As I have mentioned in at least a couple of threads, I am having a disappointing amount of bloom this season. This, in spite of throwing around quite a lot of 5-10-5 (and a little superphosphate) starting back in mid February.

Now, my garden has a fair amount of shade, and I am sure that over the years the amount of shade has grown. I have to question whether the scarcity of iris bloom is a function of perhaps not fertilizing enough (maybe I should be fertilizing in the fall, too?) or of not enough sun.

If my problem is the latter, then maybe I should be looking at growing shade tolerant irises (instead of the large number of bearded irises that I just ordered ).

Coincidental to buying some other plants, I recently purchased 2 Iris x 'Nada' from Greenwood Garden, because this plant is supposedly suited to dry shade.



The Pacific Coast Iris seedlings at the show yesterday were so beautiful, that I did a search on them. (In my area I think they can do with some shade. I used to have some PCIs (the landscaper put them in so I don't know if any of these were named cultivars). Most of them had ugly colors and didn't tolerate shade well, but one was somewhat pretty and bloomed in part shade. I am now regretting getting rid of it.)

In my search, up popped Annie's Annuals, with a listing. While their PCIs weren't currently available, their Iris confusa plants were.

Now, those confusa look interesting, but it is unclear how rapidly they spread. I am considering taking a chance on 'Chengdu', but I was wondering if anyone had experience with this genus of irises - is this plant going to take over my garden?



And since I am looking at shade irises, does anyone have any recommendations for any other kinds of irises that will tolerate shade? Or, for that matter, for bearded iris cultivars that will tolerate shade?

All my iris are in full sun. I don't have any experience of growing them in shade. Sorry

Most irises like at least a half day sun. The crested irises I. cristata can grow in partial shade. See Joe Pye Weed irises. jpwflowers.com Most are collected but David Schmeider is starting to hybridize them.

Thanks for that link, Lucy. I'm thinking of getting a few of the crested irises, and maybe also a few other plants. I think 'Mountain Girl' is calling my name.

I think I remember 'Chengdu' being similar to I. japonica, which spreads, but not voraciously. Although, I have to say, there are many, many plants that I've been sucked into by Annies that are weedy pests.

Hmm... I've been considering where I could place 'Chengdu', where it would not be too much of a pain to try to control it, if it tries to escape. There's a large mostly bare area under a beech and oak that might be suitable; the closest plants nearby would be the Erica that I planted earlier this year, and various other plants leading down to the creek. It would be bounded on two sides by a wooden deck (with a long stone step), and the creek.

I grow some Irises in shade and have no problem with them blooming. Are you sure that it isn't another issue? Perhaps the rhizomes are too crowded?

Both issues can work that way. When they look invasive, time to divide anyway. Just like normal beardeds do just when you have a large clump. ☺

So you are telling me, if I have a large clump of irises, I need to divide them and spread them out, if I want to see bloom?

That could partly explain some of what I am seeing, however I have two crowded clumps of 'Sweet Musette' and both put on a good show last year. I'll have to wait and see how much bloom I get this year (admittedly, I am seeing very few scapes coming up).

(Yeah, I'm a lazy gardener. I don't even divide the daylilies unless driven to it. I have one that I really love that I think clearly needs dividing, but it is up in a tall planter box, and it is going to be a real pain to get that out. This close to bloom season, I'm not sure that I want to try.)

Since I have your attention wrt scarcity of bloom, I have to ask about fertilizers. In previous years I liquid fertilized the irises with a 16-16-16 (or maybe it was 3-20-20?) Maxsea fertilizer. (I may also have previously scratched in an all-purpose fertilizer, Osmcote, which I think is 15-9-12, on the potted irises.) This year I fertilized with granular 5-10-5, and a bit of superphosphate on a couple of clumps, since that is what I discovered I should be using... or am I wrong? Because right now bloom is looking no better than last year, and for some irises, even worse. (Those irises I think are definitely now getting too much shade; when I looked last week, I did not see a single stalk coming up.)

you may be using to much fertilizer, if they are over fertilized they will not bloom also.

