Irises are one of the easiest flowers to grow. They stem from rhizomes, which quickly multiply over the years, producing bigger, wider stands of these appealing blooms. When you notice iris plants not flowering, the cause can stem from a variety of issues including weather, soil fertility, overcrowding, unhealthy rhizomes, insect or disease attack, planting depth and even site conditions. If you are wondering, “why are my irises not blooming,” take a good luck at these issues. Usually, we will find iris plants not flowering due to one of these easily corrected conditions.
Bearded or Asian, classic or designer, irises are a pleasure to have in the garden. They provide a long term display of tall, glorious sword-like leaves and boldly featured blooms. Most irises have a wide hardiness range from United States Department of Agriculture zone 4 to 9. When iris do not bloom, you still have beautiful foliage but the long waited for flowers refuse to appear. Frustrating as this is, it is generally something that can be fixed and flowers will appear the following year.
There are many reasons for irises not blooming well, but what about why irises won’t bloom at all? Most species of iris spring from rhizomes, although a few come from bulbs. Both these are underground storage structures that contain a reserve of carbohydrates and embryonic plants. When temperatures and lighting are right, they sprout stems and leaves and eventually produce flowers.
Poor rhizomes or bulbs are often the cause of no flowers. If these are mushy, rotten, small and under formed, then the result is stunted plants with few or no blooms.
Also, the plant needs well-drained soil in full sun for flowers to be produced. Irises in shady locations may fail to form blooms.
Depth of planting can also cause iris plants not flowering. Rhizomes should be near the soil surface, ideally with the tops at or slightly below the soil surface.
If plants are correctly installed, have well-draining soil and good light exposure, it may be a soil fertility problem. Conduct a soil test to see if the pH and fertility are consistent with good iris growth. Ideal iris soil pH is 6.8 and soil should have average levels of nitrogen, but sufficient amounts of phosphorus too, the nutrient that helps plants form flowers. An amendment of superphosphate, colloidal phosphate or bone meal applied in early spring can help plants develop blooms.
Another reason for iris plants not flowering is overcrowding. The rhizomes will increase over time and plants become too packed in their site. Dig up the clump and divide it, planting each rhizome individually in other areas of the garden. Retain just half the rhizomes in the existing area and water all transplanted rhizomes frequently.
Over competition from other plants and weeds, which shade the iris bed, and insufficient water are other causes for why irises won’t bloom. Irises are extremely drought tolerant but in the absence of any water, they will respond by refusing to bloom.
Another commonplace reason is a late freeze. Although irises tolerate freezing conditions well when not sprouted as long as the area is well draining, early leaves and stems can succumb to a freeze. When there are no leafy greens to draw in solar energy, flower production can screech to a halt. Also, a freeze can kill any new buds that are just forming. Freezes experienced by plants 6 to 8 weeks before bloom can simply abort the buds and prevent iris plants from blooming for a season.
Insects and disease are seldom a problem, but if plant health is compromised, buds will rarely form.
I planted an iris I bought on eBay (before I found Dave's) it's been so long I can't remember for sure but I seem to remember it was a German Iris,. When it didn't bloom the first year I thought, well, what did I do wrong. Turns out I planted it too deep, I learned. When I dug it to fix that problem, I discovered that it had many new tubers and I divided it and planted both groups of tubers as directed by the iris experts on Daves. I understand it sometimes takes a year for them to adjust to a new location, so I waited. Three years now, no blooms. Absolutely gorgeous foliage that looks lush and very healthy, and it is obvious that both clumps have multiplied A LOT! Did I get a dud? Could it be something besides an iris? I bought some kind of lily once on eBay that turned out to be a pregnant onion, LOL.
Can you furnish a pic of the foliage and the way you planted the rhizomes?
I will get some pics tomorrow. When I replanted them, I made sure the rhizomes were about half above ground, I remember Dg's telling me they liked to sunbathe. I can still see the rhizomes if I pull the foliage away (it's very dense). I wish I could remember what I bought them as it's been so long and it may not even make a difference - was it a German iris or Japanese? I have even treated these babies with Messenger, hoping that would spur them to bloom. No luck. I appreciate any help.
