Exploring the Mysteries of Bloom Season & Height: The Historics

By Mike Unser

One of the first things anyone beginning to research historic bearded irises is confronted with is the often contradictory designations about the classification of varieties by size and/or bloom season. It is difficult enough to get an idea of these terms in just the bearded iris realm, but it is even more confusing when you realize that other species may conform to their own definitions. For the next several weeks we'll be exploring the different aspects of these topics here on World Of Irises, and I'd like to start by clearing up a little confusion for those new to historic bearded irises.

When the American Iris Society was first formed in 1920 one of the first major projects they instigated was a census of all the literature regarding irises, which was used to create a Checklist of all known cultivars to that date. This was a years long undertaking of Ethel Anson S. Peckham first published in 1929 and remains the premiere work of its type in irises. This, along with registering new cultivars, was an attempt to bring order to a chaotic situation, to sort out authentically named varieties from impostors, as well as to bring worthy varieties with correct names to prominence and to document their parentage in order to bring organized principles to the improvement of the genus. In 1939 a revised and updated Checklist was published that built on the earlier work and expanded it enormously. It is an invaluable tool for anyone interested in the history of garden irises, and we owe Mrs. Peckham a great deal of gratitude.

One of the first things one will notice when comparing current glossaries with the original checklist is that the designations for bearded irises fall into just three classes: dwarf (DB), intermediate (IB) and tall (TB). This continues into the 1949 Checklist. With the 1959 Checklist we finally see the classifications we are currently used to: the dwarfs have been split into Miniature Dwarf Bearded (MDB) and Standard Dwarf Bearded (SDB), IB is still there with some alteration, Miniature Tall Bearded (MTB) and Border Bearded (BB) are new, and with TB still at the end but not with the same in definition as before. Bob Pries wrote in a recent article in Flags:

TBs were defined in 1939 as irises over 17 inches tall and Dwarfs were up to and including seventeen inches. Of course the Dwarfs had not yet been split into miniature dwarfs and standard dwarfs. The median classes, of MTB, BB, and IB did not quite exist between 17 and 27½ inches. I say not quite because the talls of the time were also sorted by bloom time with the class of IB. But IB, or intermediate bearded referred to bloom time and did not have a sharp cut-off of 27½ inches.

And that is where the confusion mainly comes in - Intermediate Bearded originally referred to season of bloom, not height or size. The first crosses between dwarfs and talls resulted in varieties of all heights that mainly bloomed after the dwarfs and before the talls, and that is what was used to distinguish the different classes. In the 1950's the AIS instigated a further division and reclassification into the current model, using not only bloom time but height, bloom size and other attributes to determine how a variety was to be classed. Now, IBs need to not only bloom between the dwarfs and the talls, but have an ideal range for height, bloom size and other attributes as well. The dwarfs and talls have similarly been broken down into more specific classifications. In the early 1960's older varieties were reclassed in a new Median Iris Checklist to bring them into as close of conformity as could be determined to the new model.

All of these changing definitions can be very confusing for someone new to the history of irises to sort out, but once this basic timeline and 'definition drift' has been taken into account we can better make use of the published materials that are so important to the historic iris enthusiast.

The following are a few examples of some historic irises that have been reclassified from their original designations into our modern system of designation.

One of the most widely grown irises that has been reclassified is 'Sans Souci' (Van Houtte, 1854), one of the many sports of 'Honorabile', a variety with proven hardiness and a penchant for throwing out sports of its own. 'Sans Souci' had been classed as a Tall Bearded variety originally, but is now listed as a Miniature Tall Bearded. Oddly, 'Honorabile', to which it is identical in all respects but color expression and tone, was originally classed as an IB. All the sports in this family are now classed as MTBs.

'Titmouse' (Williamson, 1934), was originally classed as an Intermediate Bearded iris, but has also been moved to the ranks of the MTBs.

Grace Sturtevant's lovely little 'Tid-Bit' (1925) is an example of a variety formerly listed as a dwarf Bearded that has moved on up to MTB as well.

Three irises originally in different classes, now sharing the same designation. Is it any wonder folks get confused when researching historic irises? The new designations are not always a perfect fit, but they are the best we can do with varieties that were never created to conform to our current standards. In upcoming posts our other authors will explore how bloom season and height designations are treated in the median and tall bearded classes currently, as well as how these are classed in other iris species. Stay tuned!

