No purple leaves for me so far. But the weather has been consistently cloudy and cool. If, it were to clear off and the lilies were all of a sudden exposed to very bright, intense sun--then I think I would have a good chance that I would see it on plants here and there (like one or two in a group of six). I think those most susceptable are the ones with a weakened bulb (for whatever reason) going into the spring growing season. That's what I found and concluded last year. I don't think temperatures have to be really hot either--just a too rapid of a change to several days of extremely bright, intense sunlight that follows an extended cloudy, cool period would do it. Of couse, adding heat could agrevate the situation, but that's not the case this year.
I also believe that rapid upward growth caused by an early warm spell depletes most of a weakened bulbs energy, before the stem has had adequate time to establish enough stem roots for continued uniform growth support throughout. Of course, last years weather was pretty unique, but the ones I examined last year had smaller, softer, nearly depleted bulbs with small, not fully developed stem roots. Those I repotted did not survive, but their stem bublets did. Orientals, or hybrids of them, seemed most affected. I did not see any with my Trumpets and Aurelians.
I don't think it's a soil/nutritional condition either because it only happens to one here and there. Anyway, it's too late to add the eggshells, oyster shells by the time one sees the condition for any type of immediate cure. There is none at that point, except just let the plant grow though it and hope for next year.
I'm am really curious to know exactly what biological process it is that is so disrupted that it causes a chemical change (or lack of it) inside the leaf itself, so as to form the purple color. What process can it be, that is not being completed?
Moby, your propping up that little limp lily is interesting. I had one exactly like that last year; I did the same thing as you did. It lived all summer long, short and stunted, but this year is just fine. While yours continued to grow nicely at least for a while, that ordeal may have something to do with its purple leaf condition now.
