On 2 Feb 2013, at 13:03, Karl Church wrote: > Hi folks, I'm new to PBS & recently started attending Master Gardener > classes. Last meeting a classmate stated that all of her Irises had changed > from multi-colored to all yellow. She had pictures of her yard showing many > different colors & then again with them all changed to yellow & she wanted to > know if anyone knew the cause for the change. Anybody out there have an > answer for her? What kind of irises? Bearded? Spurias? Pacific Coast? Reticulata? Oncocyclus? Reglia? Limniris? At a guess, she is referring to "Dutch irises", bulbous ones that are very complex hybrids, which you can buy as mixed colors. I've even bought them at Safeway in boxes (in the fond hope, not realized, that they'd be Spanish irises). Mine, originally a mix of blue, white, and yellow, are now all blue. This happens because different cultivars respond differently to local conditions: some thrive, some die out. QED. So her irises haven't changed. It's just that only the yellow ones have survived, but they've increased. In my case, I suspect it's that they were planted where they are waterlogged in the winter, a situation that puts many bulbous plants to the test. The same thing happens with some other plants, too. One color is, for reasons unknown, hardier than the others and survives where others die out. I think there's a yellow dahlia that's notably hardier than most and takes over dahlia plantings left to their own devices over winter. -- Rodger Whitlock Victoria, British Columbia, Canada Z. 7-8, cool Mediterranean climate