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Iris

January 9, 2016

QuestionA friend gave me some plants and told me they were Louisiana water irises. In a public place I saw the same exact plants with the same exact flowers and the identifying plate said they were Southern Blue Flag Irises. The Southern Blue Flags bloomed in the spring but they also bloomed in November-December. My irises only bloomed in the spring. Are these the same irises? And could the Southern Blue Flags of be a hybrid, because they did bloom again in the autumn. I think they bloomed that late because it has been so warm.

 

Answer

 There are a lot of different types of iris out there and iris growers are constantly coming up with new hybrids. Most fall into the bearded or non-bearded type.  Louisiana iris are native to the American Gulf Coast and are non-bearded; they require soil that is somewhat acid and wet in the spring. The blooms are usually very wide petaled and open, showing brightly colored style-arms and sharp signal-crests.  They come in a wide array of colors, including blue, but also reds, pinks, whites, etc.  Another group of non-bearded water loving iris include the Japanese iris.  They are typically the last of the iris to bloom and require a slightly acid soil. Blooms are usually huge, ruffled and flat in form; some are marbled with gray or white.  Flag is a common name given to many different types of iris. And while there is a whole host of reblooming iris out there, I think many plants were confused this December with the mild weather. I saw numerous irises blooming along with some daylilies, azaleas, and other spring bloomers.  Winter appears to be with us now, so maybe plants will go back into dormancy. 


 

(May 2010)

QuestionMy mom has the most incredible iris bed.  She started out with many gorgeous colors but now they have all turned blue.  Is this due to her soil?  Is there anything that can be done to bring out the original color of these  iris?

 

AnswerIris colors will not change based on soil pH like hydrangeas will.  What often happens is that one cultivar is tougher than the others and eventually takes over a bed.  Then the resulting color is all the dominant plants.  She can thin out the bed and replace with some of the other colors and they should be fine.

QuestionI want to move some Iris's that are blooming now.  I want to know if I move them now, will they bloom next spring.  If not, when is the best time to move them?  I would like to move them while they are blooming so that I am sure what I am moving.

 

AnswerThe best time to move iris is six to eight weeks after they bloom.  Division and transplanting can be done at the same time.  I would try to flag them now with some type of marking system while in bloom so that you know what you are moving later.  If you move them too soon after bloom or during bloom, they won't die, but they may not bloom as well the next season, since they will be busy getting re-established and may not set flower buds.   Moving them after they set their flower buds should ensure good flowering again next season.


(May 2008

QuestionShould you cut back iris after they have finished blooming?

 

AnswerIris plants may be cut back six to eight weeks following bloom if you choose to do so. It is not a requirement, and we never cut the foliage off completely—they can be pruned into a fan shape.  Iris growers who have hundreds of plants often choose to cut back to the fan shape to allow for better air circulation and sunlight penetration, to help prevent diseases.  If you just have a few plants, pruning back is not necessary, but may be done if you so choose.


(October 2008)

QuestionI recently moved to a new house and the former owner had many beds with a wide variety of plants. I am cleaning the beds now.  Do I cut the calla lilies down to the ground? How about the irises?  I will be moving a lot of them to new locations.  What is the best way to do that? I also have peonies that have many brown leaves; can I trim and/or move them?

 

AnswerCalla lilies have beautiful foliage, even when the plants are not in bloom.  If the foliage still is green and healthy looking, let it grow as it is adding interest to the garden.   Once it begins its decline, or after a killing frost, cut the old foliage off.  Bearded iris foliage is evergreen most winters, so leave it alone.  Peonies can be cut back as soon as the foliage begins to brown.  They start their growing season early, and often go dormant early in the fall.  Dig and divide your peonies now if needed.  Make sure you replant them shallowly.  Iris are best dug and divided six to eight weeks after bloom.  Doing so in the fall leaves them little time to re-establish their roots before it gets cold.  Bearded iris rhizomes are planted with half of the rhizome or bulb in the ground and half above ground and if they lack a strong root system can get heaved out of the ground during the winter months.  For calla lilies, leave them alone until them begin to emerge next spring.  They are not reliably winter hardy in the northern tier of the state, so extra mulch is great for added winter hardiness.


(Dec. 2009)

QuestionAbout two weeks ago I planted Dutch iris bulbs and muscari bulbs in big pots. They are coming up now, so I won't have them in the spring like I had planned. Is there something I can do to protect and prolong their growth?  Should I have waited to plant them after a frost?

