Ask the Expert: Why wont my Iris bloom?
My Iris’ get great green leaves but I fail to get a bud, which in turn I don’t get a bloom?
Mary Ann
Iris Refuses To Bloom – A Deep Resentment.
May 6, 2008 by
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Mary Ann,
There are many reasons iris won’t bloom. There are also many types of iris. Since you didn’t mention which type of iris you have, I am going address this question as a bearded iris issue.
The two most common reasons that bearded iris won’t bloom are: buried too deep and not enough light. The iris rhizome should not be covered with soil and should not have much mulch, if any, on top of it. When the rhizome is covered it will produce lush green foliage and no blooms. Bearded iris need a minimum of six hours of direct sun a day to bloom well. Start with these two reasons and see if either one is the reason your iris won’t bloom.
Other factors including improper watering, insufficient phosphorus and too much nitrogen, overcrowding and late freezes can also inhibit blooming. Check your conditions and see if you can determine the cause. Please let me know if you need more information.
If I re-plant my iris, since I believe some of mine are also buried too deeply… does that mean they won’t bloom next year? I’ve always heard that Iris won’t bloom the year after you plant them (or move them…)
Thanks for any info…it’s quite frustrating as I’ve “rescued” Iris from old homesteads and also bought very expensive rizomes from Iris Farms and still don’t see too many blooms each season…
Toni,
I have heard the same thing. However, it has never been a problem for me or for my mother. Who by the way moved her iris at a very inappropriate time. If your iris are buried too deep they are probably;y not going to bloom any way so what have you got to lose. I would also recommend fertilizing your iris. When planting bearded iris top dress with a low nitrogen fertilizer and in the spring each year top dress with a low nitrogen fertilizer.
I planted German iris bulbs this spring the folage is beautiful green and healthy, I also bought bone meal to help fertilize them and still no blooms..they were suppose to continue to bloom all summer. Tried everything can you help.
When you planted them did you cover the rhizome with soil? If so they are planted too deep and will need to be raised. Are they getting enough sunlight. They need at least 6 hours a day.
Sometimes Iris have a blooming issue the year they are planted which keeps them from blooming. In cases such as this there really isn’t anything you can do. However, I would make sure that they have all the right conditions to bloom next year. Give them a bulb fertilizer in early spring (a 7-8-5 formula or similar) and then again at the beginning of summer. Make sure the rhizome isn’t too deep and you get adequate sun. You might also try a small amount of super phosphate on them in late winter.
I transplanted iris 4 or 5 years ago they have done great, until this spring. No blooms, not a single shoot. I\’m not sure what has happened.
Mary Jo,
If you use mulch in your iris bed, you may need to lift them up. the mulch can act like soil and make the iris think they are buried too deep.
My Iris develop buds or what look like buds but there is nothing in them so they don’t bloom. What is the cause?
Mary,
What kind of Iris do you have? It could be that your irises may need to be divided. If irises are left undivided, flowering decreases, and the rhizomes become subject to pests and damage.
My bearded Irises have the same problem–no bloom. Most are over 5 years old. A very few bloomed last year(out of many) I have followed all the directions above for years and no help. Only thing I havent done is use the superphosphate. Should I throw them all out, or is there a chance that the superphoshate will make a difference? If so, what dose?
Judith,
Lack of blooming in bearded iris is often a result of the iris rhizomes being planted too deep. As the year goes by, soil, mulch and other debris accumulate on top of the rhizomes. You need to dig the iris up and re-plant them so that the top of the rhizome doe not have any soil on top of it. This would also be the time to thin out the bed. Too many rhizomes plant too close together can also inhibit blooming. Try replanting them and if the blooms are still lacking add phosphate and make sure the iris are getting minimum of 6 hours sun a day.
Good Evening,
I live in a tropical area where the average temperature is 30 degrees Celsius. I planted some German irises and they growing beautifully. Some of them are blooming nicely. I would like to know if it is true that I have to refrigerate those irises for a certain period for them to bloom again?
Thanks in advance for your answer.
Regards,
Flavia
Faya,
It’s not necessary unless you really want them to bloom at a specific time.
Thanks a lot for the info. I appreciate it.
