7 Tips For Getting Your Irises to Rebloom

Scratching your head over a patch of irises that never bloomed? Or thrilled with your iris flowers this season and determined to enjoy a similar bounty next year? Certified master gardener and landscape designer Liz Jaros shares 7 tips for getting your irises to bloom fully and faithfully for many seasons to come.

iris rebloom


Disappointed by modest, lackluster blooms? Fortunately, an iris can rebloom with the ruffly, full-color thrill you expected. Even if you had a ‘leaves only’ season where there were no flowers at all, rest assured that irises take a few years to establish, and many do not perform well initially.

Even if this was your second or third year, and a clump of irises that once bloomed beautifully is no longer sending up flowers, you may have to make a few tweaks to make them productive again.

While generally considered easy to grow, the genus does have quirks and preferences that demand your attention. Here are 7 tips for getting your irises to bloom again next year.

Give Them Plenty of Sunshine

Close-up of blooming purple irises in a sunny garden. The plant has long, sword-shaped, smooth, bright green leaves. The flowers are large, showy, with six petals arranged in a unique pattern. The three outer tepals are called "falls" and the three inner ones are called "standards".
Ensure these plants receive a minimum of 6 hours of sunlight daily; check annually for any changes in their sun exposure.

Irises need at least 6 hours of sun per day if they are to flower to their fullest potential, and you should evaluate their location every year to ensure this demand is met. Has a tree or shrub grown over them to shade out some of their daily rays? Has something changed in the landscape to reduce the hours they spend exposed to direct light?

If your irises aren’t flowering, exposure is one of the first suspects to cross off your list. Even if you’re pretty sure they’re getting enough sun, take a day to record their exposure level at each hour as the sun makes its way across the sky. This will help you know if they’re getting the required 6 hours, which do not have to be sequential but must add up to 6.

If you discover they are no longer (or never were) planted in full sun, find a new spot in the yard that can meet their needs. Transplant them in fall or early spring, and you can expect a more impressive floral display next season.

Make Sure They’re Not Planted Too Deep

Close-up of planting an Iris bulb in the soil. The gardener's white-gloved hands are digging in a planted iris bulb with a small black spatula with a green handle. The appearance of the bulb is elongated, knotty, covered with a brown wrinkled skin. Green flat sword-shaped leaves sprout from above the bulb.
For successful iris planting, bulb irises should be buried four inches deep.

Improper planting depth is the mistake new gardeners and inexperienced iris growers are most likely to make, so I can’t emphasize this enough; Bulb irises should be installed four inches deep with the pointy end up and covered with dirt, but rhizome irises that are planted too deep will not flower. They must sit just below the soil surface with a little bit of rhizome exposed above the ground.

We are so used to digging a hole, dropping in a plant, and covering it with dirt (a process that works just fine for many of our less persnickety green friends) that it’s easy to think this rule can be broken. But when it comes to irises, if you don’t follow the recommended planting depth exactly, you will be disappointed by their show of blooms.

To make sure you plant your iris at the right time and depth so it will flower again (and again), follow these directions:

  1. Dig a trench (or a hole if you’re just planting a single iris) and mound some dirt up in the center.
  2. Carefully set your iris rhizomes on top of the mound.
  3. Make sure leaf fans are pointed up and hairy roots are pointed down.
  4. Let the root hairs cascade down over the mounded center so they extend toward the bottom of the hole.
  5. Backfill with dirt until just the tops of the rhizomes remain exposed.
  6. Water lightly and regularly until established.

Don’t Overwater

Watering blooming irises in the garden from a large yellow watering can. Iris plants have upright stems with large and exquisite purple flowers. The leaves of the iris grow in bunches or fans from the rhizome, they are long, narrow, bright green in color, in the shape of swords. The leaves are smooth and have a waxy texture. The flowers consist of six petals arranged in two layers.
Water properly and discard diseased rhizomes to ensure healthy flowers.

Nothing shuts down a potential iris flower show quite like rotting rhizomes. As a plant with tuberous roots, irises are particularly susceptible to disease and decay resulting from poor drainage or overzealous irrigation. Water your irises evenly and regularly during their first season (or after transplanting) but never let them soak or sit in standing water.

Once established, your irises should only need water during periods of drought and extreme heat. So be careful not to give them too much water. If you suspect your irises are not flowering because they are waterlogged, dig them up and have a look. If they are squishy, slimy, or black, they are probably suffering from a moisture-related disease.

Unfortunately, a rotted rhizome will never flower again and must be discarded. Get some more irises and give it another shot. Now you know.

Divide Every Three or Four Years

Dividing iris plants in a sunny garden. Close-up of a dug up Iris plant from the soil in a garden. The plant has light brown rhizomes and bulbs. Iris has vertical long green leaves with a smooth, waxy texture. The leaves are shaped like a sword. Next to the dug up iris plant, there is a shovel and a wheelbarrow with black wheels.
Regularly dividing irises every three or four years prevents overcrowding and restores bloom potential.

This routine perennial maintenance task is not optional when it comes to irises. If you want your iris to rebloom reliably, ensure they don’t get crowded.

Although it takes them some time to establish, mature irises will multiply rapidly after a couple of years, and their rhizomes may take on a matted or buckling appearance. When this happens, leaf and stem growth will be suppressed, negatively impacting the generation of new flower buds.

To avoid overcrowded irises (and the inevitable reduction in blooms that results from it), you should plan to divide them every three or four years. This will restore their bloom potential, and you’ll have more irises to plant in other parts of the yard! Division should be done in the fall for best results.

