Jim McKenney
Tue, 09 Mar 2004 15:42:34 PST
Irises which do (or have done) well here in my Maryland garden include some
reticulatas (more below), some junos (ditto), Dutch iris (ditto), a wide
range of bearded iris, Iris pseudacorus, I. foetidissima, I. ensata
(glorious with our native lilies if you can get the timing right!), I.
tectorum, I. cristata, I. verna, I. prismatica, I. dichotoma and lots of
other odds and ends. 

I. tuberosa (Hermodactylus) is apparently only marginally hardy here: it
typically experiences significant winter foliage damage and declines. Mine
are scheduled to move into a cold frame.

Junos such as bucharica, magnifica, graeberiana, willmottiana alba and, I'm
happy to say, cycloglossa do well if kept dry when dormant. I no longer
grow magnifica, graeberiana and willmottiana. Magnifica was a big lusty
grower which went up to 18" high. Iris cycloglossa is only in its second
season here, so maybe I'm counting my chickens...Persica and its relatives
are apparently not for the open garden - they're too tricky. 

Dutch iris apparently have to be dug for reliable year to year bloom.
Otherwise they decline and disappear. 

Jane mentioned English iris. "Far better is the "English" 
(actually Spanish) Iris latifolia, which comes in a number of color 
selections and doesn't make growth until spring. It should be a standard 
border plant in Mediterranean climate gardens." Evidently these are
hopeless under our conditions. Is anyone out there growing these
successfully under mid-Atlantic east coast conditions? Last fall I had
ordered some Spanish iris (the term Spanish iris in commerce usually refers
to Iris xiphium derived hybrids for which there was a vogue in the past;
when the Dutch hybrids appeared, the Spanish iris more or less disappeared.
As Jane correctly points out, the "English" iris is actually Spanish or
Portugese in origin and probably was a by-product of the Port trade). Well,
back to the story: the bulbs I received as Spanish iris were huge, the size
of small hen's eggs. Obviously they were not Spanish iris; I expect them to
be "English" iris and I'll let everyone know when and if they bloom. They
are emerging now. The literature suggests that if I'm lucky they will bloom
for a season of two here before they quit. 

Commercial reticulate iris are apt to disappear without help here after a
few years. Some persist better than others. The red-purple ones such as
J.S. Dijt, Pauline (or is it Paulette?) and "old original" seem to persist
best - indefinitely if conditions are at all good. By "old original" I mean
the old commercial form of Iris reticulata, the one with a sweet violet
fragrance and red-purple (but with more emphasis on the purple) color. I
have plants in the garden which were originally planted in either 1961 or
1963. I think I've gotten my money's worth with these! 

I mentioned that some disappear without help. What is "help"? In this case,
dry summer conditions and feeding. Some I cannot keep: the hybrid Natasha,
a look-alike for Iris vartanii alba for those of you old enough to remember
that - seems especially likely to disappear (as does I. danfordiae) under
garden conditions. It's really idiotic of me to expect them to flourish
under garden conditions. The writing is on the wall, and I refuse to read
it: we have virtually no true bulbs in the local flora. Our soils eat
bulbs. People have been planting bulbs here in eastern North America for
centuries; by now they would be thick as grass (or thick as Ornithogalum
umbellatum to cite the exception which proves the rule) if they survived. 

If it's valuable, dig it and store it under cover. 

Here's where we are in the iris season: the first hybrid reticulate iris
are open and the cultivar Lady Beatrix Stanley (generally attributed to I.
histrioides) is about to open. I. danfordiae is in full bloom, but I don't
count those because I did not really grow them - they were newly planted
last fall. Otherwise, lots of buds poking up everywhere. 

Jim McKenney 
Montgomery County, Maryland zone 7 where, given the length of this message,
I might be giving Iris herself some competition for the job of messenger of
the gods - or at least messenger of the gardeners.    

At 09:31 AM 3/9/2004 -0800, you wrote:
>Regarding Iris species that grow well in my area, I would agree with Mary 
>Sue that the Pacific Coast species and their natural and garden hybrids are 
>the most dependable. They are useful for holding the soil on banks and for 
>providing a grasslike foliage contrast when out of flower. The flowering 
>period is short, in late spring to early summer.
>All Pacific Coast irises flower best in sun here, although they can often 
>be seen growing in woodland in the wild. They are adapted to persisting 
>vegetatively when shaded, and to flowering and increasing by seed when the 
>tree or shrub cover is removed by fire or other means. The seeds can remain 
>dormant for many years, germinating when the soil is disturbed -- which 
>suggests shallow sowing. This pattern is also observed in an iris endemic 
>to my area, I. tenuis, the only western North American member of the 
>crested iris group. It forms huge colonies in shade, but flowers much 
>more  in open situations such as road cuts and under power lines.
>If I can get healthy bulbs of Iris reticulata, Iris histroides, and their 
>hybrids, they are long-lived in the garden in areas not watered in summer. 
>They flower best if planted deeply. The problem is that most commercial 
>stock is infected with ink spot disease, which soon debilitates the plants 
>once they are not subject to the Dutch cycle of lifting, treatment, and 
>controlled storage. Growing I. reticulata from wild-collected seed was a 
>revelation for me: plants three times the size of commercial varieties, and 
>setting big seed pods.
>A few bearded irises have persisted here, notably I. albertii, wild forms 
>of I. pallida, and I. subbiflora. I gave up on bearded iris hybrids years 
>ago when I found that they do not tolerate competition from neighboring 
>plants and suffer incessantly from diseases and slug predation. One might 
>as well grow hybrid tea roses.
>Some Juno irises seem to be doing all right outdoors here, in particular I. 
>magnifica, I. vicaria, and I. bucharica, all of which are readily 
>available. I grow them on the rock garden. Now I'm trying some selections 
>of the Regelia species I. stolonifera outdoors. Oncocyclus irises cannot be 
>grown in the open in the Pacific Northwest, and hardly can be grown under 
>cover, unless you use fungicides and keep them dry until late winter.
>The bulbous irises of the Xiphium section are represented in our gardens 
>mostly by "Dutch" irises, which don't persist here over many years since 
>their winter-growing foliage gets frozen. Far better is the "English" 
>(actually Spanish) Iris latifolia, which comes in a number of color 
>selections and doesn't make growth until spring. It should be a standard 
>border plant in Mediterranean climate gardens.
>Iris unguicularis is increasingly grown in the Pacific Northwest, though it 
>can be expected to suffer in our colder winters. (I keep some in the bulb 
>frame as insurance.) Its close relative I. lazica is more cold-hardy and 
>flourishes here, as do most plants from the Pontic region, its home. It 
>grows well in part shade but flowers better in sun, though its evergreen 
>foliage can sunburn in the latter situation. It blooms in early spring and 
>unlike I. unguicularis has little fragrance.
>Spuria irises do very well here, but they are grown mainly by specialists, 
>since they take up a lot of space for the sake of a very short season of 
>proportionately small flowers. Siberian irises are fine as long as I get 
>them in spots where the soil is retentive enough. Iris cristata cannot be 
>grown here because of the slugs, which love it intensely. Japanese irises 
>(I. ensata) do not flower for me, I suspect because of too much night 
>cooling at this elevation; they are hot-and-humid-summer plants and do fine 
>on the valley floor 1500 feet (500 m) below me.
>Jane McGary
>Northwestern Oregon, USA
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