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Growing Irises

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Irises are beautiful colorful flowering perennials. This is a guide about growing irises.
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Ask a QuestionHere are the questions asked by community members. Read on to see the answers provided by the ThriftyFun community or ask a new question.

By 0 found this helpful
May 15, 2008

Question:

Does mowing your Irises after they've bloomed cause them to not bloom again the next year? I'm not much of a gardener, which is probably obvious. We've had them planted for several years, and they bloomed pretty well for the first 2-3 years. My husband then mowed over them the last couple of years (after their blooming season), and now very few have bloomed back. Is there anything we can do now to help?

Hardiness Zone: 7a

Leah from Shelbyville, TN

Answer:

Hi Leah,

Mowing them is fine after they are done blooming, but it is always best to wait until late in the season so the foliage has ample time to store nutrients for next year's bloom. Tell your hubby to hold off or even skip it this year and see if they come back strong next year. If not, then you need to look at other possible causes.

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When irises fail to bloom it is usually due to nutrient deficiencies, inappropriate watering, incorrect planting depth, or overcrowding. In your case, you mentioned that your irises bloomed well for the first 2-3 years, but have failed to come back strong since. Have you divided them in the past few years? In not, I suspect they are in need of some breathing room by now. After a period of 2-3 years, irises start to grow into clumps and become overcrowded. They won't bloom well again until you give them a bit of breathing room.

Another cause to consider is whether a few years of mowing over them have buried the rhizomes under a bit of lawn mower mulch. If these are bearded irises, they should be sitting in the soil so the tops of the rhizomes are at or only very slightly below the soil's surface. If planted too deeply, you will see foliage, but no flowers.

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Ellen

Answers

April 11, 20080 found this helpful

Mowing them should not damage them at all. Iris's are hardy. You may need to uncover the tubers however and pull some of them apart.
I am not a gardener but, I have Iris as they almost grow wild. The tubers seem to work there way out of the soil, so just brush the soil away. Look at the top bunch of tubers and see if they look eaten or mushy. Bugs will often times feed on the top bunch. Pull those off lightly. Then just cover the others up.
There always seems to be a lot more underneath and I get full blooms every year.

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April 12, 20080 found this helpful

If you are mowing down the tops, you are not allowing the tubers to "feed" and build up energy for the following year. The leaves are there to process the water and sun and feed the tuber, and if you cut them off, there is no food going in and eventually the tuber will just die back.

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April 12, 20080 found this helpful

We had iris that didn't bloom (maybe one or two would) but this was because the iris bulbs or tubers were VERY over crowded & needed to be thinned out... Are yours over crowded?

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April 12, 20080 found this helpful

I have tons of iris and I actually use the weedeater to take them down in the summer. Allow the leaves to stay a while after they bloom so they will get good "energy" to the tubers. The most improtant part of good blooming iris is that the tubers are exposed, I also live in TN so our weather is not so harsh. I always make sure that they are not too tight ( I actually just pull some out like carrots) then make sure that the tubers are not covered. When you first replant seperated iris you can take them down further so that they will set in but they eventually will rise up to the surface on their own just make sure you get all of the leaves and mulch off of them. If you do this you should see good blooms this year, mine bloom at varying times according to where they are in my yard. I have a lot blooming now but I will have another wave in the summer.

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April 14, 20080 found this helpful

I love iris !!
You may have them planted too deep.
Just barely put the risome in the soil......if there are those little "leg-like" pieces sticking out, put soil over those too. Leave the largest part of the risome just sitting on top of the soil.
If your husband is cutting over them, they could be sinking deeper than they need to be......covered by soil or even grass. Or by people walking on them.

They need those "green" tops ( leaves) to provide food for the risome after the bloom.This provides the food for next years blooms. By cutting those off, you won't get blooms next year.

Most folks cut the tall green leaves into a ^ shape, a Fan shape, or inverted V , in late July or August. Just use plain ole scissors to trim the leaves.This tidies up your flower bed. Yet there is enough green tops to provide the food necessary for next years blooms.

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After enjoying the blooms, cut off the tall stems that the blooms were on...try not to scalp it...leave it as long as the leaves are tall.
Try not to allow the iris to send up a large round "pod" looking thing on the stem following the blooming. This is called "going to seed." And it will take a lot of the nutrients from the mother plant.
Iris will grow in very poor soil. They don't require much attention. After establishing them, you will need to divide them in a couple of years. Share them with your friends ...most everybody likes iris.

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By guest (Guest Post)
April 15, 20080 found this helpful

When it happened to us, it was Iris Borers - a white grub that eats and destroys everything. We had to dig them up, destroy the borers we could find, sprinkle campfire ashes into the dirt before replanting them.