Here’s how it’s done:

  1. Dig up the entire iris clump taking care not to damage roots.
  2. Lay the plant sideways on a tarp or hard surface.
  3. Using a flat-edged shovel or a sharp knife, slice the root clump cleanly in half.
  4. Repeat until you have several small clumps, making sure each section contains some leaves and some roots.
  5. Replant each section as you would a new iris, with leaf fans pointing up and root hairs draping down.

Try a Reblooming Variety

While most iris cultivars will only bloom once a year for about two weeks in late spring, some varieties will flower again later in the season. And others that will bud out two or three times more if they are properly cared for. If you can’t wait til next season for your irises to bloom again, why not plant a reblooming variety?

Reblooming irises perform differently in different hardiness zones, so keep your expectations tempered to your part of the world. Gardeners in cold regions will likely only get a spring and fall bloom, but southern gardeners with longer seasons might get several bud productions in the same year.

Many iris varieties fall under the reblooming classification, the majority of which are bearded varieties from the germanica species. Here are a few high-performing, reblooming cultivars you might want to try in your own landscape:

‘Best Bet’

Close-up of a blooming Iris germanica 'Best Bet' flower against a blurred background. The flower is large, spectacular, consists of two separate parts: upper standards and lower falls. The standards of 'Best Bet' are pale lavender in color and gently ruffled. They stand upright and form the topmost layer of the flower. The falls of 'Best Bet' are a rich violet blue, providing a striking contrast to the lavender standards. The falls have a downward-drooping or flaring shape, giving the flower a sense of depth and dimension.
‘Best Bet’ is a tall bearded variety with pale lavender standards and violet blue falls.
botanical-name botanical name Iris germanica ‘Best Bet’
sun-requirements sun requirements Full sun
height height 2-3 feet
hardiness-zones hardiness zones 3-9

This lovely tall bearded variety is gently ruffled with pale lavender standards and violet blue falls. It has subtle white veining near the throat and thick yellow beards.

Reaching heights of up to 3 feet on sturdy stems, this cultivar offers two to three flower stalks per plant and will flower again at least once in late summer or fall.


Close-up of an Iris germanica 'Champagne' flower against a blurred green background. The flower has scalloped lemon yellow petals with a slight ruffled effect. Creamy white beards are visible at the base of the Champagne petals. These beards serve as a focal point and create a striking contrast with the yellow petals. Standard petals are cream colored. Falls petals are pale yellow tinged with cream, with wavy edges.
‘Champagne’ is a fragrant reblooming cultivar with peachy-white upright standards and golden apricot drooping falls.
botanical-name botanical name Iris germanica ‘Champagne’
sun-requirements sun requirements Full sun
height height 2-3 feet
hardiness-zones hardiness zones 3-9

This elegant reblooming cultivar has a sweet orange blossom scent and a softly ruffled personality. Standards petals are peachy-white and firmly upstanding, while falls are golden apricot and down drooping.

‘Champagne’ has a golden beard the same color as its throat. You can expect this cultivar to bloom at least twice during the season.

‘Carmel Celeste’

Close-up of a blooming flower of Iris germanica 'Carmel Celeste' against a blurred background. The petals of 'Carmel Celeste' are scalloped and a beautiful warm golden color. Near the flower's throat, 'Carmel Celeste' displays a matching golden beard.
‘Carmel Celeste’ is a fragrant, reblooming dwarf bearded iris with lemon-yellow scalloped petals and creamy white beards.
botanical-name botanical name Iris germanica ‘Carmel Celeste’
sun-requirements sun requirements Full sun to part shade
height height 8-15 inches
hardiness-zones hardiness zones 3-8

This reblooming dwarf bearded iris has scalloped, lemon-yellow petals and creamy white beards. Despite its diminutive stature, it packs a colorful punch, growing roughly 15 inches tall. It has a spicy citrus scent and typically flowers in spring, mid-summer, and fall.

Do Not Cut Them Back Until Fall

Top view, close-up of pruning an iris plant with purple secateurs. The iris plant consists of vertical, long sword-shaped green leaves, and vertical thin stems with large, withered purple flowers.
Keep the green leaves after flowering to support bud development, and trim them to 4 inches above the ground after the first frost.

After flowering, most iris varieties will remain green and upright in the garden for the rest of the growing season. And it’s best to let them stay that way. Though you may be tempted to cut their leaves down once their flowers are gone, this will likely harm next year’s blooms.

After completing a flowering cycle, irises will use their leaves to harvest the sun and draw energy toward their roots.

Although it looks like they’re doing nothing but taking up space, your irises are actually working hard below the surface to create buds for next year. Leave them alone as long as you can, and cut them back to about 4 inches above the ground after the first frost. You’ll be rewarded with full bountiful blooms next year.

Pull Back the Mulch in Spring

Top view, close-up of Iris leaves in a garden bed covered with a layer of red cedar mulch. The leaves are vertical, long, flat, sword-shaped, blue-green.
Cover iris rhizomes with mulch to protect them from freeze-thaw damage, but remove it in early spring for healthy blooms.

Cover the rhizomes with 2-3 inches of hardwood mulch when all’s said and done for the year. Since roots are partially exposed, the genus is somewhat vulnerable to freeze-thaw damage, and mulch will help protect them from dramatic swings in temperature.

It will also help manage the flow of water and melting ice, discouraging it from puddling around a plant’s base.

With that said, it’s essential that you pull the mulch away from your irises in early spring. Uncovering the tops of their rhizomes will expose them to the sun’s rays and warming temperatures, encouraging healthy blooms for the season.

Final Thoughts

Growing irises can be frustrating, especially during the first few seasons, but once you get the basics down, they’ll be off and running.

Whether your flowers were spectacular this season and you want to make sure you get an encore performance next year, or you were disappointed by a poor showing and want to make sure it doesn’t happen again, with proper care and maintenance, you can up the odds your irises will bloom beautifully again for many years to come. 

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