 

AnswerIt is not unusual to see bulb foliage up this time of year, particularly grape hyacinth or muscari bulbs.  They start growing in the fall every year and still have spring blooms.  Add a little extra mulch around them but don’t worry. They are cold tolerant.  As for the Dutch iris, I am surprised they sprouted that fast, but you should just have foliage and no flower buds yet, so again, you should still have spring blooms.


(June 2006)

QuestionWe always find your advice helpful. I would like to cut my iris foliage into a fan shape. However, I've been told that irises rhizomes need to feed on the foliage. We live in Jonesboro and would appreciate your advice

 

AnswerMany iris growers do cut the foliage back into a fan shape six to eight weeks after they bloom. Cutting them back prior to that time period can actually impact their flowers for next season, as reduced foliage produces less photosynthesis, and thus less food for the rhizome. Cutting the foliage into the fan shape has become a common practice for folks who have many iris plants in the garden. Cutting the foliage increases air flow and can reduce the chance for disease problems. If you only have a few iris plants in your flower beds, cutting the foliage is not necessary, it simply becomes a matter of aesthetics--and which you prefer. I think the full foliage blends in my beds more easily, while others like the cut look. Regardless of whether you cut or not, be sure to give them a full eight weeks of growth after bloom before cutting


(April 2005)

QuestionI want to grow irises in my garden up here on the mountain, and a friend divided his and brought some up.  They were all clumped together and some of the root system was soggy.  I found a website that told me to cut those soggy roots, divide, and cut the foliage.  I planted them in a nice bed of soil and humus. The rhizomes are under the soil.  The irises don't seem to be faring well, though, and they get full sun.  Is it the temps?  Or should I replant the rhizomes partially above ground?   Or should I start over, or forget growing irises up here?  I know they will grow up here, though, because an old homestead is covered with them.

 

AnswerIris rhizomes need to be planted half in the ground, and half out.  They need a well drained soil, as they rot easily.  Don't mulch them either.  Hopefully they can still be salvaged. They can be easy to grow if they are planted properly and in a well-drained site.


(January 2006)

QuestionI spent the summer preparing a 30 x 55 foot 3 season perennial flower bed. I have two questions that none of my books answer fully. First, do you recommend a pre-emergence herbicide and if so which one. Also, I've been told that you can actually double your bed color by planting - example, summer blooming oriental poppies between your spring irises?

 

AnswerI usually don't use any herbicides in my flower beds.  Right now, keep it weeded with a hoe and then mulch after planting.  The main summer weed is grass which is not prevented by a pre-emergent herbicide.  I usually have more problems with broadleaf winter weeds, which it is too late to use now anyway.  Plus, be aware that pre-emergent herbicides can impact any flower seeds you may be planting.  Double planting--or close spacing of spring ephemerals or short-lived cool season plants can work, but make sure you allow ample room for their root systems to grow and to become a mature size.  Bearded iris doesn’t like competition, but spring bulbs can be interplanted around many perennials.


QuestionI want to grow irises in my garden up here on the mountain, and a friend divided his and brought some up.  They were all clumped together and some of the root system was soggy.  I found a website that told me to cut those soggy roots, divide, and cut the foliage.  I planted them in a nice bed of soil and humus. The rhizomes are under the soil.  The irises don't seem to be faring well, though, and they get full sun.  Is it the temps?  Or should I replant the rhizomes partially above ground?   Or should I start over, or forget growing irises up here?  I know they will grow up here, though, because an old homestead is covered with them.

 AnswerIris rhizomes need to be planted half in the ground, and half out.  They need a well drained soil, as they rot easily.  Don't mulch them either.  Hopefully they can still be salvaged. They can be easy to grow if they are planted properly and in a well-drained site.

 

QuestionWhat can I spray in my iris bed to get the grass out? What can I use in other flower beds to control grass and/or weeds ? How do I determine what it can''t be sprayed on?

 

AnswerYou can spray a grass specific herbicide such as Vantage, Grass-b-gone, Ornamec or etc. This should be used earlier in the season as the grasses begin establishing themselves. While these products do come with a list of plants that have been tested for their use, there is no way they could test the product on every ornamental plant available. therefore, for any plants not listed on the label, do a small test plot first, before randomly applying it.


 

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