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May 15, 20080 found this helpful

I loosely braid my iris leaves and allow them to remain until they've done their job of storing energy for next season's blooms. I tie the ends off with strips made from leaf material. I do a few each day so it's not like I'm out there braiding leaves all day.

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Anonymous
May 15, 20080 found this helpful

Irisis are like tulips and daffodils and most bulb or tubular plants. They need the leaves to feed off of for next year's blooms. After they are done blooming just leave them alone for a month or 2 till they start looking dry,then cut them down with scissors to about 3 inches above the ground and they will do fine the next year. Also about every 3-4 years they should be seperated and thinned out. Good luck

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May 19, 20080 found this helpful

Just a note: Iris is toxic, so be careful what animals you feed those grass clippings to.

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May 20, 20080 found this helpful

My Dad ALWAYS mowed down the Irises. We would have to separate them every now and then. Then they wouldn't bloom too much the first year, but the second year they'd be fine. 45 years later I have some of those Irises from my parents house planted in my yard. Can't kill them!

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October 16, 2011

As you may know I'm starting a new iris bed in "The Path Garden". I saved this picture a few years ago and can't remember where I got it. Does anyone have this iris or know the name? I would love to have it added to the garden for next year. Thanks for any help ThriftyFun's family can provide.

By Great Granny Vi from Moorpark, CA

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By 0 found this helpful
October 30, 2008

Question:

Does anybody know why my irises didn't bloom very much this year? I had lots of foliage but very few blooms. We've only lived here a year and I can't remember what they did last year but this year I watched. I'm dividing them now (right or wrong?) so maybe they were crowded?

Hardiness Zone: 4a

Judi from Elgin, Oregon

Answer:

Judi,

Your assessment of the situation is probably right on the money. Irises grow in clumps. As they grow, they start to get crowded and their productivity declines. Dividing them every 2-3 years will easily solve this problem.

To divide your irises in the fall, cut the fans (leaves) back to 3 to 4 inches in length and use a sharp spade or shovel to separate them from each other so you can lift them out of the ground. When replanting, make sure you pick a sunny spot and that you plant the rhizomes so that the tops are exposed at the surface of the soil, or only slightly covered with soil. Water them in well.

Other factors that can affect how well your irises flower include the following:

  • Sunshine. To maximize flowering, your irises should receive at least 6 hours of full sun each day. Make sure that the trees and shrubs around your irises have not grown up to the point of blocking out their sunlight.

  • Fertilizer. A fertilizer high in nitrogen will stimulate vegetative growth at the expense of flowers. If you fertilize your irises, choose a fertilizer that is higher in phosphorus than nitrogen (e.g. 5-10-5)

  • Water. Too little in the late winter/early spring can adversely affect flower production. Watch moisture levels in the spring to ensure your irises are getting the moisture they need for proper development.

Ellen

Answers

July 10, 20080 found this helpful

Hi,

Iris do not like to be crowded, so dividing them is probably a good idea (not sure of timing for this myself). I do know that while the roots need to be deep, the rhizome needs to be near the surface. Below is a link that you might find useful for growing/planting iris.

http://www.irises.org/growing.htm

Good luck!
Joyce

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July 10, 20080 found this helpful

I also think that they may just be over-crowded. I also had a problem one time with white grubs eating the rhizomes, it weakens the plant and it won't bloom. I thinned them out, threw away any with grubs in them, or any soft rhizomes, and replanted them. Because they don't like to be set deep in the soil, they fall over a lot if there is too much foliage. I trimmed the green foliage back a little so that the plants would sit straight. They didn't all bloom the next year, but the following year they were great! Best wishes to you and happy gardening, Paula

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By guest (Guest Post)
July 10, 20080 found this helpful

I got some from my daughter 3 years ago and this year is the first time they bloomed. I was told by a master gardener that they must have 3-5 or 5-7 leaves before they will bloom. Don't give up on them. They will surprise you.

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By guest (Guest Post)
July 11, 20080 found this helpful

Most Iris beds bloom well only every other year, because once a Rhizome has bloomed, it makes an offshoot that takes another year to bloom.

When one plants a bed, they likely start with all similar sized Rhizomes, thus, there are no offshoots
to bloom well the next year, taking a year to set the blooms. I suggest planting younger with the old, or
dividing the Rhizomes more often, OR accepting the
fact that you'll likely only get more pretty blooms every other year.

In Texas, they take no care, preferring ordinary clay loam and a little mulch mixed in, less water, and nothing much other than removal of deal leaves, and dividing when over crowded. If any of the bases look holey, they likely have bugs and are the previous blooming plant making way for the offshoot to grow, also providing nutrients for it.

I have several dwarf varieties, and tall varieties, single colors, and bi-color and tricolors of about five or six variety colors in all, I forgot which.

