Iris cristata and small woodland Iris

[McDonough]

The following posts from spring 2010 will help kickstart this topic as we head towards spring 2011.


Two photos of Iris cristata 'Sam's Mini', a low growing and floriferous variety found by Sam Norris of Kentucky.




The next photos show the early spring rhizomes when first emerging.  The rhizomes run on top of the soil, in fact, they prefer to slowly romp through the top layer of woodland duff or well decomposed bark mulch.  In this particular cultivar, the rhizomes amusingly look like they're leaping up and over like spawning salmon as they progress upstream.




Having never harvested seed on Iris cristata, I wanted to experiment with seed-grown plants to see what sort of variability could be expected.  I also needed to learn how to harvest the seed; when is the seed ready?  Every few days I picked a pod and snapped it in half to test the progress of developing seed inside.  Eventually a few pods started to show a small degree of whitening in color, and a few other pods actually dropped off (although remained unopened), surely ready to pick.  The succulent green pods of Iris cristata and some Chinese woodland irises are attractive to some sort of insect that gets to the pods before fully ripe; dastardly chipmunks & squirrels munch them too, so harvesting early when the seed is ripe enough makes sense.

In the photo on the left showing the seed pods, on the right notice the lobster-claw like leaf bracts that each hold twin seed pods, the long styles are persistent.  Initially when testing seed for readiness, the seeds were nearly clear or translucent... so I waited until they were a semi-translucent to nearly opaque tan or yellow color.  Harvesting the seed is as easy as snapping the pods in half, then gently squeezing the seed out.  They were sown fairly thick in flats, covered with fine decomposed pine bark mulch, covered with wire mesh to prevent digging by chipmunks and squirrels, and they'll spend the year outside, hopefully to germinate spring 2011.

[McDonough]

Two photos showing the mats of surface rhizomes on Iris cristata 'Edgar Anderson' in early April 2010, a relatively giant form of I. cristata, with the new growth more erect than most Iris cristata forms.  One can tell from the start, the cultivar 'Edgar Anderson' is going to be larger than most cristata forms based on the vigorous tall shoots.  




Iris cristata 'Edgar Anderson' flowered the same time as yellow Iris koreana, making me wonder about possible hybrids.  Got a large batch of seed, all was sown.  Most other Iris cristata varieties bloomed later when we had very hot days to 94-95 F (35 C), and as a result the flowers went by in just a couple days, and almost no seed set on those.  Got one seed pod on I. cristata alba, which I sowed next to the mother plant.




For several years my Iris koreana barely flowered and shrank in size, so I moved it a couple years ago to a new location.  I believe it was too dry where it was; the new location gets more light and has better humus-rich moisture retentive soil, and it jumped in size, flowered well, and now set lots of seed.




Interestingly, in 2010 Garden Vision Epimediums offered pre-sales on I. koreana "Select", reported as a "very floriferous clone" and "one that propagates well", promising that a cultivar name will be registered before the fall shipment.

[McDonough]

I've never had good luck harvesting seed on Chinese Iris species.  It helps being retired (wish I was) or unemployed (wish I wasn't, sort of), because I get to observe in much more timely detail about what plants are up to.  Year after year, I see big, fat, 3-sided pods on species like Iris koreana and I. odaesanensis, two wonderful Chinese woodland Iris species, but rarely ever get any seed, although do find seedlings of I. odaesanensis here and there.

I discovered that the seed pods are much like other ephemeral seeders such as Jeffersonia, Epimedium, and Corydalis, they are actually ripe and mature when they're still green, when they're "al dente" and not "fully cooked", but even more so with Iris koreana.  Harvesting the large seed pods while green (noticing that a few had gone over to yellow, but with nothing inside), and snapping the green pods in half, there's good seed in there, like golden kernels of corn with starchy appendages (elaiosomes) that are attractive to ants.



Iris koreana does a pretty good emulation of I. cristata, only with yellow flowers.  Darrell Probst tells me that he has tried crossing the two species, but thus far no hybrids.  One reason I'm interested in growing on the seed, maybe the bees will have better luck.

I also collected seed on I. odaesanensis and I. henryi much earlier that I would normally, and found a good percentage of viable looking seed.  Time will tell whether my early seed sowing efforts are the proper recipe for success.  Iris koreana was blooming at the same time, and within close proximity of I. cristata 'Edgar Anderson', so I'm interested in finding out whether the bees were up to any productive hanky-panky.