I’ve been disappointed in my iris for about 3 years. They used to bloom prolifically, especially 4 years ago, which was the first time I composted them. I just learned nitrogen fertilizer will keep them from blooming. No problem. I don’t fertilize them. But –I’ve just learned–my husband started putting bone meal on them, yep, 3 years ago. He also started putting a nitrogen booster in the compost pile. Are my iris dying or just damaged? Can I save them by watering or mulching with a light wood, as one site suggested? I’m sick with grief (no I’ve haven’t killed my husband — yet!)
MaRica
Sounds more like the iris are planted to deep. Iris rhizomes like to be very close to the top if the soil. Too much c9mpost or mulch on top of an iris will keep the iris from blooming. Reset the iris by digging them up and replanting them with only a small amount of soil on top. Hopefully your husband can help you.
I bought some iris several years ago from an iris farm. When I bought them the old man dug them up and told me not to separate them before I planted them but I did because I had done it before and now they are not blooming did I not leave enough of the root to separate them or why else would they not be blooming I don’t believe I buried them too deep…
Well, after reading everything, one problem is they’re really crowded but I have no idea where I’d put them. How much water would they need?? I do have a very exposed area along a west facing fence that has a drip line for the grasses I have there so drips could be added. Second issue is I had very few blooms in the overcrowded bed last year (not quite enough sustained sun, I think) but I have loads of well-developed buds this year. The problem is they seem to be drying out without blooming. Staring at them and begging isn’t helping. I’m hoping somebody out there can. Thanks!!
Hi Pam,
The two most common reasons that bearded iris won’t bloom are: buried too deep and not enough light. The iris rhizome should not be covered with soil and should not have much mulch, if any, on top of it. When the rhizome is covered it will produce lush green foliage and no blooms. Bearded iris need a minimum of six hours of direct sun a day to bloom well. Start with these two reasons and see if either one is the reason your iris won’t bloom.
Other factors including improper watering, insufficient phosphorus and too much nitrogen, overcrowding and late freezes can also inhibit blooming. Check your conditions and see if you can determine the cause. Please let me know if you need more information.
Linda,
Iris need at least half a day of sun. So planting on a west facing fence should be a good spot. As for watering, normal rain fall depending on where you live should suffice. Since I live in Arkansas and our summers can be dry, I water mine about once a week for two to five minutes with my sprinkler system. Now to address the dry buds. Two things can cause dry buds – 1) not enough moisture at bloom formation 2) aphids attacking the plant. I suggest checking the blooms for aphids. You can spray them with an insecticide is the plants have aphids. Hope this information helps.
Jamie:
I live in Oregon, about 5000 feet altitude. I think the location I’m thinking about would work but my only major concern is the wind. It regularly hits 20-25 mph with higher gusts and the location takes the full brunt of it. I checked for aphids like you suggested and didn’t see any. I’m having trouble with my sprinkler system so they haven’t been getting their usual amount of water. I’ve pulled out the hose and sprayed them for the last week or so (my guy has been busy and hasn’t been able to do the work but it’s gotten old so I may need to get somebody else in before my lawn goes south) and it seems to have helped. They’re so pretty at the moment I want to show them off so I took pictures but it doesn’t appear I can attach them. Anyway, thanks VERY much for your help!! Linda
Some of my iris are getting what appears to be seed pods on some of the blooming stems.
Once the bloom is gone I usually trim just the stem back. Should I leave it alone if it has these pods
(and what are they )
thank you
Erin,
Iris do produce seed pods. You can leave the seed pods on the stalk until they open and drop the seeds in your iris bed. The seeds may or may not germinate the next year. Or you can harvest the seed pods as they open.
One caveat about iris from seed: they may not (probably won’t) come true to the mother plant, especially in the case of most hybrids. This is particularly true with the bearded varieties. Most of these have been so hybridized as to be well removed from any “wild” stock. This isn’t to say that you “absolutely cannot” grow an iris from a seed. You can do it if everything’s to their liking, and you might well end up with a lovely iris for your trouble, but the chances are quite high that they won’t look anything like the mom. If you absolutely love a particular iris in your garden and just have to have more of them– you’re best off going with rhizome divisions. These are clones, and they do come true. But if you just want to see what pops up from seed, go for it– you may be pleasantly surprised or utterly horrified. That’s the fun of iris breeding, ha ha!
When you say don’t cover the rhizome, what do you mean by that? I’m literal. my irises , bearded, came with the house. Only one or two will bloom. I’ve been told that irises only bloom every 2 years. I moved them to a sunnier location and about 1-2″ deep, as I was told. So should I redig them and just leave them exposed? covered lightly? mulch? what type of mulch? Do I furtilze them? with what? I live in foothills of North Carolina.