One year, years ago, I drove the entire city looking for good varieties of Iris to request a start from the owner, all of whom were willing to share. I am the most pleased with the bi-color of the most brilliant yellow edged in white; then the tri-color, of course, in shades of apricot and pink. One I bought is nearly black, but has not bloomed nor multiplied as profusely because it is being overshadowed by a Boxwood and needs to be moved in the Fall. The plain whites are my least favorite, but the pale and dark lavenders are very fragrant.

Mine bloom for about three weeks a year, which I remove as each separate bloom fades, to encourage
it to continue making buds and blooming.

Hope this helps. Good luck and God bless. : )

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By guest (Guest Post)
July 11, 20080 found this helpful

Dividing them and when you replant, dig the hole and put a handful or so of Milorganite in the hole before the plant and you will be surprised how they bloom the next year! Also, don't plant them deep. They like to be just under the soil.

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July 11, 20080 found this helpful

As Joyce said, the rhizomes need to be close to the surface...even showing a little. Most people have a tendency to plant too deep.

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By 0 found this helpful
May 9, 2010

I have bearded iris in a raised bed. The last two years, I find as the iris bud comes up nice and tall, something is clipping the stem, snapping it off with a nice clean cut. I find the blossom on the ground. Are birds doing this? How can I prevent this from happening. Last year, I lost about half my blossoms this way.

Hardiness Zone: 5a

By Gary from Syracuse, NY

Answers

May 10, 20100 found this helpful

Today I found one of my stems just as you described, had some last year as well. I googled and all I could find that fit was a gopher, but I think it is an insect of some kind. I see no other signs of a gopher. An Iris borer was mentioned in the article I read but that didn't seem to fit either. Does anyone else have this problem, and what did you do about it?

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May 10, 20100 found this helpful

Most likely it is an animal of some sort not birds. Make a cover using chicken wire

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May 10, 20100 found this helpful

I don't know about iris blooms but I do know that baby deer used to bite off the blooms of my vegetable plants. They didn't eat them, just bit the blooms off and dropped them. Little rascals!!!

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By 0 found this helpful
July 1, 2015

Any suggestions on best way to grow irises and when, or if, you should cut them?

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By 0 found this helpful
June 29, 2013

This iris has done nothing for 6 months. It has started to grow 5 shoots a couple of weeks ago. 3 out to the sides and one is growing up. They are about 1/4 inch around and have a pointed tip.
Will one of these become a flower.?

By Bob g. from Toledo, OH

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By 0 found this helpful
July 30, 2009

What do I feed Irises? I've had these irises since we bought the house in 2002. I've divided them and replanted them in many locations. I was told to feed them Bone Meal in the fall (something I haven't done yet). Is this good for them and if so where do I get the bone meal? The color has faded over the years in the leaves. I think that's due to improper feeding, am I correct? I also want to re-do the flower bed where they are now. Can I dig them up now, fix the bed and replant them now?

Hardiness Zone: 8b

By tomarhoch from Tonopah, NV

Answers

August 1, 20090 found this helpful

Cut off dead blossoms and dead bloom stalks when the iris has stopped blossoming, but don't cut back the leaves until they begin to turn brown in the fall. The leaves are needed to produce next year's blooms. When you do cut, leave a fan shape about six inches long. Feed your irises a teaspoon of bone meal every fall and when you replant. You can feed again a month before they usually bloom if you like, but they are quite tolerant of just one feeding.get bone meal from Lowe's or where flowers are sold,I sug to move them after they bloom,for more info search for"how to grow irises",good luck.

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By 0 found this helpful
June 27, 2013

My iris last bloomed 6 mo. ago. I have been watering it and 2 weeks ago it started to grow tubers. 4 at the sides of the leaf base and one going straight up. Which of these if any might produce a bloom?

Please help, this was a trash can rescue last fall.

By Bob from Toledo, OH

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April 23, 20120 found this helpful

While the others are still not ready on that plant can I cut back just the top bloom and give it away?

By Jeff

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By 1 found this helpful
August 24, 2010

Should the ever-blooming iris be cut back at the same time as regular iris? If not, when should they be cut back?

Hardiness Zone: 7a

By Cathy from Williamsburg, VA

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Archives

ThriftyFun is one of the longest running frugal living communities on the Internet. These are archives of older discussions.

April 22, 20110 found this helpful

Garden: Irises

"Escape from Iris Island"! The flowers came up around our new airplane yard sculpture last spring without any real planning. As the season progressed and the flowers came into bloom, it was obvious this was exactly the best place we could have planted our "sculpture".

By Jim from Cleveland, OH

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March 22, 20110 found this helpful

This is a photo of my beautiful iris that I have planted in a container. I wasn't sure what color it was until it bloomed. It sure turned out pretty!