[McDonough]

Iris minutoaurea took several years to "settle down" before it started to flower well. In 2010 there was a fairly good flowering (2 photos), but the plant is being encroached upon and shaded by Epimedium x setosum; eventually I moved the Epimedium to afford more room for the Iris. No seed again this year, it got very hot when the plants bloomed and they went over too quickly.  I always forget to use some sort of scale object when photographing this plant, as it is so tiny in flower that it is hard to capture a true sense of scale.  




Both I. koreana (left) and I. minutoaurea (right) have the undesirable habit of expanding their foliage significantly after flowering, making larger (and untidy) foliage clumps than one anticipates, as compared to I. cristata that maintains the spring foliage size.

[McDonough]

I have never grown Iris cristata in pots, but have heard they are not the most amenable creatures for pot culture. Here in New England, northeastern USA, they are among the easiest and most satisfying Iris to grow, rapidly spreading and flowering prolifically.  The mistake people sometimes make with them, is to plant the rhizomes too deep. As you can see in the rhizome views I have shown, they like to run right on the surface, so are best planted in a layer of woodland duff or decomposed bark mulch.

Typically they make lots of seed, but I've never bothered collect seed until spring 2010.  My large mat of I. cristata 'Shenandoah Sky' growing under a Stewartia pseudocamelia tree, flowered prolifically as always (photo from 2008), but with several days of unusual heat (94 F - 35C) the flowers went over quickly and made no seed at all, I suspect because the process of fertilization did not have enough time as the flowers were toasted.




Same thing with two newbies in the garden, I. cristata 'Mountain Girl' (left) and I. cristata alba (right).  Both were planted in 2009, as 2-fan starts, and I'm pleased with how much they grew in just one year, and flowered spring 2010, but the flowers were no match for the heat. I was lucky to get one pod on alba even with the heat.  The one named 'Mountain Girl' is a 2007 introduction by Joe Pye Weed's Garden (Marty Schafer & Jan Sacks, breeders of amazing Iris), lovely light blue flowers lacking any yellow among the white signal patches.

[McDonough]

I have I. henryi and I. odaesanensis growing on a dry embankment, I. henryi seems to love the location, with about 200 blooms in 2010 (but only 4 plump seed pods) and for some reason the same year, I. odaesanensis barely bloomed at all, I think just 3 flowers, although the plant has spread to about a meter across and looks healthy otherwise.  I might split it and try growing some pieces in a more moist location.  Iris henryi and I. odaesanensis seem to grow as "turf" species, the old foliage persistent (evergreen, but still persistent in I. henryi), and in spring grow out of the mass of older foliage.  

left photo: March 2010, enbankment with I. henryi on the left, the evergreen foliage trailing down nearly 2' (60 cm), with the dead persistent foliage of I. odaesanensis on the right (don't even think about foliage cleanup, not worth the tedious effort).

right photo: late April 2010, the plants coming to life, I. henryi budded (lots of buds), and new foliage of Iris odaesanensis in the background, taking over the persistent old foliage.





Iris henryi, lots and lots of bloom, about 200 flowers.  This is a bi-flowered species, and a couple days after the first flush, it repeats itself with a second flush of the same number of flowers.  The flower color is the palest smokey blue, hard to capture in photos, but exquisite in every detail.






Iris henryi, setting lots of pods, but a false promise, as only 4 out of hundreds of pods would end swelling into a round lime-like ball to produce seed; in this photo one swelling pod can be seen.




Foliage of I. henryi and I. odaesanensis taken mid June 2010, really good on a slope where the foliage hangs down to follow the slope.




A photo from October 2008, showing the embankment after we've had some frost, the very narrow grass-like leaves of I. henryi on the left looking very much like the leaves on Carex caryophyllea on the right, with the turfy mass of I. odaesanensis taking on some yellow frost-induced color in the center.

[McDonough]

China has many lovely woodland Iris. At a 2010 garden tour at Joe Pye Weed's Garden, the amazing garden and nursery of Marty Schafer and Jan Sacks here in Massachusetts, USA, there was a planting with numerous Darrell Probst Iris collections from China.  I show just one such collection in bloom that day, a gorgeous little woodland Iris, among many listed as "Iris species novum" along with a collection number.  I hope some of these lovelies make it into horticultural commerce soon, and knowing of Jan & Marty's cultivation skills, and of Darrell's, maybe we won't have to wait too long.




