First, let’s be clear: we are referring to Bearded Iris in this discussion. The myriad of other lovely Iris varieties come with their own set of operating instructions.
Our last two blog posts generated a number of very worthwhile questions. After doing a bit of reading on the subject, I came across a couple of useful bits of information. The first is a series of photos on planting Bearded Iris, see below. These come from William Shear’s, “The Gardener’s Iris Book” (Taunton Press, 1998), page 43. How deep should the rhizome be? We are in agreement with Mr. Shear on this question. “It depends,” he writes. “In light-textured soils, it can be covered by as much as 1 (one) inch of soil, but for average to heavier soils, the top of the rhizome is best left exposed to the healthful influences of sun and air. Remember that the rhizome is a stem, not a root, and needs to breathe!” You can see in the third photo below that the top of the rhizome is still peeking through the soil.
On the subject of trimming the foliage, I found a bit of tidy wisdom, the kind you keep clipped into your pocketbook, or saved on our phone, for easy reference. This comes from, “A Guide to Bearded Irises: Cultivating the Rainbow”, by Kelly Norris (Timber Press, 2012). In his myth-busting section he addresses the question of trimming. “Myth: Bearded irises are so much work. You have to trim the foliage back every summer!” Mr. Norris reassures us that in fact this may be an “unnecessary chore”. There is no real need to trim the foliage in the summer, except that during dividing and transplanting shorter foliage eases the handling of the plants. He reminds readers that “needlessly trimming the foliage back in the middle of the season actually breaks an iris’s dormancy, kick-starting foliar production. This can take away from root mass accumulation and even from reserves meant to support flowering the next spring.”
The long and short of it is to plant shallow and leave the leaves alone. Thanks for reading and happy gardening!
July 23, 2017 at 1:50 pm
I have ordered Iris plants from you. I am in zone 9 and we have hot summers
July 24, 2017 at 8:31 am
Thank you for the comment and for choosing Schreiner’s Iris Gardens!
July 22, 2017 at 8:52 am
These articles are a great help. I didn’t know much about them and now I nay have better luck with bloom..thank you.
July 24, 2017 at 8:31 am
Thank you for the message! We are happy to know that our blog provides useful information to our readers. Feel free to contact us should you have any further questions. Kind regards!
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September 3, 2015 at 3:29 pm
I had some breathtaking bearded Iris bloom this year. I thoroughly enjoyed every moment they bloomed; however, after blooming all the foliage died back and totally disappeared!! The soil they are planted in is not wet but well drained. Will the loss of foliage prevent my bloom next year?
Thank you so very much for your opinion.
Laura C Kingston, TN
September 4, 2015 at 8:07 am
Hello. Thank you for the comment. It is normal and natural for the foliage to die back during the summer. However, it is uncommon for the foliage to disappear completely. The foliage collects the sun’s energy during the summer months, feeding the rhizomes in their growth cycle. You may see a lack of or decrease in bloom next spring. If the rhizomes are still firm, not rotted, and putting out new growth, then there might be a chance for bloom next year. Remember that Bearded Iris do not need a lot of water. If you are in a dry spell in your area, you may water the Iris once every 10 days to two weeks. If the Iris survive the winter, you should see foliage begin to shoot up in the spring. When the tulips begin blooming in your neighborhood, apply a low-nitrogen fertilizer (5-10–10 or 6-10-10) to your Iris (per the manufacturer’s instructions). Let us know how things turn out. Another word of caution: avoid applying weed-killers such as “Round Up” or “Caseron” near the Iris. This can kill the foliage and the plant.
September 4, 2015 at 9:50 am
I tried to reply to your answering my question…..hopefully you can retrieve it and answer this question?
Since all my foliage has all died out….completely gone…..do I need to dig them all up, enhance the soil and replant them ? I want them to be as pretty next year as they were this year because they were so pretty and I enjoyed them so much.
September 4, 2015 at 10:09 am
This is a good time of year to transplant. You want to be sure to get them back in the ground six weeks before the first hard frost, though. You can amend the soil with nutritious organic matter. Be sure to maintain good drainage. Plant them in full sun. Plant them shallowly so that the top of the rhizome is visible just above the surface of the soil. You can add a light sprinkle of bone meal to the hole before setting in the rhizome. Water well at the time of planting, but then only water once every 10 days to two weeks, until the winter rains return. If the winter brings tremendous freezing temperatures, you can pile some winter protection, such as evergreen boughs or straw, over the rhizomes. Remove winter protection when you see new foliage shoots emerge in the spring. Remember to fertilize in the spring about a month before bloom time.
August 15, 2012 at 8:24 pm
My iris is located in an area where the public can see them and they look awful right now with their leaves turning yellow but you say it is not good to cut them-any suggestions?
August 21, 2012 at 2:28 pm
We do recommend that the Iris foliage be left in tact until fall. You may, however, trim just the brown or yellow ends if you prefer. Ultimately, in the best interest of your Iris investment, you want to leave as much green foliage on the plant as possible. The foliage collects the nutrients from which the rhizomes build their mass for healthy growth the following spring. You may remove any papery brown leaves from the plants without any negative impact, however. All the best and happy gardening!
August 8, 2012 at 1:53 pm
Great blog! I want to hear about how and when to divide overgrown beds, what is good to plant with them so there is something in the bed when the iris fades, and drying roots for orris powder.
August 9, 2012 at 9:24 am
Thank you for the comment, Leanne. I’d love to learn more about orris powder myself, but sadly I do not claim any expertise in the art of botanical medicines. As for dividing and companion planting, however, I’ve got lots to share. Iris beds should, ideally, be divided and transplanted every 3 to 5 years. Beds that have become matted can still be dug up and carefully sectioned into individual rhizomes for transplanting. Be sure to amend the soil with compost, fertilizer, etc. before transplanting, as the soil has likely become depleted of essential nutrients. See our “How to Grow Iris” pages on our website at http://www.schreinersgardens.com for further details. I will post a brief article on companion planting soon. Happy gardening!