At least the foliage is pretty.
Here's a pic of one of the replanted clumps. This one gets almost full sun, the other one gets some afternoon shade. Both clumps are about the same size, and earlier this spring before they got so dense, it was apparent that these were the"daughters", as the center was empty and surrounded by four plants.
Please excuse the weeds it's all I can do to do a little every day, and right now the veggie garden is taking most of my time. That and my little helper.
Miss Emily was telling her baby doll how much she liked the daylilies. What a joy to have a grandchild (17 months) that shares my appreciation for flowers. I love her "oohs" and "aahs". She tries to say "pretty" but it sounds more like "kitty".
That is interesting. The pic shows a healthy, disease free plant. Leaves show good color
but are a bit small for this time of the year. A very wild guess would be plant nutrition. The
plant is not storing the proper nutrients for blooming. Maybe some of the members in the
south east will come in and give you a better diagnosis.
They normally should be in full bloom by the second year after planting. Roughly 40% will
bloom the first year after planting. You are well within the usda zone requirements and
irises do not require a chill time so there is no obvious reason why they will not bloom.
Thanks for that response, I had not considered that as an issue. I feed all my flowering plants routinely, e.i, bimonthly, with Miracle Grow for flowering plants. The soil is clay & rock amended with composted cow manure, which has improved the texture of the surrounding soil tremendously I actually have earthworms now! Think I should have the soil tested?
From what I have picked up from this forum and others, it would or could be the PH of the
soil. If the PH is skewed too far either way, plants cannot take up nutrients regardless of
the amount in the soil. Take it from a person who limed azaleas. It took about 3 years of
sulphur and bone meal to get them started.
Again, this is just an unsupported guess. Try checking with other gardeners in your area.
Soil tests are always beneficial if obtained at a reasonable cost.
I think a soil test is a good idea, too.
If I am not mistaken, it is not an uncommon practice to apply "Bulb Booster" or some other good source of phosphorous annually. Phosphorous is the main macronutrient associated with flowering and fruiting. This might be a good time to do it.
If you would like someone to test a rhizome, I would be willing to try an experiment to see if it would bloom here in NY. Just mail to me in a bubble envelope. I have a few others I am testing to see if I can match up for correct identity.
Just a thought, but when you divided it, did you plant the individual rhizomes, or did you just divide it into smaller clumps. It looks to me like it needs division.
I divided the one large clump and replanted the two resulting individual rhizomes in two separate locations on opposite sides of the yard, using the instructions I received from DG'ers here. That was two years ago and I am still waiting for the first blooms. :( I was told it may take a couple years for them to recover from being relocated? If you'all think they need to be divided again, I can do that and I will be glad to send you one, Pollly. I probably won't be able to get to it until the weekend, though. Thanks for all the help!
I know you are pressed for time to weed, but only the hardiest iris will bloom if grass is growing in it. I had an entire row that did not bloom this year because I wasn't able to weed the grass out of it! A row I planted the same time that I did get weeded bloomed like crazy. Could be just another peice of the puzzle.
I'm curious what's on the other side of the fence? Is it a pet area?
Okay - ph is 6.5. I think that's pretty normal, right? I will get some more weeding done tomorrow and Thursday if all goes as planned ( I have Miss Emily this weekend so no "real" gardening will get done then, LOL). Steve, the area just on the other side of the fence is actually one of the few places in the back yard that is off limits to the pets. It was previously just yard, but last fall we sectioned off the area for a small raised bed in which we grew some fabulous onions this spring, and I have just turned over the soil to try to decide what to do with it next. It is fenced w/chicken wire to prevent the kitty from using it as a litter box when she's outside.
But since you mention it, I am wondering if the neighbor dogs are tinkling on my irises. My dog is the only one in the entire community that is fenced in 24/7/365. We have no leash law in the county, and I don't really have a big problem with it, but since both plants are on the opposite corners of the lot, they would be in logical places for the doggies to sprinkle. They usually find the tires on my van, but who's to say they aren't spreading it around.
