Monday, March 18, 2013

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.

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