Exploring the Mysteries of Bloom Season & Height: The Louisianas

By Ron Killingsworth


Recent posts have discussed the history of classifying irises by bloom time and the related issue of height, along with the change in naming the different types of irises (here).   Now we shall discuss Louisiana (LA) irises.  Their full season is about a month and a half to two months.  The season begins during the end of the Tall Bearded iris bloom season and continues for two to three weeks afterward, so they are a great season extender if you love irises. In Louisiana, the New Orleans area starts the show with bloom beginning the first of April. In the NW part of Louisiana they bloom from mid-April to mid-May. In upper state New York they bloom in late June.


LA iris bloom time designations include early, mid and late season.  Early bloomers normally bloom the first two to three weeks of the season, followed by mid season blooms from three to six weeks and then finally the late bloomers from six weeks to finish. There are some LA irises that are registered as blooming somewhere between these designations- such as mid-late and early-mid-season.  Some are registered as VL for very late in the season.  The time of the season in which the particular cultivar blooms is determined by the person registering the iris, and that depends on where they live and when bloom time begins in that area.  So there is no hard-and-fast rule about when LA irises will bloom in your neck of the woods.


'Clyde Redmond' is a dependable early bloomer.

'Clyde Redmond' (Charles Arny - 1970)   Mary Swords DeBallion Award 1974

'Miss Gertie's Bonnet' is a mid-season bloomer.

'Miss Gertie's Bonnet' (Dormon Haymon -1999)  

The popular and widely distributed iris  'Black Gamecock' blooms very late in the season.

'Black Gamecock' (Frank Chowning 1978)  

Of the 2400 or so registered LA irises, 526 are registered as early season, 309 are registered as early-mid season, 1423 are registered as mid season, 415 are registered as mid to late season, and 104 are registered as late season.

The only problem bloom season causes for me is when I want to hybridize a late blooming LA iris with an early blooming LA iris. I can save pollen from the early bloomer and cross it to the late bloomer but it is almost impossible to save pollen from the late bloomer to use on an early bloomer the following year.  Most late blooming LA irises have the species iris brevicaulis in their genealogy and many of these late bloomers display a characteristic of iris brevicaulis - a tendency to bloom down in the foliage. 'Black Gamecock' is a late bloomer and it often has blooms deep within the foliage, which also tends to fall over when the bloom stem is heavily loaded with blooms - another characteristic of iris brevicaulis.



How are LA irises measured and how tall are they?   They have a wide range of heights, measured from the rhizome to the top of the bloom stem.  'Black Gamecock' is registered as 24".  'Little Rock Skies' (F. Chowning 1978) is another late bloomer and is registered as 28".

'Little Rock Skies' (Frank Chowning 1978)  Late bloomer registered as 28"

Among the most useful and garden-worthy characteristics of LA irises is their diversity of size.  Unlike bearded irises, which are divided into many size divisions, all LA irises are entered into the same division in iris shows.  That is why they are always placed on a very low table or directly on the floor of the show room.  Judges are then faced with some varieties that are as small as 24" as well as some varieties that are as tall as the judges!

In a quick search, I found 81 LA irises registered at 24-30".  I found two registered at 60".  But I have seen LA irises taller than me at 76"!  These are usually the species iris giganticaerulea.  

Benny Trahan and Pat Norvell with Iris Giganticaerula found in the marshes of south LA

Most modern hybrids of LA irises range from 30 to 50". The beauty of such a wide height range is you can plant irises of smaller size in front of irises that tend to be taller.  By also choosing the irises by bloom season, you can have early tall bloomers in the back of your iris beds and late blooming shorter irises in the front of your beds.

Remember that the bloom season listed on the registration is determined by the person registering the iris based on experience in his or her part of the country.  The iris may not bloom at exactly the same time in your part of the country, so you may want to take that into account when you are planning out your garden.  And don't forget that LA irises do not need to be planted in ponds, they do well in most garden conditions as long as they have adequate water.

You can learn more about LA irises at Society for Louisiana Irises.

Exploring the Mysteries of Bloom Season & Height: Siberians

By Bob Hollingworth

It's really quite strange that we have never standardized how we communicate the bloom time or height for irises, even though these are required characteristics in registering an iris with AIS.  

