Tuesday, November 29, 2022

Growing Irises Out East: Sharing Stories of Rebloom

by Heather Haley

In addition to being a member of the American Iris Society (AIS), I am an active participant and volunteer in North Carolina Cooperative Extension programs. I completed the NC Farm School program 2019. Earlier this month, my husband Chris and I hosted a farm visit for another Farm School graduate, her instructor, and a new horticulture extension agent in our county. 

Heather's family with reblooming iris 'Mesmerizer' on their farm in Ramseur, North Carolina
photo by Grace Kanoy, GeoCore Creative Inc.

Winter is approaching quickly, and Chris and I spent that morning straightening up the kitchen -- just in case we needed to move farm conversations inside. When the visitors arrived, they were met with spring-like conditions and all enthusiastically wanted to visit the production field for bearded irises. The intent of this visit was to support a beginning nursery owner, discuss interests, and share experiences in the business of horticulture. However, once visitors realized the farm had several irises blooming in mid-November, they lost all thought of business pursuits and became highly inquisitive about these plants. 

One inquired, "Are the irises CONFUSED?" I laughed gently and replied, "No. Those are rebloomers. They are just doing what they do best."

Chris and I explained that each of the various irises on our property has genetic information coded in their DNA. Differences in DNA make each iris interesting and different from other varieties. Some iris genes control traits like flower color, whereas others can modify growth and reproductive cycles. With the right DNA sequence, an iris can shorten or skip summer dormancy and proceed directly into its next growth cycle. If climate and cultural conditions are just right, it is possible for daughter rhizomes to bloom in the same year as their mother. These irises aren't confused; they are just unusually prolific. Science buffs use the term "remontant" to describe plants that flower more than once in a growing season. "Rebloom" is the colloquial term for this phenomenon, and an entire chapter on it appears in the third AIS study of the genus Iris: a 1978 book titled The World Of Irises*. 

*The World of Irises book is now out of print, but used copies can be found online. Wayne Messer and Bob Pries have also transcribed select book chapters (including Raymond Smith's chapter on Rebloom) for Iris Encyclopedia. AIS is always looking for volunteers who can type existing content into this online library. If you are interested and available for transcription projects like this, please reach out to Bob at bobpries3@gmail.com. 

Chris reminisced about our household's earliest experience with a reblooming iris. After spending years in apartments during our college years, Chris and I became first-time homeowners and took to gardening in earnest. A modest collection of 19 irises arrived in September 2012 and were gifts from my mother Alleah. We planted them on the north side of the house where they would have good drainage and receive plenty of sun. Among these irises was 'Peggy Sue.' Alleah's description of this iris was deceptively plain: Peggy Sue - L. Lauer '06 - pink, red beard, lightly ruffled.  Although we didn't know it then, 'Peggy Sue' was destined to confuse and delight us. 

Several of our new irises bloomed the following spring, but 'Peggy Sue' wasn't among them. Her first bloomstalk appeared much later . . . in NOVEMBER! We were ecstatic to enjoy a flower in bloom, but also wrongly assumed this iris was confused. I posted a garden photo on Facebook, and included it in an e-mail to other members of the family.

Fall 2013

I suspected this bloom might be evidence of global warming, but my mother set me straight. Alleah was, and still is, vastly more knowledgeable about irises she chooses to maintain in a garden setting. Her response was, "I hate to burst your bubble, but 'Peggy Sue' absolutely knows it's November and is doing the right thing. She blooms EML and RE (AIS abbreviation for early, midseason, late season, and rebloom). . . . So whether or not I labeled the iris RE, she is. I'm attaching the October Santa Rosa Iris Society Newsletter in which I printed a long article on successful rebloomers in California and referred to a commercial garden in Virginia that specializes in rebloomers." 

Alleah's email continued with gems of motherly, irisey, and scholarly advice. "You may wish to go online and see a list of rebloomers in that geographic area and ask for some . . . .  Reblooming is a recessive trait. An iris breeder improves his chances of getting a rebloomer by crossing two rebloomers together, or involving several rebloomers in his line. 'Peggy Sue' has 'Pink Attraction' (RE) in its background, although none of the other irises in its background were registered as rebloomers. You will have to find other evidence of global warming."

Spring 2014

After planting some extra rhizomes of 'Peggy Sue' in the backyard, it became obvious that 'Peggy Sue' in the front yard had better growing conditions. These conditions led to more consistent bloom and rebloom in the front yard compared to the back. Rebloomers appreciate being watered throughout the summer. Frequent rain combined with a leaky hose spigot provided front yard 'Peggy Sue' regular access to water when she wanted it. She responded by blooming regularly and making lots of increases.