I use about two tablespoons of 5-27-5, scattered around the edges of a 18"-20" clump....less on smaller plants......twice , during the season. 1st time, as soon as I see new growth, and the 2nd, about 2-3 weeks after bloom has finished. This would apply to the 'oncers", the rebloomers get a different timetable. The best thing , is to have your soil tested (or, get a kit, and do it yourself) so you know that your ph is correct, and, just how much (if any) fertilizer you might need to add. It's better to have them "hungry", than to overfeed them !
Different cultivars, of course, can grow at different rates, but, as a rule.....every 3-4 years, they should be lifted, and divided....this is also a good time to 're new" the soil with compost, or other needed amendments.
As to sun / shade requirements for bearded, again, there are some cultivars that do slightly better than others, but, a half day of sun will get you some bloom, with all of the bearded. More sun= more bloom

What....irises can be overfed.....?

The only spot in my garden which comes close to "full sun" is my Moon Garden. All of the bearded irises in (or going in) there are white, though along the edges I also have a couple of pinks. There are some other areas in the Near 40 which get just a little more shade and a bit less sun; one of those already has 'Luminosity' in it, and I will add in a few more this summer. I will have to see about shoehorning an iris or few into the other areas. Anywhere else in the garden (where there is planting space), the irises will get a few hours of sun, if that.

Thanks to Lucy's link , I just mailed off an order to Joe Pye Weed's Garden, mostly for some Iris cristata plants for my shady areas. I also included one Siberian iris to try out (I have some "mystery" iris plants which the landscaper put in, but I don't know what they are... Siberian? Spuria? maybe this will help me tell? ), one drought tolerant species iris, and some primroses.

On the list:

I. cristata 'Edgar Anderson', Mountain Girl', 'Navy Blue Gem', 'Powder Blue Giant'
I. lactea 'Tough Cookie'
I. siberica 'Dance Party'
Primula sieboldii 'Ice Princess', 'Late Snow', 'Smooch', 'Starlight'





And oh yes, I am pulling the trigger on the I. confusa 'Chengdu'; it looks too pretty not to try.

Here's hoping the gophers don't get any of these (and that the rabbits don't like primroses, and that we've finally managed to keep the deer OUT).

Nice order there, I really like Tough Cookie and I now I recall being interested in their primroses- thanks for the reminder!

When I first moved here there were bearded irises crowded all along the side of the house, shaded by a spruce tree and a sycamore. The spruce had to go, it shaded the whole side of the house and cut off visibility from the windows. The area was then in partial shade of a deciduous tree that became pretty dense shade by mid summer and the irises started blooming. Then I started thinning them out and other colors started showing up the next year. The most plentiful noid of them blooms profusely in spite of the shade, which is why I have left a bunch there.

I believe some varieties are more tolerant of shade than others, unfortunately there doesn't seem to be much info available on shade tolerance of specific varieties.

Ooohh...perhaps this is a quality you can breed for?

I just came back from the nursery.. actually a couple of them.. There are a lot of PCI's in bloom right now to choose from.

Siberians like acid soil. Use Mir-acid as a fertilizer. Keep the first # low on irises (nitrogen) as a high number can go to leaves. 16 is way too much. We use 5-10-10.

Neal, be aware that per their (online) catalog, this is the last year that Joe Pye Weed's Garden is selling primroses.

Lucy, thanks for the "acid soil" tip.

Sherry, there were some absolutely gorgeous PCI seedlings at our iris show. It is making me rethink them... except, of course, I want those seedlings!

All of my Pacific Coast irises are growing in the shade. They don't grow as well here in the sun. Chengdu is also in the shade. It turns into such a monster clump, incidentally, that I had to give most of mine to Calif_Sue.

I used to have some at one time, but I only liked the flower on one of them. Eventually I got tired of it, and gave it away. With the dearth of TB iris bloom this season, and having seen such gorgeous PCI seedlings, I am rethinking that.

Thank you for the warning on 'Chengdu'. It will have some room to spread out, and I'll keep an eye on it.

I am wondering how much shade is too much. Guess I will just have to make a few trial plantings in various spots and see how they do.

te="Muddymitts"]I grow some Irises in shade and have no problem with them blooming. Are you sure that it isn't another issue? Perhaps the rhizomes are too crowded?[/quote]

One that I have grown for close to 25 years and tolerates a fair amount of shade is Crystal Glow. I bought it because it is a late bloomer and I wanted to extend the iris season. It does bloom late and as my pine trees started to shade the garden more and more, this is one that continued to bloom whereas the others gave up blooming. It has bloomed every year even with the shade in the garden. It isn't the fanciest of blooms, but it has performed well under difficult conditions.
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