RE: iris lifespan - Iris setosa

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What you write is a good explanation of why Iris setosa is not found in the wilds of NY (if there are any wilds left in NY, that is.)   Iris setosa is a VERY widely distributed iris in the northern parts of the world.  I think it is almost circumpolar (north pole, that is.)

 

I. setosa is THE iris of our Alaskan wilds.  It is very long lived and seems to prefer soil moisture at least part of the summer.  A fair amount of organic matter is usually on the soil surface, including old iris leaves from previous years.  This also keeps the soil cool.  (We usually say that cold soils are our main limiting factor to growing some vegetables but I really do not know what that temperature range is around here, but I am guessing that raised beds will probably get up to 60*F.)

 

We seldom, if ever, get over 80*F in a summer so heat stress is not a problem here.  The heat you have (or maybe the resultant moisture stress) is probably the problem that your I. setosas have and your winter temperatures fluctuate too much.   

 

The soil here seldom thaws before spring time, so the plants do not get false starts and waste energy during warm winters you all often have.  We seldom get “late freezes” in spring/summer or “early freezes” in summer/fall. 

 

These wild iris are usually in open (treeless) areas and usually have damp soils at least part of the summer.  There was one area just north of town that was TOTALLY iris blue color when the flowers were out (and totally hot pink when the shooting stars were blooming) up until the early 1970s.  That area settled down some 2-5 feet or so in the 1964 earthquake and allowed brackish water to flood the area with very high tides. The irises are not as thick as they used to be because people have been digging the iris out by the pick-up truck loads for decades (even though it has been illegal all this time.)  It is so sad that this spectacular natural wonder was and is continuing to be plundered.

 

In my Anchorage garden (which is a bit warmer than the nearby wild) the I. setosa is starting to grow by mid-May and leaves start to turn yellow mid-August to mid-September (with plants in the dry soil areas turning yellow first and plants in moist conditions still having green leaves until freezing.)  In moist soil conditions the leaves are much larger and the clumps much more vigorous, while dry conditions produce plants that barely multiply or flower – but they are still able to live 20+ years in these “bad” conditions.

 

Clumps two feet across are common.  In large clumps, the center is sometimes empty – which is like most other perennials.  A seedling can easily make a clump about a foot across in five years if happy with normal moist garden soil.  If I forget to collect the seeds, there will be so many seedlings in the garden you would swear that it was a patch of lawn had somehow moved into the garden!

 

Around here, even in the most abandoned of gardens, if you find any plant still alive it will be Iris setosa and other native plants growing in the grass. 

 

I hope this sheds some light on the Iris setosa portion of your conversation.

 

Debbie Hinchey

Anchorage Alaska – USDA Zone 3/4.