The situation of bloom time as it refers to Siberians is exactly like the bearded irises as described by Jim Hedgecock in his recent post. To me the registration should indicate when this cultivar blooms in relation to other cultivars in the class, hence the E, M or L designations, maybe with a V(ery) added to indicate unusual earliness or lateness.  However, clearly some hybridizers use these terms not to indicate peak bloom time but duration of bloom with the designation EML, meaning, I suppose, that it starts early and blooms throughout the season and not that it can start bloom at any time in the season (which is quite unlikely, since relative bloom time is quite reliable with Siberians).

'Who's On First' (Hollingworth, 2008)

'China Spring' (Bauer-Coble, 1999)

The introduction of  I. typhifolia to US hybridizers about 20 years ago moved up the bloom season for Siberians since these typically bloom 2-3 weeks before the more familiar sanguinea/sibirica hybrids (although a few sibiricas can bloom quite early too). So the meaning of Early has changed a bit with time.  Cultivars with some I. typhifolia genes will likely bloom well before the pack, such as 'China Spring' and 'Who's On First,' or Dave Niswonger’s “China” series.  

The season used to end for us when derivatives of Bill McGarvey's later whites including heritage from 'Esther C. D. M.' and 'Gull’s Wing' opened up, such as 'Hooked Again'  or 'Blushing Violet' . But I believe we may have a new winner for latest to bloom - 'Pool Party'. The last two years this has bloomed for us so late you wondered if it would ever open - after many early cultivars were already bloomed out. However, this may not be typical since 'Pool Party' is registered as an ML bloomer not VL. We don’t grow 'Worth the Wait' (Schafer-Sacks, 2002) or 'Last Act' (McEwen, 1985), but the names suggest that they should be very late bloomers too.

'Hooked Again' (Jim Copeland, 2006)

'Blushing Violet' (Hollingworth, 2005)

'Pool Party' (Cole, 2008)

Unfortunately, it seems that nothing is ever that simple and there are a significant number of Siberians that repeat bloom (mostly rather sparsely) a few weeks after first bloom. If the repeat bloom period is clearly separated by a flowerless period, it is easy to characterize, but a few irises stagger along between these two seasons and never seem to be entirely out of bloom for several weeks. This characteristic probably this led to the most convoluted registration I know ('White Prelude', McEwen, 1993) which is registered as VE-EML-VL & RE!

Whether to indicate the “repeat” bloom in the registration (and advertising) is a matter of judgment for the hybridizer – but if this happens most years and gives a display that attracts attention, it certainly is justified. There is a genetic basis for this tendency.   Nevertheless, the nature and environmental conditions that govern "continuous bloom" and "repeat bloom" are still quite mysterious. It also seems that some Siberians repeat bloom more readily in some regions than others, which makes their characterization even more difficult.

Height is in some ways a bigger problem, since here we are giving absolute values (e.g. 25 inches) rather than relative ones (dwarf, median etc.) and of course this is going to vary from year to year and from place to place as growing conditions vary.  

With Siberians a good clump will often have blooms at several heights - shorter around the outside and taller in the middle.  This gives a desirable bouquet effect as seen in the photos above.  So which height to choose? And then again, the flower stems elongate during the bloom period and may end up several inches taller on the last blooms compared to the first ones.

I expect different hybridizers use different methods to handle this variability. I generally record the height of taller stalks (ground to top of flower) for several years before introduction and use the tallest year as the registration height. Why not the average? Because this way seems to me to best represent the genetic potential (under ideal  growing conditions) of the variety. What does everyone else do?

'My Little Sunshine' (Schafer-Sacks, 2010) 

In fact, since there are no size classes for Siberians as there are with bearded irises, exact height is not critical and it would be just as good to have relative classes for height as we do for bloom time.  Dwarf, median, and tall are convenient, but that’s not how the current system works, in part because “dwarf” has a specific meaning in the bearded world that does not translate to Siberians. We do have irises that regularly bloom much shorter than most others  ranging from the old sibirica nana alba (which is actually a sanguinea in all probability!) to more recent ones like 'My Little Sunshine' that bloom at around 12-15 inches.  Compare this to the giants of the Siberian world at 48 inches or taller!  Let’s leave  with the thought that the long and the short of the Siberian iris world might make a good topic for a future post.