I'd like Dee to take a look and see what she recommends. To me it looks like it needs to be divided. I'll ask Dee to come over.
Doggie tinkle is a rich source of nitrogen. It looks like there is a sort of path worn to this corner as if there is some traffic.
Dividing will probably help. Remember to add some phosphorus.
Well upon looking at the area closely here is what I would recommend, first sometime this summer July, August, Sept, dig them, get them in an area where you have more control on weeds, animals and DIVIDE them. Iris do not like to get too crowded. This is why commerical growers must divide at least every 1-2 years.
If you have any further questions please dmail me and I will answer, until July 1 because then I start digging all the commerical orders. I have 3 acres, bearded all sizes, siberian, japanese, spuria, daylilies, lilies, seedlings of others.
Thanks so much for all the great advice. The more I look at it, the more I am thinking that there are a multitude of issues here, most of which will be corrected by digging up, dividing and relocating them. I am really jealous, since my daughter moved into a home 5 years ago with several iris beds, has never touched them and was loaded with blooms every year. I hope my granddaughter has more interest in gardening than my darling daughter does. Her idea of interest in the garden is asking when the cucumbers and tomatoes will be ready.
I bet she will. It seems to skip a generation. My daughter does do some gardening, not much, but her daughter, aged 7 is just crazy about it, and loves iris. She even told her mother how to plant an iris, like a duck sitting on water, Mommy.
You would think with as much as I have that my daughter would have a little interest NOT, but like you my grand daughter loves to garden, does not matter what. she also is one of the best in the business of iris rhizome cleaners:) I put that almost 12 year old against any one as far as getting them and quickly:) At least someone, and my son loves to make crosses.
It's so much fun when the younger ones are so excited about it.
Polly and Dee,
You have both given me hope. My daughter and I are very close but have no hobbies to share she scrapbooks mostly, I garden and make jewelry. She also blames me for not teaching her how to cook. Hey, nobody taught me!! My little munchkin, 17 months old, has learned the path to not miss ANYTHING in bloom, and today she carried around a pink petunia bloom for 2 hours, put some of my first dahlia blooms in her little vase, and met the 2nd bloom open of "Lady Emily" daylily, purchased in honor of her. When I asked her what she thought of "Raspberry Pixie" and she said "Bebe" translated - "baby". She loves Grandma's garden and nothing could make me happier, except maybe when she gets older she can help me pull weeds!!
How cute. My grandaughter has been 'tromping' through the garden since she could walk. And picking flowers. At four she began to understand not to trample. And it's been uphill since. She helps me make the tags for my irises, and helps me plant them. She picks out some of the ones she wants, and takes a piece home, and really is overjoyed when they bloom.
Don't hold your breath on the weeds though. Both my granchildren find that BORING. How I hate that word, LOL.
Sometimes the gardening bug takes a while to bite.
My parents grew vegetables in rows when I was I child. No flowers just long rows of stuff I didn't care for. In retrospect, I think they saw gardening as another chore. And in midlife they gave it up. But I remember visiting my grandfather in Ohio when the snow was deep on the ground. He proudly descended into his cellar and brought up six apples which he lovingly cut into sections pronouncing their names "Winesap, Jonathan, Cortland, . " There was a love of growing things there that was undeniable. But through my childhood and early adult years I found gardening BORING.
Then, when I was 35 I discovered a little gardening center that I thought was really cute. And I fell in love with the smell of fragrant flowers. I started with fragrant confederate jasmine which grew like topsy in Austin TX, filling the air with fragrance. I tried lilies, daffodils, old roses. And had success with a few. Once in a while I try vegetables. And on rare occasions I have succeeded. The basil in my new raised beds is flowering and filling the air with its own fragrance. And the shallots I planted last fall are blooming.
The most odious of chores in the garden, I think, is weeding. And I have come to look forward even to that simply because I love to be in the garden!