The rhizome should be partially covered with the top part exposed. You do not want to mulch around the rhizome. Depending on the age of the irises, you may need to divide them. Make sure they are planted in a sunny location with good drainage. Use a well-balanced fertilizer with nitrogen, phosphorus, and potash. Your local nursery can help you choose the one that will be best for your area.
I live in Florida and have a walking apostle iris that bloomed last year and then formed another one over the winter. This Spring, the mother plant is not blooming. What could be the problem?
I grow all Historic Iris, in 2 gardens. Many did not bloom the first season after planting in the fall.
This will be the 2nd year, and I am hoping that they bloom. Many have told me that some Iris
do infact take 2 seasons before they will bloom. Has anyone else experienced this ?
I had a beautiful patch of bearded irises. Finally three summers ago when there were about 50 blooms I waited until fall and divided them and transplanted them. I left the rhizome showing. They are facing west. Each one is atleast 18 inches from the other. Last summer they did not bloom but I did not worry. This winter was mild here in Indiana and the old leaves never died. I had cut the leaves down to 4 or 5 inches. This summer I expected them to bloom but only have two buds. Can you tell me what to do? It’s been two summers now and I miss my beautiful purple and white bearded irises. I planted about forty rhizomes of different sizes. They have tall green leaves but only two buds on one plant. Help?
How long do dried rhizomes take to rehydrate? I planted some over a month ago, but not seeing any shoots at all.
Hi Larisa,
Do you know if you bulbs were prechilled before you planted them? Depending on which type of bulbs you have planted, they need around 12-15 weeks of cold weather before they begin to bloom in the spring. Normally you plant spring bulbs in the fall, however, if you purchased your bulbs from a nursery, they were probably prechilled. I would pull some of the soil back and check them for signs of root growth. You also want to make sure you haven’t planted them too deep. Iris bulbs only need to be a few inches in the ground, with the top of the bulb exposed.
Hi Jennifer,
Are your irises getting enough sunlight? They need about 6 hours a day. There is a possibility the bulbs did not have the opportunity to chill long enough if the winter was very mild. Irises need 12-15 weeks of 35-45 degree weather to help them bloom in the spring. You may also try fertilizing your irises with a low nitrogen fertilizer to see if this will help perk them up.
Hey Patrick,
While I have not experienced this personally, I have heard from many others that they have had this occur with their Iris.
After speaking to other Irisarians who grow Historic Iris, it appears that Yes, Historics are noted for taking 2 if not 3 years before they settle in and bloom.
Hi Jean,
In most cases, the mother plant will not come back, but that also means that the child plant will continue to grow and produce flowers. If you want more blooms, what you will need to do is dig up the iris, divide the mother plant from the child plant and any other child plants, and then replant the child plant/plants after you have divided them. You will need to wait to do this after it is done blooming.
Can I divide the mother plant since it is very healthy looking?
Hi Jean,
Mother plants can, and should, be divided, but you’ll want to wait until late summer before doing so.
Thank you for your help.
Two years ago, my bearded iris were beautiful!! Last year, not so much and this year they did not bloom at all!!! They have plenty of sunshine and this year I knelt down and pulled off all of the top soil that had washed over the bulbs (large area with lots of bulbs). What could be the trouble?? Some may be deeper than others, but shouldn’t Thankssome of them have bloomed??
Tell me what I can do – would appreciate any suggestions.
Hi Elisabeth,
As iris get older, they will start to produce less. You may want to divide your irises. If you have several, you will want to make sure they are not planted too closely together, as overcrowding can also cause poor blooming. If you have not fertilized them in awhile, try fertilizing as well.
I purchased bearded Iris several years ago and they have never bloomed except for 2 or 3 of them. I understand they may be buried to deep. Is here a better time to dig them up? It is almost June in Delaware, it starts getting very hot and the rains stop. Should I wait until fall or doesn’t it matter. Also should they be planted by themselves or can other flowers such as bee balm or coneflowers be planted with them.
Hi Karen,
If your Irises are several years old, it may be time to divide them. Also, if you want to try lifting your bulbs, or uncovering the tops of them, they should by fine. If you decide to divide them, wait until mid to late summer. You can also try adding a low nitrogen fertilizer. As far as companion plants for your Irises, you do not want to overcrowd the Iris bed and want to make sure any plants you put with them will not grow taller than the Irises.