There were many such clumps of various Iris species novum there; one had black stems and striking black bud spathes, the outer side of the ready-to-pop buds were light yellow, although Darrell assures me it opens to a light blue flower.  My photos came out lousy, so I only show one photo of another Iris species novum.




Also shown is Iris gracilipes 'Cobblewood Charm', a 2008 Joe Pye Weed's garden introduction, a cross between the I. gracilipes "Buko Form" (tiny miniature white form, found on Buko San [mountain] in Japan) and the regular taller blue-violet form.  In flower it is about 6-8" (15-20 cm) tall.

[McDonough]

In June 2010 I divided a clump of Iris cristata alba, and thought it might be a good opportunity for photo documentation.

In the upper center is I. cristata alba.  The previous year it was a two-fan plant, purchased from Garden Vision Epimedium in May 2009, for $6 US.  Certainly has filled out nicely in just one year.  To the left of it is a similar size clump of I. cristata 'Mountain Girl', and to the right the tiny plants are seedlings.  These plants grow at the base of Stewartia pseudocamellia, a tree with incredibly dense matting surface roots that make underplanting impossible for most plants, but Iris cristata can easily skim the surface bark mulch layer. In this photo, I used a sharp spade and trowel to mix the existing mulch layer into the loosened earth, the surface tree roots chopped out just to give the Iris divisions one season of competition-free growing.




Iris cristata alba clump uprooted. Don't be fooled by the seemingly dense root ball, most of those roots are Stewartia tree roots!




Typical division; usually the fans are paired, sometimes there is a third side fan.  In the center of paired fans is the spent bloom stalk and bracts.  Most roots are from the older joined portion of rhizome, but you can also see a couple new white roots emerging from the two fans, ready to dig in and anchor those fans, later this season to sprout forth with fresh new paired fans advancing the colony.




Left:  close-up of the paired fans and just-emerging anchor roots.
Right: paired fans spaced and ready to plant, with 14 divisions, a 14:1 increase in 1 year.




Divisions planted and watered in. It's hard to tell, but the rhizomes are left on the surface or just barely covered, but I do carefully place soil/mulch over the new anchor roots.  These divisions will get special attention and watering for the next month.




In the center, a 2-year seedling with 5 closely spaced fans that are attached to a developing rhizome, and a 1-year seedling on the right that germinated last summer; it does not have a developed rhizome yet.  I photographed these with the adult-size fans in view, to give an idea of size of these youngsters.

[cohan]

Interesting profile, I'll be watching for any of these that might be hardy enough; I like species Iris, and anything with 'woodland' in the description is a good starting point for me.. I don't mind the 'turf' effects, and plenty of space to let them do their thing...

[Hoy]

Very interesting, Mark!
I have for years thought to start growing some of these irises. No you have persuaded me to make an attempt this summer - if I can lay may hands of some nice plants! Too long to wait for seedlings to grow.

[AmyO]

Thanks for this Mark. Very informative and it gives me inspiration & confidence to get out & collect seed from my Iris cristata 'Powder Blue Giant' and 'Alba' this spring! I purchased an I. odeasanensis from Jan & Marty last year at the EWWSW and I'm looking froward to seeing its bloom!

[WimB]

VERY nice, Mark.

You're going to get me hooked on a new plant-addiction (and I already have to many  ). I wonder where I can find these in Europe...

I like Iris cristata 'Sam's Mini', Iris minutoaurea and Iris species novum the most.

[Todd Boland]

For some reason I have no luck with Iris cristata 

[Lori S.]

I've never managed to winter I. cristata over here either, maybe for different reasons - who knows?  Do other Calgarians out there grow it successfully?

[McDonough]

Hmm, I have never given it a second thought, about Iris cristata hardiness.  They never show the slightest indication of winter kill, so I just assumed if they perform this well in USDA Zone 5, they might do nearly as well in Zone 4.  Checking the USDA Plant Profile for Iris cristata, I see that it is definitely a Eastern USA species centered in central to southern States, with a disjunct distribution to include little ol' Massachusetts (in USDA, Massachusetts not included in FNA).  So it surprises me to learn it is not growable in Alberta nor Newfoundland!
http://plants.usda.gov/java/profile?symbol=IRCR