LOL, Steve, I SO get it. When I was a child I couldn't understand why I was being tortured by being dragged out of bed at 6 am to pick field peas and butterbeans at my uncle's farm, so early of course because any later and we melted in the SC July heat and humidity. Why couldn't we just buy them at the store? They usually found me hiding in a row of tomatoes with juice running down my chin. A privileged only child, of farm-grown parents who grew up raising not only their own veggies, but meat as well, I didn't appreciate any of it until my late 30's. I have always loved growing flowering plants, a double green thumbitis inherited from grandparents who were masters at making stuff grow, but until moving here I never had room or time to plant in earnest. Now even my semi-retired DH has turned into Farmer Vince, only lacking the overalls. He still doesn't know what he's doing but he loves to piddle. And he is crazy over all my flowers, very supportive of my never-ending need to fill every single spot with something blooming, as long as I find time to bring in some so he can admire them while in the house.
Guardians, I just found this post, and I didn't read all the way to here.
has anyone suggested to you to get rid of your iris and try again from a reputable grower? Irisloverdee sells. so do several others on here.
I think she is being polite too, as she was the one that first alerted me to the fact that there are folks on ebay that sell mislabeled and dud irises. fact is, irises grown from seeds are sometimes non-blooming. Duds. hybridizers I know have used this number often: only about 1 in 1,000 iris seedlings is good enough to keep.
you've spent so much time on these - but I usually get bloom (about 60-80%) that first spring.
get the weeds under control - that will stop some blooming - but also while you're at it, get some good plant stock.
Beardless irises will be a beautiful asset to your garden if you meet their cultural requirements. Whe the rhizome arrives, the plants will have been wrapped in damp paper and plastic bags. Immediately remove the rhizomes and soak the roots overnight in water. This will allow the plant to replenish the water lost in transit and get the plant off to a good start in your garden. Do not let the roots dry out during transplanting.
Beardless irises are generally planted in the fall but may be planted in August, September and October depending on your climate. The fall usually brings rain to supplement watering and roots will grow well as the weather cools. If you don’t have early fall rain be sure to keep them watered so they get a good start. The new root growth is needed to anchor the plants before winter. Plant your iris at least four weeks before your first hard freeze or killing frost.
Most beardless irises need a sunny location for best performance and bloom. If plants get less than a half-day of sun they may not bloom well. Siberian irises like even moisture while Japanese irises like as much water as you can provide. These types do not, however, like to have wet feet in the winter time. Louisiana irises and several of the beardless species will grow in standing water year round in the south but will also do well in the ground as long as they get enough water and don’t dry out. Spuria irises require dry conditions during their summer dormancy in July and August. More type specific growing instructions can generally be found on the websites of their respective section. (See About AIS)
Your beardless irises will thrive in a good garden loam with added organic matter such as humus or compost. An acid soil is preferred, but Japanese irises are the only beardless irises that require an acid soil. A pH of 5.0 to 6.5 is needed for optimum Japanese iris performance.
Plant Louisiana, Spuria and Siberian irises about one inch deep. Japanese should be planted a little deeper, about two inches, as they make new roots on top of old roots. Keep newly planted rhizomes well watered until they show active new growth. Drying out at this stage will result in almost certain plant death. Once established, beardless irises grow well, but extra care is needed to start them out. After plants are showing new growth, add a mulch of two to three inches (except on Spurias) and leave it on year round. This retards weeds and allows the roots to remain cooler. Also it prevents sun scalding to Louisiana rhizomes.
The soil type for your area will determine your fertilizer needs. For optimum growth an application of a balanced fertilizer in the spring is recommended when the plants are a few inches high. Japanese are especially heavy feeders and appreciate a second feeding before bloom time.
It is important to keep your iris beds free of weeds for optimum growth. After bloom is finished, cut off the bloom stalks before any seedpods made by bees develop as seeds from these would contaminate your named cultivars. Beardless irises can grow for several years in the same location if fed on a regular basis. Japanese irises are the exception – they must be divided every three years to thrive. After fall frost, clip off brown foliage to discourage rodents from nesting in the clump. Louisania foliage in southern climates will remain green and should not be cut off.