If you have had bearded Iris in the ground for ‘several years’ and they have not bloom …. there is a problem. Bearded iris are ‘rhizomes’ not bulbs. There is no point in dividing them if they have never bloomed. The longest I have waited for my Iris to bloom is 2 seasons. No longer. Where did you obtain the Iris rhizomes ?
Thank you for your information.
Thanks everyone for the comments on Irises. I’ve been digging and separating for 2 day…I’m tired !
Hello everyone! Great comments. I read them all and didn’t find an answer to my problem, however. I’ve grown bearded Iris for a long time and they are still blooming beautifully.
My problem is the Dutch Iris. I had them where I lived for about 15 years and they bloomed all the time. When I moved, I gave them to my daughter as I was living in an RV until we found a house. They bloomed great for her, as well. After “settling in” for about 8 years (I was supposed to get them after about a year, but yeah, that didn’t happen! lol!!) So she dug a bunch up and gave them to me. I planted them and took care of them as I always had. They bloomed so beautifully the first year and now – 2 years later – nothing. na-da. zip. not a single bloom. All I can find is info on bearded Iris.
Does anyone know what they want? They get plenty of sun and are watered the right amount. I live in Oregon and the bearded iris are doing great. So are the Daylilies – both are plants my daughter dug up and gave me at the same time as the Dutch Iris.
HELP! and thanks!
Hey Teri,
You may want to try dividing your bulbs. Also, have you tried fertilizing them?
I also have non-blooming bearded iris in several heights… tall, intermediate, dwarf, etc. Many are Dykes winners or at least Honorable Mention,They definitely are not buried too deeply as I can see the “scaly” or “barky” part of the rhizome. They are literally just at the surface of the soil. I tried triple phos and everything that is known to help blooming. They aren’t at all crowded, and were divided in 201 after no blooms in 2014 or 2015. I hoped for some flowers in 2016… not a thing. I hoped that they just needed to re-settle and that they’d flower this year. Nope, nothing but one lonely ‘Surf Lady’, a couple of ‘Chasing Rainbows’, a couple of unknown purple dwarf (those WERE crowded– I divided them after the bloom) and a few ‘Persian Berry’ (2015 or 2016 addition to the group so still new). I’m not in borer territory– as far as I know, we don’t have iris borers here like we did in Illinois). I have seen NO pests, but I did a general treatment “just in case”. They are in full sun from dawn to dusk. I’ve fertilized. Drainage is perfect. Fans are perfect and they do increase (make more and more fans), so yes, I divided just because they were starting to crowd. I have GORGEOUS green leaves– they do everything except BLOOM.
The only thing I can think of is our extremely mild recent winters screwing up their “sleep cycle”. See, I’m in Dallas, TX and we haven’t had much winter for the past few years. Oddly, though, we are now in late July and have hit 100 degrees… and on a recent 100 degree day this week, I spotted ONE lonely iris flower… just one, buff color (I have a lot of those), an unknown variety that even my Irisarian friend hasn’t been able to ID for sure. It is certainly a very lovely variety. I also had a couple of dwarf purple that bloomed at Christmas (WHAT??!!). So it’s not that I actually get NO blooms– just a random bloom, maybe one flower, totally out of season and completely unexpectedly… or maybe one flower at a time when I have hundreds of plants.
Does this sound like a weather issue that might resolve if and when we get back to our usual climate pattern with an actual winter and cold temps and adequate but not TOO much rain in the correct months? (Here, it’s either flood or drought, not much in between!)
I think you are correct in your thinking that the abnormal weather is causing havoc with your irises. If the winters have been unusually warm, your rhizomes probably haven’t been able to enter their dormant period. You may also try to increase watering if you haven’t already done so. Just be careful, because you don’t want them to stay too wet. Since it has been a couple of years since you last divided them, you may want to check again for overcrowding.
Well, here it is– another spring, and no flowers– not even an oddly timed one. We had a normal winter, I increased watering, we had good rain… I still have no flowers. I divided, though they really weren’t all that crowded. I fed a good phosphorus fertilizer. Same thing: plenty of leaves but no flowers
I give up. I’ve pulled every single one out and tossed them into the mulcher.