If there’s one thing that all plants in the Iris (EYE-ris) genus are known for, it’s their spectacular blooms.
These plants are generally considered to be easy to care for and will continue to bloom for many years when cared for, but sometimes, things can go wrong, and your iris will fail to bloom.
Here are the many reasons this can happen and what to do about it.
Why is My Iris not Blooming?
There are three significant factors in an iris failing to bloom: age, health, and proper care.
When any of these go wrong, it can fail to bloom.
An iris can live for quite a few years, so it takes time to mature.
For example, an iris planted from seeds won’t bloom until its second year.
Likewise, an iris can grow past its prime.
The Siberian iris is a prime example of what can happen when a plant grows too old.
These plants will eventually form a ring of healthy rhizomes while the older central rhizome slowly dies out and may be replaced by weeds.
It’s a clear sign that it’s time to divide the plant, discarding the older rhizome and replanting the younger sections.
Watering an iris properly is essential, as too much or too little can lead to problems.
Too much water will lead to root rot and fungal disease, harming or even killing your iris plants.
In such cases, you may have to dig up the plant, remove diseased portions, and plant it in fresh soil.
Depending on your iris, the plant will generally need to be watered when the soil feels dry, approximately+ 1” to 2″ inches deep.
Not enough water can stress the plant out, resulting in it failing to bloom, so using the soak-and-dry method is an excellent way to ensure the plant is getting just the right amount every time.
Irises love the light and will fail to bloom if they’re not getting at least 6 hours of full sun per day.
In places where the midday sun is too harsh, this exposure can be in the morning or evening.
You can tell if your iris is getting enough light simply by checking it every hour on a sunny day to see when it ends up in the shade and when it’s getting full sun.
Infestation or Infection
Overwatering and exposure to sick plants can cause your iris to become infected or infested.
It’s not uncommon for an infestation to happen due to a fungal infection, such as the case with fungal gnats.
Likewise, piercing insects produce honeydew, which can attract some forms of fungus.
Because both of these problems can cause the plant stress and drain its resources, they may prevent the plant from blooming.
Practicing proper care techniques and occasionally checking for signs of an infestation or infection is often enough to ensure your irises never get too sick to produce blooms.
As with all things, your iris needs its nutrients in moderation.
Too much nitrogen or not enough phosphorus will make the plant focus on foliage rather than flowers.
Additionally, your plant will fare best in slightly acidic soil.
When in doubt, perform a soil test to see if you need to adjust the fertilizer you’re using or augment with organic compost.
Giving your Iris some bone meal in the early spring will also help encourage healthier blooms.
Overcrowding is a problem that becomes more common as your iris ages.
When the clumps get too big, the individual rhizomes will compete for resources, causing the entire chunk to suffer.
For this reason, it’s best to divide your irises every couple of years, even if you aren’t trying to propagate them.
There are several critical differences between iris rhizomes and iris bulbs that are easy to overlook. Many insist the two are the same thing.
However, cutting open a rhizome will look like potatoes or other tubers; it will layer bulbs much like an onion.
More importantly, bulbs and rhizomes need to be planted at different depths, or they may fail to bloom.
As a general rule, a rhizome should be planted so that the top third is above ground.
Bulbs should be planted three times as deep as their size (i.e., a 2″ inch bulb should be planted in a hole 6″ inches deep).
Keep in mind that adding mulch or compost over an iris will affect the depth of the bulb or rhizome, and it should be avoided.
Finally, the health of your bulb or rhizome can affect the plant’s ability to bloom.
Check the root system for soft spots or a foul smell when dividing or transplanting.
Discoloration or odd shape may also be signs of a sick tuber.
In many cases, you can safely cut away the diseased sections until only healthy tissue remains, saving the plant.
However, sometimes the damage is so extensive you’ll have to discard the whole plant and start over.