8 Causes of Irises Not Blooming[How To Keep Bloom]

“If you truly love Nature, you will find beauty everywhere,” said the famous painter Vincent van Gough who created the most famous series of art named ‘Irises’.

You love Irises, right? Undoubtedly Irises are one of the most beloved flowers on earth.
Gardeners are very much fond of the Irises.

But if your Irises are not blooming then it is a serious matter of concern. Lack of knowledge about Irises may lead a gardener to such a condition where he or she finds that Irises are not blooming. Nobody will tolerate that, will they?

Lack of sunlight, overcrowding, inappropriate planting depth, less water stress, unhealthy rhizomes, excess nitrogen, etc are the main reasons why your Irises don’t bloom.

In this article, you will get the solutions to the blooming problem of Irises. So, without wasting your time, let’s get into that.

Why Are The Irises Not Flowering? [Problems & Solutions]

1. Lack of sunlight

Sunlight is important for any plant to grow well & bloom well. Lack of sunlight even stops the blooming. Irises need 6 hours of daylight for proper blooming. If your Iris plants can’t get enough sunlight, you will get paid for no flowers.

Control Measure

Make sure your Iris plants are getting enough sunlight. If there is any object or plant or tree branch which is casting a shadow on the Irises, remove that or take that away. So that your Irises get enough of the daylight.

Preventive Measure

Plant your Iris plants on the part of your garden where it can get all day long sunlight.

2. Inappropriate Planting Depth

Planting depth is very important for the proper growth of the Irises you chose to nourish.
First of all, you have to know that Irises have two groups. One grows from rhizomes and another from bulbs.

If you cut a rhizome you will find the inside of it like a potato where you will find the inside of a bulb-like that of an onion. In the case of the bulb, the planting depth will be thrice the size of it and the rhizome needs to be planned as one-third of it remains exposed above the ground.

Control Measure

Inappropriate planting depth is an agonist of blooming. So if you have found out that the planting of the Irises is done in the wrong manner, carefully replant them. Before replanting you should dig the soil and prepare it once again. I hope you will get the reward now.

Preventive Measure

Before planting the Irises, make sure the soil is well dug and well-drained. Now maintain the planting depth as described before. Do not install mulch to prevent weeds as it may block the sunlight. Sunlight is very important.

3. Overcrowding

Overcrowding is a serious issue in the case of blooming. If the Irises are planted too close they may not bloom. The reason would be less supply of nutrition and lack of sunlight. So proper spacing is another condition for proper blooming.

Control Measure

If the Iris plants are planted in a crowded manner, replant them according to the appropriate planting depth. Iris rhizomes should be put 12 to 24 inches far from one another. Irises get overcrowded every two to five years.

Whenever you find your plants overcrowded, replant them after digging them up and dividing the rhizomes.
Make sure the rhizomes are getting plenty of sunlight and the soil is well-drained.

Preventive Measure

Plant the Irises 12 to 24 inches far from each other on the bed. Dig up, divide and replant the rhizomes when the Irises get overcrowded. This can be done from late July till early September.

Make sure the irises are getting enough sunlight. Part of the rhizomes should be exposed. Deadhead the irises frequently and let enough foliage remain on the plants. You should cut the stalks and trim the plants when flowering is done.

4. Underwatering Stress

Irises do not need much watering. After planting they may need watering once a week. When established, Irises don’t need such irrigation except for drought conditions.

Control Measure

Overwatering may cause the rotting of the roots or rhizomes of the Irises. If such happens, replant them in a new soil bed & care for them well. Hope they’ll survive.

Preventive Measure

Be alert of overwatering. Do not water established plants unless drought occurs. You can keep a moisture meter to assess the water level of the soil of your garden (Our pick: Atree Soil Soil Tester Kits with Moisture, Light, and PH Test for Garden).

5. Unhealthy Rhizomes

Unhealthy rhizomes or bulbs may cause the blooming problem. Their health is very important for the growth of both plants and flowers.

Control Measure

If your Irises are not blooming despite enough sunlight and spacing, make sure the rhizomes or bulbs are okay down there. Dig them up and observe. If those are rotten or malformed, you need new fresh ones to replant.

Preventive Measure

Before planting check the rhizomes. Plant fresh and healthy rhizomes and leave a part of them exposed.

6. Excess Nitrogen

Appropriate nutrition is a must to grow healthy plants and get bountiful blooming. Gardeners often use fertilizers without knowing the right formula. Excess nutrition can become harmful. If you input excess nitrogen it will make the leaves grow instead of the flowers.

Control Measure

If there is excess nitrogen in the soil it will be harmful to the Irises. In that case, Leaching could be the solution. First of all, you have to dig up the Irises and put them on a temporary soil bed. Then you have to wash out the excess nutrients through irrigation. After that, you have to dry out the soil till it gets the proper moisture. Now you can replant your Irises.

Preventive Measure

Dig the soil well and prepare it as well-drained. Test for nutrition deficiency. Phosphate fertilizer is essential for blooming. You need a perfect fertilizer for your Irises to fulfill the nutrient demands completely (our pick: Dr. Earth Organic Fertilizer)

7. Insect Attack

Irises can get affected by insects. The Iris borer Caterpillar is such an insect that makes bores or holes on the Iris plants and reaches the roots and damages them. As a result, Irises fail to grow and you miss expected blooming.

Control Measure

If your Irises get affected by borer caterpillars, it is better to spray an ideal insecticide (our pick: Monterey organic Garden Insect Spray). I recommend using a commercial insecticide but, if you want to use homemade formula, here’s a recipe:-

#DIY Oil-Soap Insecticide


  • 1 cup Vegetable Oil
  • 1 tablespoon Dishwashing Liquid Soap
  • Water


Take a jar & pour 1 cup of vegetable oil & 1 tablespoon of liquid soap into it. After that, shake the mixture properly. And there you go. The application rate is 2 teaspoon mixtures per liter of water.

Preventive Measure

Stay alert to insects. If you find bores on them take necessary measures immediately. High moisturized soil and weedy Iris bed can be risky. Nurture the Irises to keep them safe from insect attacks.

8. Fungal Attack

Irises get affected by fungi such as Sclerotium etc. They are responsible for the root rotting. The fungal attack is alarming and needs an immediate steps to protect the plants.

Control Measure

Whenever a fungus attack gets spotted, take fast action. Use a proper fungicide (Our Pick: Bonide Copper Fungicide).and change up the soil bed. Hope your Irises survive and continue to bloom.

Preventive Measure

To take an upper hand over the fungal attack, you can implement good fungicidal agents to prevent fungal attacks. Stay alert of fungal attacks so that you can take quick action.

Frequently Asked Questions

What month do irises bloom?

Irises have varieties. Some bearded Irises bloom from early spring to early summer where some beardless Irises bloom from late spring to mid-summer and some other species bloom from mid-spring to early summer. So as a whole Irises start blooming during early spring to late summer.

How many years will irises bloom?

Irises are regarded as perennial. It depends on care. A well-nurtured Iris plant blooms for many years.

Do irises bloom every other year?

Irises may bloom every year if nurtured well. But skipping for a season is quite common. Therefore the Irises may bloom every other year as they are regarded as perennial.


There are about 300 species under the genus Iris. Irises are a common garden flower as well as their blooming problem.

I tried to cover the reasons and their solutions for the blooming problem of the Irises. Hope you have got a pretty clear idea of why your irises are not blooming.

Take the necessary steps and let these lovely flowers bloom to increase the beauty of your beloved garden to a great extent.

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