Thursday, December 22, 2011

What is Rebloom?

Iris shows have been among my favorite events for well over two decades. I’m the gabby type and love to talk to new people at the shows. Sharing is what it’s all about and I really like to infect others with the iris virus. When they hear I breed rebloomers, their first question is “What is that?” Then, they often say, “I’ve never heard of them!”

According to the American Iris Society Judge’s Handbook, “A reblooming iris (usually marked RE) is one that blooms in the spring and again in the same growing season.” They can appear in all iris classes. My twenty six years of work as a hybridizer has been focused on rebloom in the tall bearded class for zone 6. I reserve the right to chase distractions!

Rebloom is categorized according to the arrival of that additional bloom season. Currently, there are at least four different rebloom classes based on their rebloom behavior. This is important since all types will not rebloom in some climates.

Repeat bloomers usually put up additional stalks about six weeks after the spring season. My ‘Summer Radiance’ creates a lot of interest when it blooms in July. The bright shiny yellow blooms can be seen for a great distance.

Summer Radiance (Wilkerson 1996) 

Cycle rebloomers have a distinct second season of bloom in the fall. It usually follows a fall rain and cooler temperatures. In my zone 6, southern Kentucky, most cycle rebloomers open around October 1. A good example would be my own ‘Radiant Bliss.’ Louisville is more than a hundred miles north of my garden and they get fall rebloom earlier due to their earlier fall weather.

Radiant Bliss (Wilkerson 2005)

Sporadic rebloomers produce unpredictable bloom stalks at varying times. These are the ones I call warm climate rebloomers. They do well in the southern tier of states, the west coast, and Australia. They rarely show reblooming tendencies in colder climates. When they bloom off season here, I’m like a kid in a candy store! Just as thrilling are the reports of rebloom on some of my non-reblooming children once they move to California. Both ‘Gilded Cream’ (Wilkerson 1995) and ‘Color Me Mysterious’ (Wilkerson 2011) are from rebloom breeding and have rebloomed in California.

Gilded Cream (Wilkerson 1995)

Color Me Mysterious (Wilkerson 2011)

Endowed with stronger rebloom genes, multiple blooming irises have the genetic ability to bloom any time from spring through the first hard freeze. They were called ever blooming in the past, but this was misleading, as people expected them to bloom constantly from spring thru fall. Another term you may hear is whenever bloomers. They have this ability, but most will not automatically bloom this second time.

I’ve posted a couple of photos of multiple (summer) irises growing and blooming with dahlias as proof they do bloom here in July and August, although it’s not a guarantee. ‘Immortality’ (Zurbrigg 1982) is with the red dahlias and ‘Returning Chameleon’ (Wilkerson 1995) with pastel dahlias. ‘Immortality’ is the pollen parent of ‘Returning Chameleon.’

Immortality (Zurbrigg 1982)

Returning Chameleon (Wilkerson 1995) 

With all rebloomers, much is determined by cultural practices and climate. In my zone 6 garden, it’s important to fertilize after the spring bloom and also to keep the plants well watered. If they do not receive approximately one inch of water every ten days or so they will go dormant and this will stop the rebloom. I recommend soaker hoses so the foliage doesn’t get wet in the hot summers.

The spring only bloomers need to go dormant for the summer and may (often) rot under the very conditions that rebloomers require. Again, water and extra fertilizer create extended summer growth which can and does create rot in many spring only blooming irises. If you grow several rebloomers, it would be best to grow your rebloomers separate from the spring only irises.

On a personal level, I consider rebloomers to be garden irises. I make a conscious effort to promote good branching in my seedlings, just in case they make it to an AIS sanctioned show either spring or fall. It’s rare that rebloomers are seen at the National Convention Gardens, or in spring shows. “Why is this?” you ask. Timing! Most rebloomers have an early spring season and have finished blooming by the time the shows and the tours take place. In the off season, they are the stars of the garden.

For the record, I don’t go crazy over terminology. I will report rebloom in this way, “It’s blooming now, or it bloomed at this time.” There are no guarantees with rebloomers. Mine is a difficult climate. I get excited over maiden (first) bloom in an off season, even though I know it may never rebloom again. I’m depressed at the end of spring bloom season and I dislike the first freeze each fall. I’m such an iris addict that I welcome, encourage, and enjoy an iris blooming at any time. Sometimes I think the breeding program is just a way to stay involved in irises year round!

How did I get involved in reblooming irises? In 1982, the Henry Field’s catalog listed “fall irises!” This was my introduction to reblooming irises. Thus, my obsession began. If you love irises, why not grow the type that blooms a second and sometimes a third time per year? If I had my way, everyone would grow and breed rebloomers. Don’t you agree?

There are Internet sites, including the American Iris Society, where you can increases your knowledge of irises in general. Many things, including the iris encyclopedia and commercial links, are available through the AIS site.  There is a Reblooming Iris Society devoted to rebloomers specifically. There are archives in place for both iris talk and iris photos, online email lists about irises.  These archives contain a really good supply of iris information with a search engine. Good reading for the winter season.  

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