Fall 2014

Early Spring 2015

Very Early Spring 2016

Being located close to the foundation of our house also allowed for slightly elevated temperature. Bricks can absorb and store thermal energy from sunshine during the day. When the sun went down, the bricks slowly dissipate stored energy to their surroundings, including front yard 'Peggy Sue.' As years passed, we got several earlier- or later-than-usual bloomstalks, resulting in bloom for Thanksgiving and Christmas! Each time she bloomed, my inner Buddy Holly started singing, "I love you Peggy Sue, with a love so rare and true. Oh, Peggy, My Peggy Sue!"

Late Fall 2015

Winter 2015

Late Winter 2017

'Peggy Sue' was not the only iris we that rebloomed for Chris and me in Mebane, but it was one of the more memorable cultivars we maintained there. Of 80,000+ irises registered with the American Iris Society, about 4,246 (0.5%) are known to exhibit rebloom. By 2015, I was eager to get more rhizomes of reblooming irises. Unfortunately, many of the rebloomers I added didn't seem to like us very much. They didn't die, but only three of the twelve irises Alleah gifted to us demonstrated rebloom. I tried following conventional advice by providing more water and fertilizer, but most never bloomed more than once in a growing season. Thankfully we had better success with the rebloomers I purchased from Alleah's grower recommendation in Virginia, and from rhizome sales hosted by my local iris society. 

'Daughter of Stars', Late Summer 2018

'Bonus Mama', Early Fall 2018

Eventually, I learned that irises that rebloom in one climate (e.g., my mother's garden in California), may not be well suited for rebloom in another (e.g., my garden in North Carolina). I started paying close attention to Colin Campbell's work gathering rebloom data in my region, and combing through back issues of the Reblooming Iris Recorder for reports from gardens closer to me. I joined the Reblooming Iris Society (RIS) in 2021, and could access newer issues of the Reblooming Iris Recorder as they became available. While attending the National AIS Convention in Las Cruces, New Mexico, Alleah and I each purchased the 2022 edition of the Cumulative Checklist of Reblooming Irises

This must-have resource is available as a printed book, flash drive, and digital file sent by e-mail 

Alleah likes using paper reference materials and purchased the rebloom checklist as a spiral-bound book. I prefer having electronic reference materials and purchased a flash drive that contains a .pdf copy of the checklist, as well as a spreadsheet version of data used to create the checklist. I store the rebloom spreadsheet on my phone so I can access needed iris information quickly. The 2022 edition of the rebloom checklist builds on prior editions from 1975 and 1988, which contained 641 and 1,428 varieties respectively. To create these must-have iris resources, the Reblooming Iris Society engages in what I would call "citizen science." Iris enthusiasts, including hybridizers and iris lovers from around the world, voluntarily track the bloom and rebloom behavior for the named iris varieties each growing season. Next, volunteers share their rebloom data with an RIS Area Director who pools rebloom data and organizes it for publication in the Reblooming Iris Recorder, and subsequently in a checklist.

For years, I aspired to track and report my own rebloom data. However, I always struggled to find time and energy to do it. That is . . . until I remembered that I photograph most irises and their identification tags with my cell phone when they bloom. My cell phone records the date and location of my pictures automatically. EUREKA!

Earlier this year Mary Platner, editor of the Reblooming Iris Recorder, called and asked if I would be willing to track rebloom for irises growing at the farm in Ramseur. I was hesitant and explained that most of our irises are recently planted and receive no supplemental water. Mary lives in Scottsdale, Arizona and has her share of irrigation issues. She assured me that my rebloom data would still be valuable and I agreed to help. Bloom charts can be filled out on the computer or printed on paper. Mary provided me with an example chart, and her instructions were easy to follow. Each month is divided into three columns. If the day of the month an iris blooms is between 1 and 10, an "X" is placed in the E column of the appropriate month. Similarly, if it blooms between days 11 and 20, the M column is marked. Finally, if it blooms between days 21 and 31, the L column is marked.

Bloom Chart Directions 2022

Now that overnight temperatures on the farm are below freezing, our 2022 bloom season has ended. I'll use data stored in my phone to chart if and when my reblooming irises came into flower this year. When all is recorded correctly, I plan to email completed bloom charts to my assigned RIS Director and give Mary a heads-up that they are finished.

Hopefully, sharing our experiences will inspire you to add rebloomers to your garden and take part in data collection efforts. Working together, we can help everyone understand reblooming irises better, and rest easy knowing these genetically interesting plants are certainly NOT confused.

1 comment:

  1. Interesting post. I have several iris in huge pots and one is now spending nights in the shop hoping to avoid a freeze as one last bloom continues to flourish. She's opening up a bit today, so maybe all the coddling has been worth it. There's also a couple of seed pods that I'm hoping will ripen. I'd like to see what they produce. Just for the fun of it. Anyway, thank you for the article. I'll be saving it to come back again and as a connect to your other post. Phyllis