Spanish iris

Jim McKenney
Sun, 23 Jul 2006 09:19:04 PDT
Eugene Zielenski, in commenting on the culture of English irises, asked " Is
Pennsylvania a mid-Atlantic state?  "

In response, I would say depending on the context, maybe. 

It seems that English irises have been grown successfully in New York State
and northward (I'm basing that partially on the account in Molly Price's The
Iris Book). 

So to go back to Eugene's question, I would say that western Pennsylvania is
not for purposes of this discussion a middle Atlantic state. I had in mind
the piedmont and coastal plain areas, the areas of the major, old cities in
this area. For horticultural purposes, the conditions in the physiographic
provinces west of the piedmont are significantly different. The zones of
similar conditions in this part of the country run roughly southwest to
northeast. As you move westward, especially as you cross physiographic
provinces, conditions change rapidly. 

So my question for Eugene is "Where in Pennsylvania were you growing those
English irises?"

And I'll bet it was not on the coastal plain or piedmont. If it was, please
tell us more. 

There is a sort of gray eminence in this discussion of the culture of
bulbous irises, a gray eminence to which I have not called attention. But I
have mentioned it in other posts in the past. What I'm referring to are the
bulletins written by David Griffiths and published back during the 1920s and
1930s by the USDA. These discuss bulb culture in hugely interesting detail.
One such bulletin is devoted to the culture of bulbous irises of the
Spanish, Dutch and English groups. 

Griffiths reported levels of success compatible with commercial production
for Spanish and Dutch irises in diverse parts of the country (North
Carolina, Virginia, Tennessee, Illinois, Michigan, New York, California, the
Pacific Northwest). 

He reported widespread failure with English irises outside of the Pacific
Northwest (the Puget Sound area is evidently ideal for them) and some colder
northeastern states (New York and Massachusetts). 

Of particular interest to me is that one of the sites for his work was a
place called the Arlington Experiment Farm in Rosslyn, Virginia. Rosslyn is
now a heap of high-rise buildings clustered at the edge of the Potomac River
opposite Georgetown, Washington, D.C. I pay particular attention to any
comments Griffiths made about successes and failures at Rosslyn - these can
fairly be expected to predict success or failure for me because Rosslyn is
only about twelve miles from here as the crow flies.  

English irises were a failure for Griffiths in Washington, D.C. 

So, Eugene, where in Pennsylvania were you growing those irises? 

Jim McKenney
Montgomery County, Maryland, USA, USDA zone 7, where I'm awaiting the
delivery of a peck of freshly picked peaches; when the peaches get here, you
won't be hearing from me for awhile. I'll be preparing and eating peach pie
and peach ice cream for the next few days.

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