Want to know why irises do not bloom, how to care for them and when to transplant? Then this article is written just for you. Often gardeners call irises orchids. And in fact, this comparison is justified. Their beauty and diverse color are in no way inferior to northern beauties. However, not all varieties are equally successfully acclimatized in our country. And we begin to wonder why irises do not bloom. With proper care, these flowers will delight you for many years with their beautiful buds.
Irises love the sun, so when you choose a place in your garden, be sure to give them the sun. As a rule, compost or manure is bad for irises. The most suitable for their cultivation is light loamy soil with a neutral or slightly acidic reaction (pH 6-6.5). Once you have found the perfect place for them, prepare the site about two weeks before planting, so that the land has time to settle, otherwise the iris plots in fresh soil may go deep.
It is better to plant and transplant plants during the period when they finish their flowering. Because in this period the roots begin to actively develop. You need to plant a flower so that the rhizome is on the surface. After the iris has been planted, it is necessary to moderate the plant. If the sun during the transplant period is active, it is better to temporarily shade the landing site.
Irises are transplanted every three to four years, since they grow greatly during this time. And this can lead to diseases and wilting of the plant. When transplanting, divide into smaller parts of the rhizome. Inspect thoroughly all roots, cut off decayed or damaged areas. Seedlings of flowers from each other for 12-24 centimeters, the less often the plants are planted, the less they will require care.
These flowers do not need abundant watering. Watering should be done in the evening. Irises, when blooming, must be protected from water on their buds. In case of frequent rains, it is necessary to cover irises with waterproof material.
The first top dressing should be done early in the spring. The plant in this period needs nitrogen and potassium. When the soil dries, add ammonium nitrate, and then potassium salt (20-30 grams per square meter). Also, nitrogen-potassium top dressing must be applied during the budding of the plant.
For the aesthetics of the bush, wilted flowers are removed, and then the peduncles are cut off at the base. The cut is treated with crushed coal.
Why do not irises bloom? Even experienced gardeners do not have a clear answer to this question. But some factors affecting this process can be called.
Reasons why irises do not bloom :
In areas with cold winters, it is recommended to cover young irises with straw or leaves. In the spring, remove such a “cover” as early as possible.
General garden care
Keep the area clean and free of weeds and debris, this will allow the tops of the rhizomes to be always in the sun. Healthy green leaves should not be touched, but diseased and dried ones should be removed.
Iris x germanica ‘Best Bet’ blooming in October. Source:Moonik, Wikimedia Commons
This seems to have been a special fall for bearded irises in Northeastern North America. Several readers have written over the last few days (early October) to tell me that their irises are blooming for a second time. And these are irises that normally only bloom in late spring/early summer. My correspondants seemed especially concerned as to whether this off-season bloom would harm the plant.
Well, let’s answer that right off the bat: probably not. Plus it’s not as rare a phenomenon as you might think.
Plenty of Plants Rebloom Occasionally
There are quite a number of spring-flowering plants that occasionally rebloom in fall, including oriental poppies, primroses, perennial geraniums, lilacs, rhododendrons, azaleas, magnolias and iris. Usually this happens when the plant has undergone some kind of stress, such as a long period of drought or an exceptionally hot summer. However, sometimes there is no clear explanation. The plant simply starts to bloom outside of its normal season and no one knows why. And this out-of-season flowering is not really detrimental to the plant: it usually resumes its normal cycle the following year.
(Sometimes it’s best not to ask questions, but just to enjoy the result!)
Blooms in the fall usually do mean lighter bloom the following spring. That’s because the branches, stems or rhizomes that bloomed off-season won’t have time, at least in cold climates, to produce new flower buds for the upcoming spring. On the other hand, fall flowering is generally rather sparse and therefore it doesn’t necessarily have that much of a negative impact on the spring bloom to come.
Iris x germanica ‘Immortality’: probably the most popular reblooming iris. Photo: Iris Wiki
So much for regular bearded irises blooming in the fall, but there are also iris cultivars that naturally rebloom, that is to say, irises that bloom as usual in the spring, then a second time at the end of the season (August, September or October, depending on the local climate). They’re even offered in plant catalogs under the name reblooming irises.
