bloom.

Dwarf Bearded Iris (Iris pumila). This iris looks like an exact miniature of the more common, tall bearded iris (Iris germanica). The flowers are big and showy, and come in all colors of the rainbow.

Iris pumila “Manhattan Blues”at Highland Park, Pittsburgh

The foliage is wide and sword-like, and even better looking than its taller cousin. The entire plant is roughly 10-12 inches tall and very compact. Blooms appear in early May and usually last for two weeks. Iris pumila likes well drained soil in a sunny location. Most larger nurseries will carry Iris pumila in containers, but it may be harder to find than other irises. The major drawback of this dwarf beauty is that it experiences a very ugly phase after blooming. Cut flower stalks to the ground, and foliage to about three inches high, after blooming is done or whenever the plant starts to look unsightly. This will help keep a tidy look, and foliage will regrow within a few weeks.

Crested Iris (Iris cristata) This iris is so small, it is usually considered a ground cover. The flowers, however, are showy and plentiful, so it makes an impression even if it only gets four-six inches tall. Unlike most garden irises, this one likes the shade and will spread vigorously, creating a mat of lovely, wide, grassy foliage and beautiful blooms.

Crested iris (Iris cristata)

The crested iris blooms mid to late May , so it might be in bloom at the same time as Iris pumila depending on where you are located. Don’t let this stop you from planting it. Since it loves shady spots, it can occupy a part of your garden that Iris pumila (and most other irises) won’t tolerate. Bloom color ranges from white through the blues and purples. The foliage also stays great-looking even after the bloom is finished, so there is virtually no maintenance required. The only drawback to the crested iris is the short bloom time (only about a week), but its graceful foliage keeps this plant looking great all season long.

Mid-Season Irises

Tall Bearded Iris (Iris germanica) This is the most common iris in the gardens of the northeast. Its large, showy flowers are familiar to most of us. This type of iris has been cultivated extensively, so there are literally hundreds of varieties available. Tall bearded irises have wide leaves that can appear almost blue-green. They bloom just after Iris pumila in mid to late May and can last two-three weeks.

Tall Bearded Iris (Iris germanica)

Tall bearded iris is easy to grow, as long as it is planted in well drained soil and gets full sun. This plant will not tolerate wet feet. Depending on the variety, heights of flower stalks usually vary between two and three feet. The flowers bloom above the foliage, so the plant is somewhat shorter when not in bloom. Flowers are available in all colors of the rainbow and newer varieties will even rebloom in late summer or fall. There are two major drawbacks of the tall bearded iris. One is that the flower stalks sometimes need staking. This varies widely depending on conditions and the variety. The other drawback is that, like its cousin, Iris pumila, it will get very unsightly looking after blooming. Cut back foliage to about six inches after bloom.

Siberian Iris (Iris sibirica) The Siberian iris is a truly graceful plant. It is easier to grow than bearded irises and it maintains lovely foliage throughout the season. It has a tall, slender habit with long green grass-like leaves. Flowers appear slightly later than bearded iris, but the two varieties will overlap for most of their bloom.

Siberian iris (Iris sibirica)

Blooms are available in many colors, but the most common varieties are variations of purple or white. Foliage is typically between two and four feet tall with flowers blooming slightly above the foliage. Siberian iris needs more moisture than the bearded varieties, but it is very versatile. It can take both full sun and part shade. It really has no significant drawbacks. Its bloom period is a little shorter than the bearded irises and the flowers are less showy, but the overall effect is very graceful and elegant. Most importantly, the foliage looks great even after blooming is done.

Japanese Iris (Iris ensata) Japanese iris is by far the most elegant of all the irises.

Japanese iris (Iris ensata) courtesy of Monrovia

The habit is very similar to the Siberian iris, but the flowers are larger and much more showy. Japanese irises bloom after Siberian irises are past, from late June through mid July. The flowers can be absolutely breathtaking. The flower heads are almost flat and very large, on tall delicate stems. Japanese irises can be a little finicky and need a lot of moisture to thrive, especially up until the time they bloom. It may be for this reason that they are so underutilized in northeast gardens. Japanese irises prefer a moist location in full sun and can even live with their roots submerged in water. If you do not have a moist area in your garden, create a depression in the garden and use plenty of peat during planting. This is their only drawback, otherwise the plant is very low maintenance and the foliage stays looking great all season long.

Late-Season Irises

Reblooming Bearded Irises. Various tall bearded iris cultivars are now available that rebloom in the late season garden. These repeat bloomers have different types of reblooming patterns and may behave differently in different climates.

Reblooming iris “Immortality” courtesy of Monrovia

However, there is one cultivar that is both a reliable rebloomer and easy to find at your local nursery. “Immortality” is a tall bearded iris with white flowers that blooms along with other tall bearded irises, then reliably reblooms in late season (usually August or September). The late season bloom will not produce as many flowers, but it is still a welcome sight in August or September. “Immortality” looks and behaves just like any other tall bearded iris, so follow the same planting guidelines.

Planting Your Iris Garden

Now you know the right irises to buy, so you can get started planting. These irises can be planted anytime you buy them with the exception of iris reticulata, which can only be planted in the fall (anytime before the ground freezes). Just a few things to remember…. The bearded irises need lots of sun, so place them accordingly. The Japanese iris needs lots of water, so water it regularly or plant it in a depression that can collect water naturally. The crested iris likes shade, so give it a nice shady spot close to the edge of your garden where its small size won’t be an issue.

Once again, here is the final line-up for iris blooms all season long:

Iris Reticulata (Iris reticulata – any variety), Dwarf Bearded Iris (Iris pumila – any variety), Crested Iris (Iris cristata – any variety), Tall Bearded Iris (Iris germanica – any variety), Siberian Iris (Iris sibirica – any variety), Japanese Iris (Iris ensata – any variety), Reblooming Iris (Iris x germanica cultivar “Immortality” suggested).

This bloom calendar should help you plan your garden:

Bloom times for iris varieties

Enjoy your beautiful iris blooms and don’t forget to buy your Iris reticulata bulbs in the spring or summer so you can plant them in the fall!

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