I bought this plant several years ago, largely on the basis of it supposedly being a polymerous daylily which was actually a tetraploid, such things being rare (at least at that time).
As with many "polymerous" daylilies, 'Osterized' proved to be something of a disappointment in that regard, at least in my garden. Over many years of observing it, I would say that it had polymerous blooms here maybe 1-2% of the time, at best. I got my plant from Judi Davisson, so it should have been the correct plant. I compared notes with Bill Maryott, who at the time was growing it in his fields (which get a lot more sun than my garden gets), and he said that he never noticed any polymerous blooms on his. (I bought one of his plants to verify this for myself.)
So as a polymerous daylily, 'Osterized' proved to be a bust - at least in my garden. (I suspect that there may be environmental factors at play wrt polymerous daylilies; I do not doubt that it performs better, as a poly, in other climates in other parts of the country.)
All of that said, 'Osterized' is still in my garden, despite not being polymerous, and not being a rebloomer.
I love the plant - not just the large fragrant blooms which always open well, but also the lovely deep green arching foliage. The foliage looks good from winter until late summer, when it starts dying back. I have never seen leaf streak on it. I only saw a tiny bit of rust on it, for the very first time ever, last year (when a great many other daylilies here had a great deal of rust on them (no, I do not spray for rust)).
The large blooms, as I said, always open well here, despite our cool evenings, and the scapes are strong enough to hold the blooms well above the foliage (but not absurdly or inappropriately so) without needing staking. I am generally not out in the garden until mid-morning, but I do have notes from last year that blooms on 'Osterized' were almost fully open at 6:47 am, after a particularly cool evening. Does this make it an EMO or a CMO? I don't know, but if I had to guess, I would say "yes". The blooms do seem to start opening the evening before. (I doubt that it is a nocturnal daylily; if so, it must have super-extended bloom, because the day's blooms are still in good shape come early evening, unlike certain registered nocturnal daylilies that I have had.)
The blooms are a lovely lemon yellow, and iirc they are lightly diamond dusted. I like yellow daylilies, and I like lemon yellow daylilies most of all - they are very cheerful, and fit well into the general garden. (I don't do monoculture.) I am a sucker for diamond dusting, so that (imho) is another plus.
The clump is reliably in bloom here from the last week of May, into the first week of July, giving me over a month of bloom. Once bloom begins, the clump is generally in bloom every day, except for the first few and last few days.
All of these traits: great foliage, large fragrant lemon flowers which open reliably and well (and early enough for me), held above the foliage on sturdy-enough scapes, make this a very good (if not great) daylily - good enough that I don't care that it doesn't rebloom, and that it rarely produces polys. It is, imho, highly deserving of its H.M. award. I look forward to its start of bloom every year, and I mourn when it comes to the last flower open. It certainly makes my "top 10" daylilies list, of those that (one way or another) I would scheme to take with me to a new house, or a desert island.
I would recommend this daylily to anyone.
Late edit (because I kept getting interrupted when I wrote the original post)... I forgot to mention hybridizing. 'Osterized' is pollen fertile but pod difficult, perhaps because of the long pistil. I *have* been able to set pods on it, with many tries. Bees seem to have no difficulty setting pods on it, though. Perhaps the trick is to get out there very early in the morning?