In order to flower a second time, however, reblooming iris need the very best in growing conditions: full sun, good drainage, rich soil, regular fertilization (they prefer fertilizer not overly rich in nitrogen), little competition, etc. And they must be well established: rarely will they bloom a second time the first year.
Reblooming Iris x germanica ‘Presby’s Crown Jewel’. Source: Iris Wiki
Also, although these irises are generally just as hardy as the other bearded irises, that is, to zone 3, they only tend to rebloom in regions with long summers. So it’s unlikely they’ll rebloom in zones 3 and 4, where summers are short, and rebloom is rare even in zone 5. It’s in zone 6 and warmer that this trait is the most reliable. But even in Zone 7, and despite the best care in the world, reblooming irises don’t reflower every year.
Reblooming is also unreliable in areas that with hot, humid summers, such as the US Gulf Coast, in spite of its mild climate. Hot, humid weather seems to stress reblooming irises … and not in the right way. In California, on the other hand, where the climate is both mild and on the arid side, some reblooming irises will bloom a third or even fourth time! They can even flower on and off throughout the year!
In My Own Garden
I’ve planted several reblooming irises over the years, but none have ever rebloomed. I do realize I live in USDA Zone 3 (AgCan zone 4), where experts claim the chances of reblooming are slim, but I’m an eternal optimist. Each fall I therefore eagerly scour my gardens for any sign of off-season bloom and probably will until my dying day. I figure I might as well grow reblooming irises as one-offs, as I still get abundant spring bloom and have a slight chance of flowers in the fall. After all, nothing lost, nothing gained!
Some Varieties to Try
Here are some reblooming iris that are available, at least from perennial growers … but you’ll find many more if you dig through specialist iris catalogs.
Reblooming Iris x germanica ‘Champagne Elegance’. Source: David J. Stang, Wikimedia Commons
Iris x germanica ‘Mariposa Skies’. Source: Iris Wiki
Other Reblooming Iris
Reblooming Siberian iris ‘Ever Again’. Source: woottensplants.com
There are also reblooming irises in other categories, notably Siberian irises (I. sibirica) like ‘Ever Again’ and ‘Slightly Envious’, and Japanese irises (I. ensata) like ‘Purple Plus’ and ‘Triple Treat’, although they tend to bloom immediately after the first bloom or shortly thereafter, not in late summer or autumn.
Are you interested in reblooming irises? If so, you might want to join the Reblooming Iris Society.
Catalogs Offering Reblooming Irises
Here’s just a sample of many catalogs offering reblooming irises.
Remove rhizomes from the soil carefully with a garden fork and divide them with a sharp, clean knife so each new section has one to three leaf fans and healthy roots. Replant immediately. Most irises prefer well-draining soil in a sunny location. Your irises should produce more blooms the next year.
One may also ask, will iris bloom after transplanting? Transplanting: Irises can take several seasons to re-establish. New iris divisions may not be mature or large enough to bloom. Planting depth: The rhizomes should be planted so that the top surface is at or slightly below the soil. Irises planted too deeply will produce leaves but no flowers.
Additionally, how long does it take an iris to bloom?
They bloom just after Iris pumila in mid to late May and can last two-three weeks. 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.
What is the best fertilizer for irises?
Ideally, you should take a soil test to see which nutrients -- nitrogen, phosphorous and potassium -- you need, and fertilize accordingly. In the absence of a soil test, the North Carolina State University Extension recommends you use ½ pounds low-nitrogen fertilizer such as 5-10-10 per 50 square feet of iris bed.
Divide and conquer! Every three to five years Bearded Iris tend to become overcrowded and the rhizomes should be divided. You’ll not only get to add Bearded Irises to other parts of your garden free-of-charge, but you'll be proactively preventing the spread of pests and disease.
Bearded Iris should be divided and re-planted every few seasons to prevent overcrowding.
Basic Steps To Divide Bearded Iris:
'Speed Limit' Reblooming Bearded Iris captures the eye with its bold, deep-blue color. Its lower petals are each adorned with a pristine white spot directly in the center of each pet.