Dividing Iris's

Hi I have some bearded iris's that didn't bloom very well this year. This was their second year and was beautiful the first year. Do they need divided and how to I do it? When should I do it? Thanks for any and all help!

 

Bearded iris - gorgeous. Let's see what we can do. Bearded iris can usually be left in place 3-5 years before needing dividing. I will deal with cultural problems you need to check on first for why they did not bloom well the second year. Compare the below directions for planting/transplanting with your plants current situation.

1. Test for acidity, adding lime if needed to bring the pH close to 7.0.

2. Must have good drainage. They will not tolerate wet soil.

3. At least half day sun, preferably full day.

4. Soil prep: Dig a hole about 18" wide and 12" deep. Amend soil with compost and bone meal.

5. In 3 - 5 years the centers of the plant will have lost vigor. Get new plants from the perimeter. Dig entire clump, shake off soil, cut foliage back by about 1/2 its length to accomodate root loss. Do not cut back more than that as this is what feeds the roots.

6. The best divisions are Y-shaped fans known as double fans. These are two small rhizome knobs with leaves growing from a larger one. Single fans will also develop into good plants but will just take a little longer. Use a sharp knife to sever the larger rhizome section at the joint.

Examine each plant for disease and borers. Cut away any found. If this is a problem in your area you can dip the roots in a 1 part chlorine bleach to 10 parts water solution when dividing them. You can also plant so the top of the rhizome is visible to prevent rot and maggots. Remove any diseased foliage throughout the growing season.

&. Plant 6" to 8" apart (if planting a row) or set three together in a triangle. No closer together in the center than 2" with the leaf end pointed outward. Spread out the feeder roots so they aren't crushed . The feeder roots should hang down. Cover with no more than 1" to 2" of soil. As they become established rain and irrigation will wash some of this soil away and the rhizomes will seek their own depth.

Ph neutral, good drainage, sun, compost, and bone meal describes their needs.

Maintenance:

1. Dividing is done around June because the plants rest then after bloom and are less stressed by being dug and cut. Late blooming iris can be done in July. Just follow the above.

2. Remove all spent blossoms. Cut bloom stalk down by half when bloom is over.

3. When leaves begin to die and droop, usually during July remove them. If allowed to stay they will cut off sun from the rhizomes. Do not cut off until obviously wilted. Do NOT cut down all leaves after bloom. The plants rhizomes get their nourishment from the leaves.

4. Do not allow other plants to crowd. Bearded iris need all the sun they can get.

5. In early spring (around March) give the bed a surface dressing of equal parts lime (if acid soil) and bone meal. Rain and irrigation will work it down into the soil.

Boy, ask a simple question and get a treatise on iris. Sorry about that. Hopefully the above will get you back to having beautiful flowers.

Best - Ladybug

 

Thanks Ladybug, so much for all the info! I can use all of the things you told me and learned alot too...I have one other question, I forgot to ask. You mention deadheading the flowers and cutting back the leaves.. well I always deadhead the spent flowers but my leaves never die back...some have turned brown at the base and I have some tips that are brown but they never really wilt or die back..so should I go ahead and cut the leaves back part way even if they don't die back? And should I do it now? Maybe this is part of what the problem is of why they haven't bloomed very well this year..the rhizomes may have been shaded by the leaves as you said. Thanks again!

 

As long as the leaves are healthy looking, no, don't cut them back. I do have some questions for you:

1. What part of the country do you live in?

2. Where the leaves turn brown at the base is the brown area soft, mushy, or slimey or is it dry, crisp, papery feeling with healthy green growth above?

3. How far up the leaf does the brown area extend?

4. Since these plants are 2 yrs. old do the rhizomes still have soil covering the tops of them.

5. What fertilizer(s) have you used?

6. Being VERY CAREFUL not to injure, scratch, or bruise the rhizome does it feel soft?

7. Are there any discolorations of the rhizomes or sections of the planting that have shut down or seem to be dying out?

8. How much sun do they get?

 

Hi Ladybug,
We live in middle Georgia. The brown leaves are at the very bottom of the leaves and are dry and do not extend up plant. The rhizomes still have some dirt covering them and do not seem soft. The very top tips have been browning(to down a couple inches) also but I just figwred that was due to our lack of rain and watering restrictions during the hot months this year.
I beleive they get atleast the required amount of sun and in fact some are blooming now but not like that did last year. The stems of the flowers are shorter and all are the same color that are blooming now. Thanks again for your help.

 

Hi catzcar,

The leaves are fine ditto rhizomes. You're right - the brown tips are probably just from the heat and water restrictions. Since the plants like it on the dry side that is alright.

When you say the stems are shorter that makes me think it is a lack of nutrient problem. Try the bone meal in the spring and again the following year. Just apply according to package directions to the soil around the plants. See if that makes a difference.

Also check the pH of your soil and apply lime if necessary per the above.

I think that will do it.

Best - Ladybug

 

Just wanted to Thank you again Ladybug for all the info and help with my Iris's!
It's so appreciated!