By One.of.a.kind

Bearded Iris (Rare Treat)

Bearded Iris (Rare Treat)

Answers:

Bearded Iris (Rare Treat)

Fabulous. We have a few, but they didn't do a whole lot this year. I think it takes a few years. (06/16/2010)

By Allison5

Bearded Iris (Rare Treat)

Anyone who features an iris gets my attention. My late dad used to raise them, divide bulbs, and share with friends in their church. He also would always have a large variety to put in their yearly "sale", adding funds for church activities. My folks lived on Camano Island, WA., And although they have both gone to be with the Lord, I miss them dearly.

Thanks for showing me a "picture" reminder of their lives. I have lived on the Gulf Coast for over 37 years now, and miss "home" to this day. Now we are looking at oil on our beaches, here in Theodore, AL. (06/23/2010)

By LJF

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August 24, 20100 found this helpful

My dwarf iris has finished blooming for the summer. The plant is a big sprawling mess. Can I cut it back now (June 12)?

Hardiness Zone: 5a

By Sally from Chicago, IL

Answers:

Cutting Back Iris After They Bloom

We can divide iris here in Southern Ca. during July/Aug into Sept. I haven't heard about "cutting them back". The normal thing is to dig up the rhizomes and cut the leaves into a fan shape, wash off the dirt and rinse the rhizomes in a 9 part water to1 part bleach solution. Let them dry/scar over for a few days before replanting. I assume that dwarf iris are treated in the same fashion. Good Luck. GG Vi (06/19/2010)

By Great Granny Vi

RE: Cutting Back Iris After They Bloom

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June 16, 20100 found this helpful


This Bearded Iris is called RARE TREAT.

By Great Granny Vi


Bearded iris, Iris germanica, is a hardy, long-lived perennial that require a minimum of maintenance. The flowers have six petals; three upright petals (called standards) and three hanging petals (called falls). A fuzzy line or beard runs down the middle of each fall. Flowers come in many colors including blue, pink, purple, reddish, white, yellow, and bi-colors. Most bearded iris flower in the spring (April to June depending on cultivar), but some of the new cultivars re-flower in the summer and fall. The second flower display is not as showy as the spring display but last into the fall. Many re-blooming iris are fragrant... Source: North Carolina Cooperative Extension Service

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June 15, 20100 found this helpful

What will happen to my irises if I cut them way back, leaves and all, now that they are done blooming?

Hardiness Zone: 4a

Ginny from New London, MN

Answers:

Cutting Back Iris After They Bloom

I was always told that the leaves need to stay on the plants and to just let them wither. That the rhizome gets "food" from the leaves and that if you do cut the leaves off that you won't get as many blooms the next year. I believe it to be the same with daffodils and tulips, that if you cut off the foliage the bulbs won't get enough food and you won't get many blooms the next year.

My sister-in-law mows her daffodils every summer and they always come back nice and green the next year, but with very little flowers. I don't want to take any chances, I like the flowers too much! (07/10/2008)

By Persnickety Paula

Cutting Back Iris After They Bloom

My sister has a day-lily business and she cuts the blades back called fans for shipment. It won't kill the plant, but may not produce next year depending on the size of the rhizome. This goes for irises as well.

I have irises in a permanent location and do not cut them back, but allow the leaves to die down and in the fall, clean up the dead blades. Always pick off the old blooms before going to seed so you can have more showy blossoms the following year.

Transplant extra rhizomes from the bed so you have space enough for growth when plants get too thick. (07/10/2008)

By Lorelei

Cutting Back Iris After They Bloom

In most hardiness zones (yours included), Irises need to be cut back in late July or early August. This is also the time to thin and transplant the plants. Cut the fans back to where they are about 5-6 inches tall. This allows the leaves to continue to feed the roots but makes your garden look neater. Remove any spent or damaged leaves.

If you are transplanting any of the corms (root tubers), make sure that you check them for iris borers. Borers will leave small holes in the corms where they eat their way into the corm. Dispose of infected corms in the garbage, not your compost bin.

When dividing corms, cut the small "daughter" tubers away from the "mother" tuber with a sharp knife. Transplant into shallow trenches. Spread the roots out and cover lightly with soil. Irises do not like to be buried too deeply, they will not bloom if the corms are covered with too much dirt.

I hope this information helps. I've been doing this for twenty years, and I have a garden full of irises. So do my friends and neighbors to whom I have passed along plants over the years. Good luck and happy gardening! (07/11/2008)

By readingiggits

Cutting Back Iris After They Bloom

Wait till the foliage dies, then cut them back. (07/12/2008)

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February 2, 20100 found this helpful

These are irises at our mail box. I'm very proud of them.

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